JP3327907B2 - Receiving device and receiving method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a transmission apparatus for transmitting a digital signal by modulating a carrier wave.

[0002]

2. Description of the Related Art In recent years, digital transmission devices have been increasingly used in various fields. In particular, the development of digital video transmission technology is remarkable.

[0003] Among them, a digital TV transmission system has recently attracted attention. At present, digital TV transmission devices are only partially used for relaying between broadcasting stations. However, development to terrestrial broadcasting and satellite broadcasting is scheduled in the near future, and studies are being conducted in various countries.

[0004] In order to respond to the demands of increasingly sophisticated consumers, H
It is necessary to improve the quality and quantity of contents of broadcasting services such as DTV broadcasting, PCM music broadcasting, information providing broadcasting and FAX broadcasting in the future. In this case, it is necessary to increase the amount of information in a limited frequency band of TV broadcasting. The amount of information that can be transmitted in this band increases according to the technological limitations of the era. For this reason, it is ideally desirable to change the receiving system according to the times and expand the information transmission amount.

[0005] However, from the viewpoint of broadcasting, publicity is important, and it is important to secure vested rights of all viewers for a long period of time. When starting a new broadcasting service, it is a necessary condition that the existing receiver or receiver can enjoy the service. It can be said that the compatibility of the receiver or the receiver and the compatibility of the broadcasting between the past and present, and the present and future new and old broadcasting services are the most important.

[0006] New transmission standards that will appear in the future, such as the digital TV broadcasting standard, require expandability of the amount of information to meet future social requirements and technological advances, and compatibility and compatibility with existing receiving equipment. Have been.

[0007] Here, transmission systems of TV broadcasting that have been proposed so far will be described from the viewpoint of expandability and compatibility.

First, as a satellite broadcasting system of digital TV, N
A method has been proposed in which a signal obtained by compressing a TSC-TV signal to about 6 Mbps is multiplexed by a TDM method using 4-level PSK modulation and a single transponder broadcasts a TV program of 4 to 20 channels NTSC or one channel of HDTV. As a terrestrial broadcasting method of HDTV, a method of compressing a 1-channel HDTV video signal into data of about 15 Mbps and performing terrestrial broadcasting using a 16 or 32 QAM modulation method is being studied.

First, in the satellite broadcasting system, the currently proposed broadcasting system uses the NTSC frequency band of several channels for one-channel HDTV program broadcasting in order to simply broadcast by the conventional transmission system. For this reason, HDT
There is a problem that the NTSC program of several channels cannot be received and broadcast in the broadcast time zone of the V program. NTSC and H
It can be said that there was no compatibility or compatibility between the receiver and the receiver with the DTV broadcast. It can also be said that the scalability of the amount of information transmission required with future technological advances was not considered at all.

Next, the conventional HDT which is currently under study
V terrestrial broadcasting system uses HDTV signals of 16QAM or 32Q
It merely broadcasts in a conventional modulation scheme such as AM. In the case of the existing analog broadcasting, there is always an area having a bad reception state such as a building shadow, a lowland, or interference from an adjacent TV station even in the broadcasting service area.
In such an area, although the image quality deteriorates in the case of the existing analog broadcasting, the video can be reproduced and the TV program can be viewed. However, the conventional digital TV broadcasting system has a serious problem that no video can be reproduced at all in such an area and that no TV program can be viewed. This involves an essential problem of digital TV broadcasting, and was a problem that could be fatal to the spread of digital TV broadcasting. This is because the signal points of the conventional modulation method such as QAM or the like are arranged at equal positions or at equal intervals. Conventionally, there has been no method of changing or modulating the arrangement of signal points.

[0011]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems, and in particular, NTSC in satellite broadcasting.
It is an object of the present invention to provide a transmission apparatus which greatly reduces the compatibility between broadcasting and HDTV broadcasting, and greatly reduces unreceivable areas in a service area for terrestrial broadcasting.

[0012]

In order to achieve the above object, a transmission apparatus according to the present invention modulates a signal input section and a plurality of carriers having different phases by an input signal from the input section to obtain a signal vector diagram. A transmitter for transmitting data, comprising a modulator for generating an m-valued signal point and a transmitter for transmitting the modulated signal, an input unit for the transmission signal, and a QAM modulated wave of an l-valued signal point on a vector diagram And a receiving device having an output unit.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to this configuration, a first data sequence and a second data sequence having n-valued data are input as input signals, and a modulator having a m-valued signal point on a vector diagram by a modulator of a transmitting apparatus. A m-value QAM modulated wave is created. The m signal points are divided into n signal point groups, and the signal point groups are allocated to n data in the first data string, and m / n signal points or A transmission signal is transmitted by the transmitting device by allocating each data of the second data sequence to the sub-signal point group. In some cases, third data can also be transmitted.

Next, in a receiving apparatus having a demodulator having a p-value of p> m, the above-mentioned transmission signal is received, and p signal points are first set to n points on the signal space diagram. , And demodulate and reproduce the signal of the first data string. Next, p / n signal points in the corresponding signal point group are associated with the second data sequence of p / n values and demodulated to demodulate and reproduce the first data and the second data. In a receiver with p = n, n groups of signal points are reproduced, and only the first data string is demodulated and reproduced with each having an n value.

When the same signal is received from the transmitting device by the above operation, the first data sequence and the second data sequence can be demodulated by the large antenna and the receiver having multi-level demodulation capability.
At the same time, a small antenna and a receiver having a small demodulation capability can receive the first data string. Thus, a compatible transmission system can be constructed. In this case, the first data string is a low-frequency TV such as a low-frequency component of NTSC or HDTV.
In the signal, a second data string is added to a high frequency T such as a high frequency component of an HDTV.
By allocating to the V signal, a receiver having a small demodulation capability with respect to the same radio wave can receive an NTSC signal, and a receiver having a multi-level demodulation capability can receive an HDTV signal. This enables digital broadcasting compatible with NTSC and HDTV.

[0016]

(Embodiment 1) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an overall system diagram of a transmission apparatus according to the present invention. A transmitter 1 having an input section 2, a separating circuit section 3, a modulator 4 and a transmitting section 5 separates a plurality of multiplexed input signals into first data strings D ₁ and second data strings D
₂ and a third data string, D _3, are output by the modulator 4 as a modulated signal from the transmitter 5, and the modulated signal is transmitted to the artificial satellite 10 by the antenna 6 through the transmission line 7.
This signal is received by the antenna 11 in the artificial satellite 10, amplified by the repeater 12, and transmitted to the earth again by the antenna 13.

The transmission radio waves are transmitted to the first receiver 23, the second receiver 33, and the third receiver 43 through the transmission paths 21, 31, and 41.
Sent to First, in the first receiver 23, input is made from the input unit 24 via the antenna 22, only the first data sequence is demodulated by the demodulator 25, and output from the output unit 26. In this case, the second data string and the third data string have no demodulation ability.

In the second receiver 33, the signal output from the input unit 34 via the antenna 32 is converted by the demodulator 35 into the first signal.
The data sequence and the second data sequence are demodulated, combined by the combiner 37 into one data sequence, and output from the output unit 36.

In the third receiver 43, an input from the antenna 42 enters an input section 44 and a demodulator 45 outputs a first data string,
The three data strings of the second data string and the third data string are demodulated and combined into one data group by the combiner 47 and output from the output unit 46.

As described above, even when radio waves of the same frequency band are received from the same transmitter 1, the amount of receivable information differs due to the difference in the performance of the demodulators of the above three receivers. With this feature, it is possible to simultaneously transmit compatible three pieces of information according to the performance to receivers having different performances in one radio band. For example, NTSC and HD of the same program
When transmitting three digital TV signals of a TV and a super-resolution HDTV, a super HDTV signal is separated into a low-frequency component, a high-frequency difference component, and a super-high-frequency difference component, each of which is a first data stream,
Corresponding to the second data string and the third data group, three types of compatible digital TV signals of medium resolution, high resolution, and ultra high resolution can be simultaneously broadcast in the frequency band of one channel.

In this case, an NTSC-TV signal can be demodulated by a receiver for small-value demodulation using a small antenna, an HDTV signal can be demodulated by a receiver capable of medium-value demodulation using a medium-sized antenna, and multi-level demodulation using a large antenna can be used. Such a receiver can receive an ultra-high resolution HDTV. To further explain FIG.
A digital transmitter 51 for performing TSC digital TV broadcasting receives only the same data as the first data group from an input unit 52, modulates the data with a modulator 54, and transmits the data to a transmitter 55 and an antenna 5
6, the signal is transmitted to the satellite 10 via the transmission path 57 and transmitted again to the earth via the transmission path 58.

In the first receiver 23, the demodulator 24 demodulates the received signal from the digital transmitter 1 into data corresponding to the first data sequence. Similarly, the second receiver 33 and the third receiver 43 demodulate a data group having the same content as the first data string. In other words, the three receivers are digital general TV
Digital broadcasting such as broadcasting can also be received.

Next, each part will be described. FIG. 2 shows the transmitter 1
It is a block diagram of.

The input signal enters the input section 2 and is separated by a separation circuit 3 into three digital signals of a first data string signal, a second data string signal, and a third data string signal.

For example, when a video signal is input, the low frequency component of the video signal is a first data sequence signal, the high frequency component of the video signal is a second data sequence signal, and the super high frequency component of the video signal is a third data sequence. Assigning to signals is conceivable. 3 isolated
The two signals are input to a modulation input unit 61 inside the modulator 4. Here, there is a signal point position modulation / change circuit 67 that modulates or changes the position of a signal point based on an external signal, and modulates or changes the position of the signal point according to the external signal.
In the modulator 4, amplitude modulation is performed on each of two orthogonal carrier waves to obtain a multilevel QAM signal. The signal from the modulation input unit 61 is sent to the first AM modulator 62 and the second AM modulator 63. one of the carrier from the carrier generator 64 of cos (2πf _c t) are AM modulated by the 1AM modulator 62 is sent to the combiner 65, another carrier sent to the [pi / 2 phase shifter 66 It is 90 ° are phase-shifted, is fed to the 2AM modulator 63 in the form of sin (2πf _c t), after being amplitude-modulated in the multi-level, in the combiner 65 is combined with the first 2AM modulated wave, transmission The signal is output by the unit 5 as a transmission signal. Since this method has been generally implemented conventionally, a detailed description of the operation will be omitted.

The operation will be described with reference to the first quadrant of the signal space diagram of a general 16-value QAM shown in FIG. All signals generated by the modulator 4 have two orthogonal carriers.
Vector of Acos2πf _c t vectors 81 and Bsin2πf _c t 82
Can be represented by a composite vector of the two vectors. If the tip of the combined vector from the zero point is defined as a signal point, in the case of 16-value QAM, the four amplitude values of a ₁ , a ₂ , a ₃ , a ₄ and b ₁ ,
A total of 16 signal points can be set by combining four amplitude values of b ₂ , b ₃ , and b ₄ . In the first quadrant of FIG. 3, C _{11 of} the signal point 83, C _{12 of the} signal point 84, C _{22 of the} signal point 85,
Four signals C ₂₁ signal points 86 are present.

[0028] C ₁₁ is a composite vector of a vector 0-a ₁ and a vector _{0-b 1, C 11 =} a 1 cos2πf c t-b 1 sin2πf
to become _{c t = Acos (2πf c t} + dπ / 2).

Here, 0-a ₁ on the rectangular coordinates in FIG.
A ₁ the distance between, a ₁ -a ₂ between the A _2, 0-b ₁ between the B _1, b
Between ₁ -b ₂ is defined as B _2, shown on the diagram.

As shown in the overall vector diagram of FIG. 4, there are a total of 16 signal points. Therefore, by associating each point with 4-bit information, 4-bit information transmission becomes 1
This is possible during a period, that is, one time slot.

FIG. 5 shows an example of a general assignment when each point is expressed in a binary system. Of course, the greater the distance between each signal point, the easier it is for the receiver to distinguish. Therefore, in general, the arrangement is such that the distance between the signal points is as far as possible. If the distance between specific signal points is reduced,
In the receiver, it becomes difficult to distinguish between the two points, and the error rate deteriorates. Therefore, it is generally said that it is desirable to arrange them at equal intervals as shown in FIG. Therefore 16QA
In the case of M, the arrangement of signal points where A1 = A2 / 2 is generally implemented.

Now, in the case of the transmitter 1 of the present invention, first, data is divided into a first data string and a second data string, and possibly into a third data string. Then, as shown in FIG. 6, the 16 signal points or signal point groups are divided into four signal point groups, and the four data of the first data string are first allocated to each signal point group. That is, when the first data string is 11, one of the four signal points of the first signal point group 91 in the first data quadrant is transmitted, and when the first data string is 01, the second signal point group 92 in the second quadrant is transmitted. , 00, the third signal point group 93, 10 in the third quadrant
In this case, one signal point is selected from the four signal points in the fourth signal point group 94 in the fourth quadrant according to the value of the second data string and transmitted. Next, in the case of 16 QAM, 2 bits of the second data string, 4-value data, and in the case of 64-value QAM, 4 bits
It, 16-level data is allocated to four signal points or sub-signal point groups in each of the divided signal point groups 91, 92, 93, and 94 as shown in FIG. All quadrants are targeted. Assignment of signal points to 91, 92, 93, and 94 is preferentially determined by 2-bit data of the first data group. Thus, 2 bits of the first data string and 2 bits of the second data string
Can be transmitted completely independently. The first data string can be demodulated even by a 4PSK receiver if the antenna sensitivity of the receiver is equal to or more than a certain value. If the antenna has higher sensitivity, both the first data group and the second data group can be demodulated by the modified 16QAM receiver of the present invention.

FIG. 8 shows an example of allocation of two bits of the first data string and two bits of the second data string.

In this case, the HDTV signal is divided into a low-frequency component and a high-frequency component, a low-frequency video signal is allocated to the first data sequence, and a high-frequency video signal is allocated to the second data sequence.
In the PSK receiving system, the NTSC equivalent video of the first data stream can be reproduced, and in the 16 QAM or 64 QAM receiving system, both the first data stream and the second data stream can be reproduced, and these are added to obtain an HDTV video. be able to.

However, when the distance between signal points is made equal as shown in FIG. 9, there is a threshold distance between the hatched portion in the first quadrant as viewed from the 4PSK receiver. If the threshold distance is A _TO and only 4PSK is sent, the amplitude of A _TO is sufficient. But which is the required amplitude of 3A _TO i.e. 3 times when you send 16QAM while maintaining A _TO.
That is, nine times as much energy is required as when transmitting 4PSK. Sending 4PSK signal points in 16QAM mode without any consideration is inefficient in power use. Regeneration of the carrier wave also becomes difficult. The power available for satellite transmission is limited. Such a system with poor power utilization efficiency is not practical until the transmission power of the satellite increases. 4PSK when digital TV broadcasting starts in the future
It is expected that a large number of receivers will be available. Once spread, it can be said that it is impossible to increase these receiving sensitivities because of the problem of receiver compatibility. Therefore,
The transmission power in the 4PSK mode cannot be reduced. Therefore 16
When transmitting a pseudo 4PSK signal point in the QAM mode, it is expected that a method of lowering the transmission power than the conventional 16QAM is required. Otherwise, transmission will not be possible with limited satellite power.

The features of the present invention are shown in FIG.
The point is that the transmission power of the quasi-4PSK type 16QAM modulation can be reduced by increasing the distance between the 94 divided signal point groups.

Here, in order to clarify the relationship between the receiving sensitivity and the transmission output, returning to FIG. 1, the receiving method of the digital transmitter 51 and the first receiver 23 will be described.

First, the digital transmitter 51 and the first receiver 2
A general transmission device 3 performs data transmission or video transmission including broadcasting. As shown in FIG. 7, the digital transmitter 51 is a 4PSK transmitter, which is obtained by removing the AM modulation function from the multilevel QAM transmitter 1 described in FIG. The input signal is input to the modulator 54 via the input unit 52. In the modulator 54, the modulation input unit 121 divides the input signal into two signals and performs first phase modulation on the reference carrier.
-2 phase modulation circuit 122 and a 2-2 phase modulation circuit 123 for modulating a carrier having a 90 ° phase difference from the reference carrier.
And these phase modulated waves are synthesized by a synthesizer 65,
Transmitted by the transmission unit 55.

FIG. 18 shows a modulated signal space diagram at this time. In general, it is common practice to set four signal points and make the distance between signal points equal to increase the power use efficiency. As an example, a case where signal point 125 is defined as (11), signal point 126 is defined as (01), signal point 127 is defined as (00), and signal point 128 is defined as (10). In this case, in order for the first receiver 23 of 4PSK to receive satisfactory data, the output of the digital transmitter 51 is required to have a certain amplitude value or more. Referring to FIG. 18, the first receiver 23 needs the minimum amplitude value of the transmission signal, ie, 0-a _{1, which} is the minimum necessary for receiving the signal of the digital transmitter 51 at 4PSK.
If the distance between them is defined as A _TO , the first receiver 23 can receive if the signal is transmitted at the minimum amplitude A _{TO of the} transmission limit or more.

Next, the first receiver 23 will be described. First
The receiver 23 receives the transmission signal from the transmitter 1 or the 4PSK transmission signal from the digital transmitter 51 via the repeater 12 of the satellite 10 with the small antenna 22, and the demodulator 24 converts the reception signal into a 4PSK signal. And demodulate. The first receiver 23 is originally a 4P of the digital transmitter 51.
It is designed to receive SK or 2PSK signals and to receive signals such as digital TV broadcasting and data transmission.

FIG. 19 is a block diagram showing the structure of the first receiver. The radio wave from the satellite 12 is received by the antenna 22. After this signal is input from the input unit 24, the carrier recovery circuit 131 and the π / 2 phase shifter 132 A carrier wave and a quadrature carrier wave are reproduced by the first phase detection circuit 133 and the second phase detection circuit 1 respectively.
34, the orthogonal components are detected independently of each other. The timing wave extracting circuit 135 independently detects each component for each time slot. The first and second discriminating circuits 136 and 137 detect two independent components. The demodulated signal is demodulated into a first data string by a first data string reproducing unit 232, and output by an output unit 26.

Here, the received signal will be described with reference to the vector diagram of FIG. The signal received by the first receiver 23 on the basis of the 4PSK transmission radio wave of the digital transmitter 51 is a signal shown in FIG.
It can be represented by four signal points 1 to 154.

However, actually, the received signal points are distributed in a certain range around the signal point under the influence of noise in the transmission path and amplitude distortion and phase distortion of the transmission system. The error rate gradually increases because the signal point cannot be distinguished from the adjacent signal point when the signal point is apart from the signal point. When the signal point exceeds a certain set range, data cannot be restored. In order to perform demodulation within the set error rate even in the worst condition, the distance between adjacent signal points may be set. This distance is defined as 2A _RO . At the time of the limit reception input of 4PSK, the signal point 151 is | 0−a _R1 | ≧ in FIG.
A _R0 , | 0−b _R1 | ≧ A _R0 , the first discrimination region 1 indicated by oblique lines
If the transmission system is set to be within 55, demodulation can be performed if the carrier can be reproduced. Assuming that the minimum radius value set by the antenna 22 is r ₀ , all systems can receive the signal if the transmission output is set to a certain value or more. The amplitude of the transmission signal in FIG. 18 is set to be the 4PSK minimum reception amplitude value of the first receiver 23, A _R0 . This transmission minimum amplitude value is defined as A _T0 . Thus, if the radius of the antenna 22 is equal to or greater than r _0, the first receiver 23 can demodulate the signal of the digital transmitter 51 even if the reception condition is the worst. When receiving the modified 16QAM and 64QAM of the present invention, it becomes difficult for the first receiver 23 to recover the carrier. Therefore, as shown in FIG. 25 (a), the transmitter 1 is set to (π / 4 + nπ /
If eight signal points are arranged and transmitted at the position on the angle of 2), the carrier can be reproduced by the quadrupling method. FIG.
If 16 signal points are arranged on the extension line of the angle of nπ / 8 as shown in FIG. 2B, the signal points are degenerated by employing the 16-times carrier recovery method in the carrier recovery circuit 131, and the pseudo 4PSK type 16QAM is used. The carrier of the modulated signal can be easily reproduced. In this case, A ₁ / (A ₁ + A ₂ ) = tan (π /
The signal point of the transmitter 1 may be set and transmitted so as to satisfy 8). Here, consider the case of receiving a QPSK signal. As in the signal point position modulation / change circuit 67 of the transmitter in FIG. 2, the signal point position (FIG. 18) can be superimposed with the modulation such as AM on the signal point position of the QPSK signal. In this case, the signal point position demodulator 138 of the first receiver 23 demodulates the position modulation signal or the position change signal of the signal point to PM, AM, or the like. Then, a first data string and a demodulated signal are output from the transmission signal.

Next, returning to the transmitter 1, the transmission signal of 16PSK of the transmitter 1 will be described with reference to the vector diagram of FIG. 9, as shown in FIG.
₁ larger than 4PSK minimum transmission output A _TO of the digital transmitter 51 of FIG. 18. Then, the signals at the signal points 83, 84, 85 and 86 in the first quadrant of FIG.
It enters the SK receivable area 87. When these signals are received by the first receiver 23, these four signal points fall into the first discrimination area of the reception vector diagram of FIG. Therefore, the first receiver 23 determines that the signal point is the signal point 151 in FIG. 20 regardless of whether any of the signal points 83, 84, 85, and 86 in FIG. 9 is received, and (11)
Is demodulated in this time slot. This data is (11) of the first divided signal point group 91 of the transmitter 1, that is, (11) of the first data string, as shown in FIG. The first data string is similarly demodulated in the second, third, and fourth quadrants. That is, the first receiver 23 demodulates only the 2-bit data of the first data string among the plurality of data strings of the modulation signal from the 16 QAM, 32 QAM, or 64 QAM transmitter 1.
In this case, since the signals of the second data string and the third data string are all included in the first to fourth divided signal point groups 91, the signal of the first data string is not affected. However, it has an effect on the reproduction of the carrier wave, so that the following measures are required.

If there is no limit to the output of the satellite transponder, the conventional signal point equidistant system shown in FIG.
It can be realized by 64QAM. However, as described above, unlike terrestrial transmission, in satellite transmission, the launch cost increases significantly as the weight of the satellite increases. Therefore, the transmission output is restricted by the output limit of the repeater of the main body and the power limit of the solar cell. This situation will continue for some time unless the launch cost of the rocket is reduced by technological innovation. The transmission output is about 20 W for a communication satellite and about 100 W to 200 W for a broadcast satellite. Therefore, the 16QA signal point equidistant method shown in FIG.
When trying to transmit 4PSK at M, the amplitude of 16QAM is 2A ₁ = A ₂ , so 3A _{TO is} required, which is required 9 times in terms of power. 4PSK for compatibility
Requires nine times the power. Also, when trying to make the first receiver of 4PSK also receivable with a small antenna, at present,
It is difficult to obtain such output with the planned satellite. For example, a system of 40 W requires 360 W and cannot be realized economically.

Here, when all the receivers are considered to have the same size antenna, it is possible to obtain the same area signal efficiency with the same transmission power if the receivers have the same transmission power. However, a new transmission system can be configured by considering a system in which receiver groups of antennas having different sizes are combined.

More specifically, 4PSK increases the number of receivers by receiving a signal with a simple and low-cost receiving system using a small antenna. Next, 16QAM is a high-performance but high-cost multi-level demodulation receiving system that uses a medium-sized antenna, receives high-value-added services such as HDTV that matches the investment, and limits the target to specific recipients. To establish. In this way, 4PSK and 16QAM, and in some cases, 64DMA can be transmitted hierarchically by slightly increasing the transmission output.

For example, by setting the signal point interval so that A1 = A2 as shown in FIG. 10, the total transmission output can be reduced. Amplitude A (4) for transmitting this case 4PSK can be expressed by a vector 95, the 2A ₁ ² of the square root. The total amplitude A (16) can be represented by a vector 96 (A
₁ + A ₂ ) ² + (B ₁ + B ₂ ) ² .

[0049] ^{| A (4) | 2 =} A 1 2 + B 1 2 = A TO 2 + A TO 2 = 2A TO 2 | A (16) | 2 = (A 1 + A 2) 2 + (B 1 + B 2) ² = 4A
_TO ² +4 A _TO ² = 28 A _{T O} ² | A (16) | / | A (4) | = 2 That is, transmission can be performed with twice the amplitude and four times the transmission energy in the case of transmitting 4PSK. By can not demodulate variations 16 QAM is a common receiver for transmitting at equidistant signal points set in advance the two thresholds A ₁ and A ₂ second
It can be received by the receiver 33. For Figure 10, the shortest distance between the signal points in the first division signal point group 91 is A _1, 4PS
Compared to signal point distance 2A ₁ of K A ₂ / 2A ₁ becomes. A ₁
= From A ₂ becomes the distance between the half of the signal points, in order to obtain a same error rate twice the reception sensitivity of the amplitude, it is necessary to receive sensitivity of four times the energy. To obtain 4 times the receiver sensitivity, if the radius r ₂ of the antenna 32 of the second receiver 33 twice i.e. r ₂ = 2r ₁ as compared to the radius radius r ₁ of the antenna 22 of the first receiver 23 Good. For example, if the antenna of the first receiver 23 has a diameter of 30 cm, this can be realized by setting the antenna diameter of the second receiver 33 to 60 cm. As a result, by demodulating the second data string and allocating it to the high frequency component of HDTV, a new service such as HDTV can be performed on the same channel. Since the service content is doubled, the receiver can receive the service corresponding to the investment of the antenna and the receiver. Therefore, the cost of the second receiver 33 may be higher. Here, since the minimum transmission power is determined for the 4PSK mode reception, A in FIG.
Modification 1 for transmission power of 4PSK by ratio of ₁ and A ₂
The transmission power ratio n _{16 of} 6APSK and the antenna radius r ₂ of the second receiver 33 are determined.

When calculating to measure this optimization, 4
The minimum required transmission energy of PSK is {(A ₁ + A ₂ ) /
A ₁ } ² times If this is defined as n ₁₆ , the distance between signal points when receiving with modified 16-value QAM is A ₂ , the distance between signal points when receiving with 4 PSK is 2A ₁ , and the ratio of the distance between signal points Is A ₂ / 2A, so if the radius of the receiving antenna is r ₂ , the relationship is as shown in FIG. Curve 101 is the transmission energy magnification n ₁₆ and the radius r of the antenna 22 of the second receiver 23.
₂ represents the relationship.

Point 102 is 16QA for equidistant signal points
In the case of transmitting M, the transmission energy is required to be nine times as described above, which is not practical. From FIG. 11, it can be seen from the graph that the antenna radius r ₂ of the second receiver 23 does not become so small even if n ₁₆ is increased by 5 times or more.

In the case of a satellite, the transmission power is limited,
Cannot exceed a certain value. From this, it becomes clear that n16 is desirably 5 times or less. This area is shown by the hatched area 103 in FIG. For example, within this area, for example, the point 104 has transmission energy four times and the antenna radius r ₂ of the second receiver 23 doubles. At the point 105, the transmission energy is doubled, and r ₂ is approximately five times. These are in a range that can be put to practical use.

When the fact that n ₁₆ is smaller than 5 is expressed by A ₁ and A ₂ , n ₁₆ = ((A ₁ + A ₂ ) / A ₁ ) ² ≦ 5 A ₂ ≦ 1.23A ₁ FIG. the distance between 2A (4), when the maximum Fuhaba 2A (16), a (4 ) and a (16) -A (4) are a ₁ and a ₂
Therefore, it is sufficient to set {A (16)} ² ≦ 5 {A (14)} ^2. Next, an example using a modified 64APSK modulation will be described. The third receiver 43 can perform 64-level QAM demodulation.

The vector diagram of FIG. 12 shows a case where the divided signal point group of the vector diagram of FIG. 10 is increased from four values to 16 values. In the first divided signal point group 91 of FIG.
Signal points of 4 × 4 = 16 values starting from 0 are arranged at equal intervals. In this case, the transmission amplitude must be set to A ₁ ≧ A _TO in order to have compatibility with 4PSK.
Assuming that the radius of the antenna of the third receiver 43 is r ₃ ,
The value of r ₃ when defined as output signal n64, when determined in the same manner ^{_{r 3 2 = {6 2 /}} (n-1)} r 1 2 , and the radius r ₃ in FIG. 13 64 value QAM - Output multiple It becomes a graph like n.

However, in the arrangement as shown in FIG. 12, when the signal is received by the second receiver 33, only 2 bits of 4PSK can be demodulated, so that the first, second and third compatibility must be satisfied by the second reception. It is desirable that the device 33 have a function of demodulating the modified 16-level QAM from the modified 64-level QAM modulated wave.

As shown in FIG. 14, by grouping signal points of three layers, compatibility of the three receivers is established. Explaining only in the first quadrant, it has been stated that the first divided signal point group 91 is assigned 2-bit (11) of the first data string.

Next, the first sub-divided signal point group 181 has the second
2 bits (11) of the data string are allocated. (01) is assigned to the second sub-divided signal point group 182, (00) is assigned to the third sub-divided signal point group 183, and (10) is assigned to the fourth sub-divided signal point group 184. This is equivalent to FIG.

The signal point arrangement of the third data string will be described in detail with reference to the vector diagram of the first quadrant in FIG. 15. For example, signal points 201, 205, 209 and 213 are (11) and signal points 202, 206, 210, and 214 to (01), signal point 2
03, 207, 211 and 215 to (00), signal point 20
If 4,208,212,216 is (10), the third
The 2-bit data of the data string can be transmitted independently of the first data and the second data, and the 3-bit 2-bit data can be transmitted independently.

In addition to transmitting 6-bit data, the present invention is characterized by three levels of receivers having different performances.
It is possible to transmit data of different transmission amounts of bit, 4 bits, and 6 bits, and to achieve compatibility between the transmissions of the three layers.

Here, a method of arranging signal points necessary for achieving compatibility during three-layer transmission will be described.

As shown in FIG. 15, first, in order for the first receiver 23 to receive the data of the first data string, A ₁
It has already been mentioned that ≧ A _TO .

Next, the signal point of the second data string, for example, FIG.
The signal point 91 of FIG.
It is necessary to secure a distance between signal points so that the signal points can be distinguished from 3,184 signal points.

FIG. 15 shows a case where the distance is 2/3 A ₂ . In this case the signal between point distance of the internal signal points 201 and 202 of the first sub-division signal point group 181 becomes A _2/6. Third
The reception energy required for reception by the receiver 43 is calculated. In this case, assuming that the radius of the antenna 32 is r ₃ ,
Required transmission energy is 4PSK transmission energy n _{6 4}
When defined as a ^{_{multiplication, r 3 2 = (12r 1}} ) become This graph ² / (n-1) represented by the curve 221 in FIG. 16. For example, point 2
In the case of 22, 223, the first, second, and third data strings can be obtained by an antenna having an eight-fold radius if transmission energy six times as large as 4PSK transmission energy can be obtained, or by a six-fold antenna if transmission energy is nine times as large. It can be seen that demodulation can be performed. In this case, since the distance between the signal points of the second data string approaches 2 / 3A ₂ , r ₂ ² = (3r ₁ ) ² / (n−1), and the antenna 32 of the second receiver 33 slightly as shown by a curve 223.
Need to be larger.

In this method, the first data string and the second data string are transmitted while the transmission energy of the satellite is small as of the present time, and in the future when the transmission energy of the satellite is greatly increased, the first receiver 23 and the second data string are transmitted. The third data stream can be sent without damaging the data received by the second receiver 33 and without any modification, and thus a great effect of both compatibility and developability can be obtained.

In order to explain the receiving state, the second receiver 33 will be described first. The above-mentioned first receiver 23 originally has a radius r
The first data column of 4PSK modulation signal and the transmitter 1 of the digital transmitter 51 while is set so as to be demodulated by ₁ small antennas, as shown in FIG. 10 of the transmitter 1, the second receiver 33 16-value signal point, that is, 1 of the second data string
A 2-bit signal of 6QAM can be completely demodulated. A 4-bit signal can be demodulated together with the first data string. In this case, the ratio of A1 and A2 differs depending on the transmitter. This data is set by the demodulation control unit 231 in FIG. 21 and a threshold is sent to the demodulation circuit. This enables AM demodulation.

A block diagram of the second receiver 33 in FIG.
The block diagram of the first receiver 23 in FIG. 19 has almost the same configuration. The difference is that first, the antenna 32 has a larger radius r ₂ than the antenna 22. Therefore, a signal having a shorter signal point distance can be discriminated. Next, demodulator 3
5, a demodulation control unit 231 and a first data string reproducing unit 2
32 and a second data string reproducing unit 233. The first identification reproduction circuit 136 has an AM demodulation function for demodulating the modified 16QAM. In this case, each carrier has a quaternary value, and has a zero level and ± a binary threshold. In the case of the present invention,
Because of the modified 16QAM signal, the threshold value differs depending on the transmission output of the transmitter as shown in the signal vector diagram of FIG. Therefore,
When thread hold values were normalized to TH _16, FIG. 22
As apparent from the _{TH 16 = (A 1 + A} 2/2) / (A 1 + A 2).

[0067] demodulation information of the A1, A2 or TH _16, and the multilevel modulation values m, from the transmitter 1, is transmitted included in the first data stream. In addition, there is a method in which the demodulation control unit 231 statistically processes the received signal to obtain demodulation information.

Referring to FIG. 26, shift factor A ₁ / A ₂
A method of determining the ratio of the above will be described. Changing A ₁ / A ₂ changes the threshold. Error accordance A ₁ / A ₂ set at the receiver side moves away from the value of A ₁ / A ₂ set at the transmitter side will increase. The demodulated signal from the second data stream reproducing unit 233 shown in FIG. 26 is fed back to the demodulation control circuit 231 to control the shift factor A ₁ / A ₂ in the direction of decreasing the error rate, so that the third receiver 43 can shift the shift factor. A
_Since it is not necessary to demodulate ₁ / A ₂ , the circuit is simplified. In addition, the transmitter does not need to send A ₁ / A _2, which has the effect of increasing the transmission capacity. This can be used for the second receiver 33. The demodulation control circuit 231 includes a memory 231a
have. When a threshold value different for each TV broadcast channel, that is, a shift ratio, the number of signal points, and a synchronization rule is stored and the channel is received again, recalling this value has an effect that reception is fast and stable.

If the demodulation information is unknown, demodulation of the second data string becomes difficult. This will be described below with reference to the flowchart of FIG.

Step 3 even if demodulation information cannot be obtained
Thirteen demodulation of 4PSK and the demodulation of the first data string in step 301 can be performed. Therefore, in step 302, the demodulation information obtained by the first data string reproducing unit 232 is
Send to 1. The demodulation control unit 231 determines in step 303 that m is 4
Or 2 if 4PSK or 2PSK in step 313
Is demodulated. If NO, m is 8 or 1 in step 304
If it is 6, go to step 305. If no, step 3
Go to 10. In step 305, calculations of TH8 and TH16 are performed. In step 306, the demodulation control unit 231 sends the threshold value TH16 for AM demodulation to the first identification reproduction circuit 136 and the second identification reproduction circuit 137. In steps 307 and 315, demodulation of the modified 16QAM and reproduction of the second data string are performed. In step 308, the error rate is checked. If the error rate is not good, the process returns to step 313 to perform 4PSK demodulation.

In this case, signal point 85.83 in FIG.
Is on the angle cos (ωt + nπ / 2), but signal point 84.86 is not on this angle. Therefore, the second data stream reproducing unit 233 shown in FIG. 21 sends carrier wave transmission information of the second data stream to the carrier wave reproducing circuit 131 so that the carrier wave is not extracted from the signal at the timing of the signal point 84.86.

The transmitter 1 intermittently sends a carrier timing signal based on the first data sequence, assuming that the second data sequence cannot be demodulated. Even if the second data string cannot be demodulated by this signal, the signal point 83.
85 is known. Therefore, the carrier can be reproduced by sending the carrier wave transmission information to the carrier reproducing circuit 131.

Next, when a signal of the modified 64QAM as shown in FIG. 23 is transmitted from the transmitter 1, returning to the flowchart of FIG. 24, it is determined in step 304 whether m is not 16 and in step 310, m is 64. Whether or not the following is checked, and if it is not the equidistant signal point method in step 311, the process proceeds to step 312. Here is the TH ₆₄ = the seek distance TH ₆₄ between signal points upon deformation _{64QAM (A 1 + A 2/} 2) / (A 1 + A 2), the same as the TH _16. However, the distance between signal points becomes smaller.

Assuming that the distance between signal points in the first sub-divided signal point group 181 is A ₃ , the first sub-divided signal point group 181
And the distance between the second sub-divided signal point group 182 and (A ₂ -2A ₃ )
When normalized, (A ₂ -2A ₃ ) / (A ₁ + A ₂ ). If this is defined as d ₆₄ , if d ₆₄ is equal to or less than the discrimination capability T ₂ of the second receiver 33, it cannot be discriminated. In this case, determination is made in step 313. If d ₆₄ is out of the allowable range, the process enters the 4PSK mode in step 313. If it is within the discrimination range, the process proceeds to step 305, and 16QAM of step 307 is performed.
Is demodulated. If the error rate is high in step 308, the process enters the 4PSK mode in step 313.

In this case, if the transmitter 1 transmits a modified 8QAM signal of signal points as shown in FIG. 25 (a), all signal points are on the angle of cos (2πf + n · π / 4). By the quadruple circuit, all carriers are degenerated to the same phase, so that the effect of simplifying the reproduction of the carrier is produced. In this case, 2 bits of the first data string can be demodulated even by the 4PSK receiver, which is not considered, and the second receiver 33
Can reproduce 1 bit of the second data string, 3 bits in total
Can be played.

Next, the third receiver 43 will be described. FIG.
6 is a block diagram of the third receiver 43, which has almost the same configuration as the second receiver 33 of FIG. The difference is that the third data string reproducing unit 234 is added and that the identification reproducing circuit has eight-level discrimination ability. Radius r _{3 of} antenna 42
Is larger than r _2, so that a signal having a shorter distance between signal points, for example, a 32-level QAM or a 64-level QAM can be demodulated. Therefore, in order to demodulate 64-value QAM, it is necessary for the first discriminating / reproducing circuit 136 to discriminate an 8-level level from the detection signal wave. In this case, there are seven threshold levels. Since one of them is 0, there are three thresholds in one quadrant.

As shown in the signal space diagram of FIG. 27, there are three thresholds in the first quadrant.

As shown in FIG. 27, there are three normalized thresholds, TH1 ₆₄ , TH2 ₆₄ and TH3 ₆₄ .

[0079] _{TH1 64 = (A 1 + A} 3/2) / (A 1 + A 2) TH2 64 = (A 1 + A 2/2) / (A 1 + A 2) TH3 64 = (A 1 + A 2 -A 3 / 2) / (A ₁ + A ₂ ).

By demodulating the received signal subjected to phase detection with this threshold value, the data of the third data sequence is demodulated in the same manner as the first data sequence and the second data sequence described with reference to FIG. As shown in FIG. 23, the third data string is, for example, the first data string.
Four signal points 201 and 20 in sub-divided signal group 181
By discriminating 2, 203 and 204, 4 values, that is, 2 bits
I can take it. Thus, demodulation of 6 bits, that is, modified 64-value QAM is enabled.

At this time, the demodulation control section 231 knows the values of m, A ₁ , A ₂ , and A _{3 from} the demodulation information included in the first data string of the first data string reproducing section 232, so that the threshold value TH is obtained.
1 ₆₄ and TH2 ₆₄ and TH3 feed ₆₄ and first regenerator circuit 136 calculates the to the second regenerator circuit 137, deformation 64QA
M demodulation can be performed reliably. In this case, since the demodulated information is scrambled, it is possible to make it possible for only a permitted receiver to demodulate 64QAM.
FIG. 28 shows a flowchart of the demodulation control section 231 of the modified 64QAM. Only the differences from the 16-value QAM flowchart of FIG. 24 will be described. Step 304 in FIG.
Then, step 320 is reached. If m = 32, step 322 is reached.
Is demodulated. If NO, m in step 321
= 64 or determined, since A ₃ can not be reproduced from the set value or less in step 323, towards the step 305, the same flow chart as in FIG. 24, demodulates the deformation 16QAM. Here, returning to step 323, if A ₃ is equal to or greater than the set value, the threshold is calculated in step 324, and
At step 25, the three threshold values are sent to the first and second discrimination / reproduction circuits, and at step 326, reproduction of the modified 64QAM is performed.
At 27, the first, second, and third data are reproduced. At step 328, if the error rate is high, the flow proceeds to step 305, and 16QAM demodulation is performed. If the error rate is low, 64QAM demodulation is continued.

Here, a carrier recovery method important for demodulation will be described. The present invention uses modified 16QAM and modified 64QA.
One of the features is that the first data string of M is reproduced by the 4PSK receiver. In this case, when a normal 4PSK receiver is used, it is difficult to reproduce the carrier wave and normal demodulation cannot be performed. To prevent this, some countermeasures are required on the transmitter side and the receiver side.

There are two types of methods according to the present invention. The first method is intermittent (2n-1)
This is a method of sending signal points on an angle of π / 4. The second method is a method in which substantially all signal points are arranged and transmitted on an angle of nπ / 8.

In the first method, as shown in FIG. 38, the signal points at four angles, π / 4, 3π / 4, 5π / 4, and 7π / 4, for example, the signal points 83 and 85 38, the synchronous time slots 452, 453, 454, and 455, which are intermittently transmitted in the time slot group 451 in the time chart of the transmission signal in FIG. 38, are set based on a certain rule. I do. Then, during this period, one of the eight signal points on the angle is always transmitted. In other time slots, an arbitrary signal point is transmitted. Then, the transmitter 1 arranges the above rule for transmitting the time slot in the data synchronization timing information section 499 shown in FIG. 41 and transmits the data.

The contents of the transmission signal in this case will be described in more detail with reference to FIG.
Time slot group 451 including 453, 454, 455
Form one unit data string 491, Dn.

Since the synchronization time slots are intermittently arranged in this signal based on the rules of the synchronization timing information, if this arrangement rule is understood, the carrier wave can be easily reproduced by extracting the information in the synchronization time slots. it can.

On the other hand, at the beginning of the frame of the data sequence 492, there is a synchronization area 493 indicated by S, which is composed of only synchronization time slots indicated by oblique lines. With this configuration, the amount of extracted information for carrier wave reproduction increases,
There is an effect that the carrier wave of the SK receiver can be surely and quickly reproduced.

The synchronization area 493 includes S1, S2, S3
, 498, 497, 498, etc., which contain a unique word for synchronization and the demodulation information described above. There is also a phase synchronization signal arrangement information section 499 indicated by I _T , which contains information such as information on arrangement intervals of the phase synchronization time slots and information on arrangement rules.

[0089] Since the carrier for the signal point has only a particular phase region of the phase synchronization time slot can be played on 4PSK receiver, since the content of the phase synchronization unit arranged information I _T is capable of reliably reproduce, after the information obtained Can reliably reproduce the carrier.

Next to the synchronization area 493 in FIG. 41, there is a demodulation information section 501, which contains demodulation information relating to a threshold voltage necessary for demodulating a modified multi-level QAM signal.
Since this information is important for demodulation of multi-level QAM, if demodulation information 502 is placed in the synchronization area as in the synchronization area 502 in FIG. 41, the demodulation information can be obtained more reliably.

FIG. 42 is a signal arrangement diagram when a burst signal is transmitted by the TDMA method. The difference from FIG. 41 is that a guard time 521 is provided between the data strings 492 and Dn and other data strings, and no transmission signal is transmitted during this period. A synchronization section 522 for synchronization is provided at the head of the data sequence 492. During this period, only the signal points having the phase of (2n-1) π / 4 are transmitted. Therefore, a carrier wave can be reproduced even by a 4PSK demodulator.
Thus, synchronization and carrier wave reproduction can be performed even in the TDMA system.

Next, the carrier recovery system of the first receiver 23 in FIG. 19 will be described in detail with reference to FIGS. 43 and 44. The received signal input in FIG. 43 enters the input circuit 24,
One of the demodulated signals synchronously detected by the synchronous detection circuit 541 is sent to the output circuit 542 and output, and the first data string is reproduced. The phase synchronization section arrangement information section 499 of FIG. 41 is reproduced by the extraction timing control circuit 543, and it is known at which timing the signal of the (2n-1) π / 4 phase synchronization section comes in. Phase synchronization control signal 56
1 is sent. The demodulated signal is sent to the multiplication circuit 545,
The frequency is multiplied and sent to the carrier recovery control circuit 54. FIG.
The signal 562 includes a signal of the true phase information 563 and a signal other than the signal 562 like the signal 562 of FIG. As shown by hatching in the timing chart 564, a phase synchronization time slot 452 including signal points having a phase of (2n-1) π / 4 is intermittently included. This is sampled by the carrier reproduction control circuit 544 using the phase synchronization control signal 564 to obtain a phase sample signal 565. By sampling and holding this, a predetermined phase signal 566 is obtained. This signal passes through the loop filter 546, and the VCO 5
The carrier wave is sent to 47 and reproduced, and sent to the synchronous detection circuit 541. In this manner, signal points having a phase of (2n-1) π / 4 as shown by oblique lines in FIG. 39 are extracted. Based on this signal, an accurate carrier wave can be reproduced by the quadrupling method. At this time, a plurality of phases are reproduced, but by inserting a unique word into the synchronization section 496 in FIG. 41, the absolute phase of the carrier can be specified.

When transmitting the modified 64QAM signal as shown in FIG. 40, the phase synchronization time slot 452 and the phase synchronization time slot 452 are set only for the signal points in the phase synchronization area 471 indicated by the oblique lines having a phase of approximately (2n−1) π / 4. The transmitter sends 452b and the like. For this reason, a carrier cannot be reproduced by a normal 4PSK receiver, but the first receiver 23 of 4PSK has an effect that the carrier can be reproduced by providing the carrier recovery circuit of the present invention.

The above is the case where the carrier recovery circuit of the Costas system is used. Next, a case where the present invention is used in an inverse modulation type carrier recovery circuit will be described.

FIG. 45 shows an inverse modulation type carrier recovery circuit of the present invention. The demodulated signal is reproduced by the synchronous detection circuit 541 from the received signal from the input circuit 24. On the other hand, the input signal delayed by the first delay circuit 591 is input to the four-phase modulator 5.
At 92, the signal is inversely demodulated by the demodulated signal to become a carrier signal. The carrier signal that has passed through the carrier recovery control circuit 544 is sent to the phase comparator 593. On the other hand VCO
The reproduced carrier from 547 is supplied to the second delay circuit 594 by the
The phase is compared with the above-mentioned inversely modulated carrier signal by the phase comparator 593, the phase difference signal is supplied to the VCO 547 through the loop filter 546, and the carrier having the same phase as the received carrier is reproduced. In this case, similarly to the Costas-type carrier recovery circuit of FIG.
43 samples the phase information of only the signal points in the hatched area in FIG.
However, the carrier can be reproduced by the 4PSK modulator of the first receiver 23.

Next, a description will be given of a method of reproducing a carrier by a 16-times multiplication method. Transmitter 1 in FIG. 2 performs modulation and transmission by arranging signal points of modified 16QAM at a phase of nπ / 8 as shown in FIG. First receiver 2 in FIG.
In the case of No. 3, by using a Costas type carrier recovery circuit having a 16 multiplication circuit 661 as shown in FIG.
The carrier can be regenerated. 4 by the 16-multiplier circuit 661.
A signal point having a phase of nπ / 8, such as 6, is degenerated to the first quadrant, so that the carrier can be reproduced by the loop filter 546 and the VCO 541. By arranging the unique word in the synchronization area, the absolute phase can be extracted from the 16 phases.

Next, the configuration of the 16 multiplication circuit will be described. From the demodulated signal, a sum signal,
A difference signal is created and multiplied by a multiplier 664 to obtain cos2θ
Create The multiplier 665 produces sin2θ.
These are multiplied by a multiplier 666 to generate sin4θ.

Similarly, a sum circuit 667, a difference circuit 668 and a multiplier 670 calculate s from sin2θ and cos2θ.
Create in8θ. Con8θ is created by the sum circuit 671, the difference circuit 672, and the multiplier. Then, by making sin16θ by the multiplier 674, 16 times multiplication can be performed.

By the 16-times multiplication method described above, FIG.
There is a great effect that the carrier waves of all the signal points of the modified 16QAM signal having such a signal point arrangement can be reproduced without extracting a specific signal point.

A modified 64Q arranged as shown in FIG.
Although the carrier of the AM signal can be reproduced, some signal points are slightly shifted from the synchronization area 471, so that the error rate during demodulation increases.

As a countermeasure, there are two methods. One is to not transmit a signal at a signal point outside the synchronization area. This has the effect of reducing the amount of information but simplifying the configuration.
Another is to provide a synchronization time slot as described with reference to FIG. By transmitting signal points such as the synchronous phase regions 471 and 471a having a phase of nπ / 8 indicated by oblique lines during a synchronous time slot in the time slot group 451, accurate synchronization can be achieved during this period. Therefore, the phase error is reduced.

As described above, the modified 16QA by the 4PSK receiver has a simple receiver configuration by the 16 multiplication method.
There is a great effect that a carrier wave of a signal of M or modified 64QAM can be reproduced. Further, when a synchronization time slot is further set, an effect of increasing the phase accuracy at the time of carrier reproduction of the modified 64QAM can be obtained.

As described in detail above, by using the transmission apparatus of the present invention, a plurality of data can be simultaneously transmitted in a single radio wave band in a hierarchical structure.

In this case, by setting three-layered receivers having different reception sensitivity and demodulation capability for one transmitter, there is an advantage that a data amount commensurate with the investment of the receiver can be demodulated. First, a human receiver who purchases a small antenna and a low-resolution but low-cost first receiver can demodulate and reproduce the first data string. Next, a receiver who has purchased a medium-sized antenna and a medium-cost high-cost second receiver can reproduce the first and second data strings. A person who has purchased a large-sized antenna and a high-resolution third receiver having a high resolution can demodulate and reproduce all of the first, second, and third data strings.

If the first receiver is a home digital satellite broadcast receiver, the receiver can be realized at a low price that can be accepted by many ordinary consumers. Although the second receiver initially requires a large antenna and is expensive, it is not acceptable to consumers in general, but it is meaningful for those who want to watch HDTV. The third receiver requires a rather large industrial antenna until the satellite power increases, and is not practical for home use and is initially suitable for industrial use. For example, if an ultra-high resolution HDTV signal is transmitted and transmitted to various movie theaters by satellite, the movie theater can be digitized by video. In this case, there is also an effect that operating costs of movie theaters and video theaters are reduced.

As described above, when the present invention is applied to TV transmission, there is a great effect that three image quality video services can be provided in one radio frequency band, and that they are compatible with each other. In the embodiment, examples of 4PSK, modified 8QAM, modified 16QAM, and modified 64QAM have been described.
M and 256 QAM can also be realized. Also, 8PSK or 16
PSK and 32PSK can also be implemented. Further, in the embodiment, the example of the satellite transmission has been described, but it goes without saying that the same can be realized by the terrestrial transmission or the wired transmission.

(Embodiment 2) In Embodiment 2, the physical hierarchical structure described in Embodiment 1 is logically further divided by, for example, differentiating the error correction capability, and a logical hierarchical structure is added. In the case of the first embodiment, the respective hierarchical channels have different electric signal levels, that is, different physical demodulation capabilities. On the other hand, the second embodiment differs in logical reproduction capability such as error correction capability. Dividing the data in the hierarchy channel specifically, for example D _1, for example, in two of D _1-1 and D _1-2, error correction capability of one example D _1-1 data of the divided data D
Higher than _1-2 data, than to differentiate the error correction capability, since the error after adjusting capability data D _1-1 and D _{1 -2} in demodulation reproduction are different, lower the C / N value of the transmission signal If the signal level cannot be reproduced by D _1-2 ,
_1-1 means that the original signal can be reproduced within the set error rate. This can be called a logical hierarchical structure.
In other words, by dividing the data of the modulation hierarchical channel, and by differentiating the magnitude of the inter-code distance of error correction such as the use of an error correction code and a product code, a logical hierarchical structure based on the error correction capability is added, Finer hierarchical transmission is possible.

[0108] With this, D ₁ channel D _1-1,
Two sub channels D _1-2, D ₂ channel D _2-1, increase to two sub channels D _2-2.

This will be described with reference to FIG. 85 showing the C / N value of the input signal and the hierarchical channel number.
_1-1 can be reproduced with the lowest input signal. This CN value is d
Then, when CN = d, D _1-1 is reproduced, but D _1-2 ,
D _2-1 and D _2-2 are not reproduced. Next, when CN = c or more, _D1-2 is further reproduced. When CN = b, _D2-1 is added, and when CN = a, _D2-2 is added. As described above, as the CN increases, the total number of reproducible hierarchies increases. Conversely, as the CN decreases, the total number of reproducible hierarchies decreases. The transmission distance and the reproducible CN shown in FIG.
This will be described with reference to a value diagram. Generally, as the transmission distance becomes longer as shown by a solid line 861 in FIG. 86, the C / N value of the received signal decreases. The distance from the transmitting antenna at the point where CN = a described in FIG. 85 is La, and when CN = b, Lb,
Lc when CN = c, Ld when CN = d, L when CN = e
e. Sakoi area than the distance from the transmitting antenna Ld only D _1-1 channel, as described in FIG. 85 can be reproduced. Region 8 coverage of the D _1-1 shaded
Indicated at 62. As is clear from the figure, the _D1-1 channel can be reproduced in the widest area. Similarly, the _D1-2 channel can be reproduced in an area 863 within a distance Lc from the transmitting antenna. The distance in the range of less than Lc 862 can also be reproduced D _1-1 channel for also included. Similarly, area 8
In the area 64, the _D2-1 channel can be reproduced, and in the area 865, the _D2-2 channel can be reproduced. In this way,
Hierarchical transmission in which the number of transmission channels decreases step by step with the deterioration of the CN value is possible. By separating the data structure into a hierarchical structure and using the hierarchical transmission of the present invention, there is an effect that a hierarchical transmission in which the data amount gradually decreases as the C / N deteriorates like analog transmission becomes possible. .

Next, a specific configuration will be described. Here, an embodiment of two physical layers and two logical layers will be described. FIG. 87 is a block diagram of the transmitter 1. Since this is basically the same as the block diagram of the transmitter of FIG. 2 described in the first embodiment, detailed description is omitted, but the difference is that an error correction code encoder is added. This is abbreviated as ECC encoder. The separation circuit 3 has four outputs of _1-1 , _1-2 , _2-1 and _2-2 , and inputs signals of D1-1, D1-2, D2-1 and D2-2. Separate into two signals and output. Among, D _1-1, D _1-2 signal is first 1EC
The signals are input to the C encoder 871a and sent to the main ECC encoder 872a and the sub ECC encoder 873a, respectively, where they are encoded for error correction.

Here, the main ECC encoder 872a is
It has a stronger error correction capability than the CC encoder 873a. Therefore, as described in the graph of CN- hierarchical channel of FIG. 85, upon demodulation reproduction, D _1-1 channel even at low C / N value than D _1-2 channel D
_1-1 can be reproduced below the reference error rate. D _1-1 is D _1-
It has a logical hierarchical structure that is more resistant to a decrease in C / N than ₂ . Error-corrected D _1-1, D _1-2 signal combiner 874a
Are combined with the D ₁ signal and input to the modulator 4. on the other hand,
The D _2-1 and D _2-2 signals are respectively transmitted to the main encoder 872b and the sub ECC encoder 87 in the second ECC encoder 871b.
3b, and is error-correction-coded by the synthesizer 874b.
_{The two} signals are combined and input by the modulator 4. Main EC
The C encoder 872b has a higher error correction capability than the sub ECC encoder 873b. In this case, the modulator 4 generates a hierarchical modulation signal from the D ₁ signal and the D ₂ signal, and the modulation signal is transmitted from the transmission unit 5. As described above, the transmitter 1 of FIG. 87 has a two-layer physical hierarchical structure of D ₁ and D ₂ by the modulation described in the first embodiment. This description has already been given. Next, _D1-1 and _D1-2 or _D2-1 , D2-1
Each of _2-2 has a logical hierarchical structure of two layers.

Next, the state of receiving this signal will be described.
FIG. 88 is a block diagram of the receiver. The basic configuration of the second receiver 33 that has received the transmission signal of the transmitter of FIG. 87 is substantially the same as that of the second receiver 33 described in FIG. 21 of the first embodiment. The difference is that ECC decoders 876a and 876b are added. In this case, an example of QAM modulation / demodulation is shown.
SK, PSK, or FSK modulation / demodulation may be used.

In FIG. 88, the received signal is reproduced as D ₁ and D ₂ signals by the demodulator 35 and
a, by 3b, each D _1-1 and D _1-2, D _2-1, 4 of D _2-2
One signal is generated and input to the first ECC decoder 876a and the second ECC decoder 876b. In a 1ECC decoder 876a, D _1-1 signal is mainly ECC decoder 8
The error is corrected by 77a and sent to the combining unit 37. On the other hand, D _1-2 signal is sent to the error-corrected combining unit 37 by sub ECC decoder 878a. Similarly, the second ECC
In the decoder 876b, the D _2-1 signal is used in the main ECC decoder 877b, and the D _2-2 signal is used in the sub ECC decoder 8
The error is corrected at 78b and input to the combining unit 37. The error corrected D _1-1 , D _1-2 , D _2-1 , and D _2-2 signals become one signal in the synthesizing unit 37 and are output from the output unit 36.

In this case, D _1-1 is D
From _1-2, also D _2-1 are as described in FIG. 85 because of high error correction capability than D _2-2, a predetermined error rate can be obtained even at lower state C / N value of the input signal , The original signal can be reproduced.

More specifically, main ECC decoders 877a and 87
7b and a method of differentiating the error correction capability between the sub ECC decoders 878a and 878b. When a standard inter-code distance coding method such as Reed-Solomon code or BCH code is used for the sub-ECC decoder, the product code or long coding method of both Reed-Solomon code and Reed-Solomon code is used for the main ECC decoder. The error correction capability can be made different by using a coding method having a large inter-code distance of the used error correction. Thus, a logical hierarchical structure can be realized. Since various methods are known for increasing the inter-code distance, other methods are omitted. The present invention can basically apply any method.

Here, the logical hierarchical structure is represented by C / N in FIG.
This will be described with reference to a relationship diagram between the error rate after error correction. In FIG. 89, a straight line 881 shows the relationship between the C / N of the _D1-1 channel and the error rate, and a straight line 882 shows the D / D
The relationship between the C / N of channel _1-2 and the error rate after correction is shown.

As the C / N value of the input signal decreases, the error rate of the corrected data increases. Below a certain C / N value, the error rate after error correction does not fall below the reference error rate Eth at the time of system design, and the original data is not reproduced normally. Now, C / N can not demodulate the D ₁ channel when: e as gradually indicated when Yuku raising the C / N D _1-1 signal of linear 881 in FIG. 89. Although e ≦ C / N <demodulation when D ₁ channel d may, D _1-1 channel error rate exceeds the Eth, can not be reproduced original data correctly.

[0118] C / N = time of d, for D _1-1 is error correcting capability higher than the D _1-2, point error rate after error correction 8
As shown at 85d, it becomes less than Eth, and the data can be reproduced. On the other hand, the error correction capability of D _1-2 is error rate after correcting for the error rate after correction for not high enough D _1-1 is not low enough D _1-1 can not be reproduced for greater than E ₂ and Eth. Therefore only this case D _1-1 can be reproduced.

When C / N is improved and C / N = C,
Since the error rate after error correction of D _1-2 reaches Eth, as shown at point 885C, it can be reproduced. This is a point D _2-1, D _2-2, i.e. D ₂ channel demodulation in uncertainty. With the improvement of C / N, D ₂ channel is to reliably demodulated at C / N = b '.

[0120] When the further C / N becomes improved C / N = b, decreased error rate of D _2-1 until Eth as shown in point 885B, D _2-1 will be able to play .
At this time, the error rate of D _2-2 can not be reproduced for greater Eth. C / N = error rate of D _2-2 as shown in the point 885a becomes a is the reduced D _2-2 channel until the Eth becomes possible play.

As described above, by using the error correction capability differentiation, the physical hierarchy D ₁ and D ₂ channels can be further divided into two logical hierarchies into two logical hierarchies, so that a total of four hierarchical hierarchies can be transmitted. .

In this case, the data structure is changed to a hierarchical structure in which a part of the original signal can be reproduced even if the data of the higher hierarchy is lost, and by combining with the hierarchical transmission of the present invention, the C / N like analog transmission is realized. This has the effect of enabling hierarchical transmission in which the data amount gradually decreases with the deterioration of. In particular, image compression technology in recent years is rapidly advancing, so when image compression data is made into a hierarchical structure and combined with hierarchical transmission, video with much higher image quality is transmitted between the same points than analog transmission, and at the same time, analog transmission is performed. As in transmission, it is possible to receive in a wide area while lowering the image quality according to the received signal level in stages. As described above, the effect of hierarchical transmission, which has not been achieved in conventional digital video transmission, can be obtained while maintaining high digital image quality.

(Embodiment 3) Hereinafter, a third embodiment of the present invention will be described with reference to the drawings.

FIG. 29 is an overall view of the third embodiment. Embodiment 3 shows an example in which the transmission apparatus of the present invention is used for a digital TV broadcasting system. An input video 402 having an ultra-high resolution is input to an input unit 403 of a first image encoder 401, The data stream is separated into a data stream, a second data stream, and a third data stream, and compressed and output by the compression circuit 405.

The other input images 406, 407, 408 are compressed and output by the second image encoders 409, 410, 411 having the same configuration as the first image encoder 401.

Of these four sets of data, the four sets of signals in the first data string are time-multiplexed by the first multiplexer 413 of the multiplexer 412 by the TDM method or the like, and are used as the first data string. , To the transmitter 1.

The whole or a part of the signal group of the second data string is multiplexed by the multiplexer 414 and sent to the transmitter 1 as the second data string. Further, all or a part of the signal group of the third data string is multiplexed by the multiplexer 415,
The data is sent to the transmitter 1 as a data string.

In response to this, the transmitter 1 performs the modulation described in the first embodiment on the three data strings by the modulator 4, sends the data string to the satellite 10 by the antenna 6 and the transmission path 7 by the transmitter 5, and sends the data to the satellite 10 by the repeater 12. , The first receiver 23 and the like.

In the first receiver 23, the signal is received by the small-diameter antenna 22 having the radius r ₁ through the transmission line 21, and only the first data sequence in the received signal is reproduced by the first data sequence reproducing unit 232.
The first image decoder 421 outputs low-resolution video outputs 425 and 4 such as an NTSC signal or a wide NTSC signal.
26 is reproduced and output.

In the second receiver 33, the signal is received by the medium-diameter antenna 32 having a radius of r ₂ ,
The data stream reproducing unit 233 reproduces the first data stream and the second data stream, and the second image decoder 422 reproduces the HDT stream.
A high-resolution video output 427 or a video output 425 or 426 such as a V signal is reproduced and output.

In the third receiver 43, the data is received by the large-diameter antenna 33 having a radius r ₃ ,
The data stream reproducing unit 233 and the third data stream reproducing unit 234 reproduce the first data stream, the second data stream, and the third data stream, and provide an ultra-high resolution HDTV or the like for a video theater or a movie theater. The video output 428 is output. Video output 4
25, 4266, 427 can also be output. A general digital TV broadcast is broadcast from the digital transmitter 51 and, when received by the first receiver 23, is output as a low-resolution video output 426 such as NTSC.

Next, the configuration will be described in detail based on the block diagram of the first image encoder 401 in FIG. The super high resolution video signal is input to the input unit 403 and sent to the separation circuit 404. The separation circuit 404 separates the signals into four signals by a sub-band coding method. A horizontal low-pass filter 451 and a horizontal high-pass filter 452 such as QMF separate the signal into a horizontal low-frequency component and a horizontal high-frequency component. The components are output by a vertical low-pass filter 455 and a vertical high-pass filter 456, respectively.
_L V _L signal and a horizontal low-vertical high frequency signal is separated into H _L V _H signal for short, the subsampling unit 457 and 458,
The sampling rate is reduced and sent to the compression unit 405.

The horizontal high-frequency component is calculated by the vertical low-pass filter 4.
The 59 and vertical high-pass filter 460, the horizontal high band vertical low frequency signal, for short and _H H V _L signal, the horizontal high band vertical low frequency signal is separated into _H H L _H signal for short, sub-sampling unit 461 , The sampling rate is reduced and sent to the compression unit 405.

In the compression section 405, the H _L V _L signal is optimally compressed by DCT or the like in the first compression section 471, and the first output section 472
It is output as a first data string.

[0135] H _L V _H signal is sent to the second output unit 464 are compressed by the second compression unit 473. H _H V _L signal is sent to the second output unit 464 are compressed by the third compressor unit 463. H
_H V _H signal is high-resolution image symbols by separating circuit 465 (H
_{HV H1} ) and an ultra-high resolution video signal (H _H V _H2 ). H _H V _H1 is sent to the second output unit 464, and H _H V _H 2 is sent to the third output unit 468.

Next, the first image decoder 4 will be described with reference to FIG.
21 will be described. The first image decoder 421 receives the output from the first receiver 23 and the first data sequence, that is, D _1, at the input unit 5.
The decompression unit 503 after solving scrambled by de-scrambler 502 and input to 01, the aforementioned H _L V _L signal to change the screen ratio by screen ratio changing circuit 504 and an output section 505 after extension NTSC signal of the image 506, NT
An image 507 of a stripe screen, an image 508 of a full screen of a wide TV, or an image 509 of a side panel screen of a wide TV are output by the SC signal. In this case, two types of scanning lines, non-interlaced or interlaced, can be selected. In the case of NTSC, 525 scanning lines and 1,050 scanning lines by double writing are obtained. In addition, the digital transmitter 5
When a general digital TV broadcast of 4PSK from 1 is received, a TV image can be demodulated and reproduced by the first receiver 23 and the first image decoder 421. Next, the second image decoder will be described with reference to the block diagram of the second image decoder in FIG. First, the D ₁ signal from the second receiver 33 is input from the first input unit 521 and is expanded by the first expansion unit 522.
The sampling rate is doubled by the oversampling unit 523, and H _{L is set} by the vertical low-pass filter 524.
The _VL signal is reproduced. The D ₂ signal is input from the second input unit 530 and separated into three signals by the separation circuit 531.
The second extension part 532, the third extension part 533, and the third extension part 5
34, the sampling rate is doubled by the oversampling units 535, 536, and 537.
38, a vertical low-pass filter 539, and a vertical high-pass filter 540. The _{HL VL} signal and the _HL V _H signal are added by the adder 525, and the
1 and a horizontal low-pass video signal by the horizontal low-pass filter 542, which are sent to the adder 543. H _{H VL} signal and H
_{The H} V _H 1 signal is added by an adder 526, becomes a horizontal high-frequency video signal by an oversampling unit 544 and a horizontal high-pass filter 545, and becomes HDT by an adder 543.
The output unit 546 outputs a high-resolution video signal HD signal such as V, and outputs an image output 547 such as HDTV. In some cases, an NTSC signal is also output.

[0137] Figure 33 is D ₁ signal is a block diagram of a third image decoder D ₂ signal from the first input section 521 HD signal reproduced in the previous step by high-frequency image decoder 527 inputted from the second input unit 530 Is done. D ₃ signal is extended, descrambling, and the synthesized H _H V _H 2 signal is reproduced by the third input from the input unit 551 ultrahigh frequency band image decoder 552. This signal is synthesized with the HD signal by the synthesizer 553 to become an ultra-high resolution TV signal and an S-HD signal, and the output unit 5
An ultra-high resolution video signal 555 is output from 54.

Next, a specific multiplexing method of the multiplexer 401 mentioned in the description of FIG. 29 will be described. Figure 34 is a data sequence diagram, the first data stream, D ₁ and the second data string, D ₂ and the third data string D ₃ into six NTSC channel L1, L
2, L3, L4, L5, L6, six HDTV channels M1 to M6, and six S-HDTV channels H1 to H
FIG. 6 illustrates how to place 6 on the time axis during the period T. Figure 34 is a L1 from L6 to D ₁ signal to the first period T in which to place the time multiplexed by TDM scheme or the like. _HL V _L of the first channel in the domain 601 of D ₁
Send a signal. The domain 602 of D ₂ signal then first channel HDT in the time domain corresponding to the first channel
Difference information M1 that is between V and NTSC, sends the above-mentioned H _L V _H signal and _H H V _L signal and _H H V _H 1 signal. Also the D ₃ signal domain 603 super HDTV first channel
Difference information H1, i.e. _H H V _H over 2H described with reference to FIG. 30
Send 1

The case where the TV station of the first channel is selected will be described. First, a general receiver having a small antenna, a first receiver 23 and a first image decoder 421 system can obtain the NTSC or wide NTSC TV signal shown in FIG. Next, a specific receiver having a medium-sized antenna, a second reception transceiver 33 and a second image encoder 422 selects the channel 1 when the first data stream, the domain 60 of D ₁ is selected.
1 and a second data string, HD having the same program content as the NTSC program of the channel 1 signal synthesized and the D ₂ domains 602
Obtain a TV signal.

Some recipients such as movie theaters having a large antenna, a third receiver 43 capable of multi-level demodulation, and a third image decoder 423 have a domain 601 of D ₁ and a domain 602 of D ₂ .
And the signal of domain 603 of D ₃
A super-resolution HDTV signal of the image quality for a movie theater is obtained with the same program contents as NTSC. Other channels 2 to 3 are reproduced in the same manner.

FIG. 35 shows the structure of another domain. First, the first channel of NTSC is arranged in L1. Domain of the first time domain of L1 is D ₁ signal 60
In the first part, information S11 including the descrambling information between NTSC and the demodulation information described in the first embodiment is included. Next, the first channel of HDTV is L1 and M
It is divided into ones. M1 is HDTV and NTSC
, And is included in both domain 602 and domain 611 of D ₂ . In this case, 6Mbps NT
When the SC compression signal is adopted and accommodated in L1, the bandwidth of M1 is doubled to 12 Mbps. When L1 and M1 are combined, a band of 18 Mbps can be demodulated and reproduced from the second receiver 33 and the second image decoder 423. On the other hand, using a currently proposed compression method, a HDTV band of about 15 Mbps is used.
A compressed signal can be realized. Therefore, HDTV and NTSC can be simultaneously broadcast on channel 1 in the arrangement shown in FIG. In this case, HDTV cannot be reproduced on channel 2. S21 is HDTV descrambling information. The super HDTV signal is divided into L1, M1, and H1 and broadcast. The difference information of the super HDTV is using the domain 603,612,613 of D _3, 6M an NTSC
When set to bps, a total of 36 Mbps can be sent, and if the compression is increased, a super HDTV signal of about 2,000 scanning lines of movie theater quality can be transmitted.

[0142] arrangement of FIG. 36 shows a case where the transmission of the super HDTV signal is occupied six times domains D _3. When NTSC compressed signal is set to 6Mbps 9
The transmission rate of 54 Mbps can be doubled. Therefore, super HDTV with higher image quality can be transmitted.

The above is the case where one of the horizontal and vertical polarization planes of the radio wave of the transmission signal is used. Here, by using two horizontal and vertical polarization planes, the frequency utilization efficiency is doubled. This will be described below.

[0144] Figure 49 is a horizontal polarization signal D _V1 of the first data stream
And D _V2 and D 2 of the vertical polarization signal D _H1 and the second data string.
_H2, shows a signal arrangement diagram of D _V3 and D _H3 of the third data string. In this case, the vertical polarization signal DV1 of the first data _stream contains a low frequency TV signal such as NTSC, and the horizontal polarization signal _DH1 of the first data stream contains a high frequency TV signal. Therefore, the first receiver 23 having only the vertically polarized antenna has the NTSC
Etc. can be reproduced. On the other hand, the first receiver 23 having the vertical and horizontal polarization antennas is, for example, L ₁
It is possible to obtain the combined HDTV signal M ₁ signal.
That is, when the first receiver 23 is used, NTSC on the one hand and TSC and HD on the other hand depend on the capability of the antenna.
Since the TV can be reproduced, there is a great effect that the two systems are compatible.

FIG. 50 shows a case where the TDMA system is used. A synchronization section 731 and a card section 741 are provided at the head of each data burst 721. Further, a synchronization information section 720 is provided at the head of the frame. In this case, each time slot group is assigned one channel. For example, in the first time slot 750, NTSC, HDTV, and super HDTV of the same program on the first channel can be transmitted. Each time slot 7
50-750e are completely independent. Therefore, when a specific broadcast station broadcasts in a TDMA system using a specific time slot, there is an effect that NTSC, HDTV, and super HDTV can be broadcast independently of other stations. In the case where the receiving side is also a horizontally polarized antenna and has the first receiver 23, if the NTSC TV signal is a dual polarized antenna, HDT
V can be played. The second receiver 33 can reproduce a low-resolution super HDTV. With the third receiver 43, the super HDTV signal can be completely reproduced. As described above, a compatible broadcasting system can be constructed. in this case,
With the arrangement as shown in FIG. 50, time multiplexing of continuous signals as shown in FIG. 49 is possible instead of the burst-like TDMA method.
With the signal arrangement shown in FIG. 51, a higher resolution HDTV signal can be reproduced.

As described above, according to the third embodiment, there is a remarkable effect that it is possible to realize digital TV broadcasting compatible with three signals of an ultra-high resolution HDTV, HDTV and NTSC-TV. In particular, when transmitted to a movie theater or the like, there is a new effect that images can be digitized.

Here, the modified QAM according to the present invention is
Called AM, a specific error rate will be described.

First, the error rate of 16 SRQAM is calculated. FIG. 99 is a vector diagram of signal points of 16 SRQAM. In the first quadrant, in the case of 16QAM, the intervals between the 16 signal points such as the signal points 83a, 83b, 84a, 85, and 83a are equally spaced, and all are 2δ.

The signal point 83a of 16QAM corresponds to the coordinate axis I.
The axis is at a distance of δ from the Q axis. Here, in the case of 16 SRQAM, if n is defined as a shift value, the signal point 83a shifts and the distance from the coordinate axis is changed to the signal point 8 at the position of nδ.
Move to 3. In this case, n is 0 <n <3. The other signal points 84a and 86a also shift to the positions of the signal points 84 and 86. If the error rate of the first data string is Pe1,

[0150]

(Equation 1)

When the error rate of the second data string is Pe2

[0152]

(Equation 2)

Is obtained. Next, 36 SRQAM or 32
Calculate the SRQAM error rate. Figure 100 shows 36
It is a signal vector diagram of SRQAM. In the first quadrant, the distance between signal points of 36QAM is defined as 2δ.

The signal point 83a of 36QAM is δ from the coordinate axis.
At a distance. When the signal point 83a reaches 36 SRQAM, the signal point 83a shifts to the position of the signal point 83 and has a distance of nδ from the coordinate axis. Each signal point is shifted to signal points 83, 8
4, 85, 86, 97, 98, 99, 100, 101. A signal point group 90 consisting of nine signal points is regarded as a single signal point, deformation received in 4PSK receiver, the error rate in the case of reproducing the first data column only D ₁ over a Pe1, the signal point group 90 And the error rate when the second data stream D ₂ is reproduced is Pe2.

[0155]

(Equation 3)

Is obtained. In this case, the C / N to error rate diagram of FIG. 101 shows an example in which the relationship between the error rate Pe and the C / N of the transmission system is calculated. Curve 900 shows the conventional 32QAM error rate for comparison. Straight line 905
Indicates a straight line having an error rate of 10 to the power of -1.5. The first case where the shift amount n of the SRQAM of the present invention is 1.5
Error rate of the hierarchy D ₁ has the effect that the next curve 901a, error rate D ₁ also drops 5dB is C / N value for 32QAM curve 900 in 10 ^-1.5 can be reproduced with equal error rate.

[0157] Then n = 1.5 second error rate of the hierarchy D ₂ in the case of the shown by the curve 902a. When the error rate is 10 ^−1.5 , reproduction cannot be performed at the same error rate unless the C / N is increased by 2.5 dB as compared with 32QAM indicated by the curve 900. Curves 901b and 902b have n = 2.
D ₁ and D ₂ in the case of 0 are shown. Curve 902C shows a D _2. To summarize, the error rate is 10 -1.5.
When 22n = 1.5, 2.0, 2.5 in the value of the power,
Compared to 32QAM, D ₁ is improved by 5, 8, and ₁₀ dB, and D ₂ is deteriorated by 2.5 dB.

In the case of 32 SRQAM, when the shift amount n is changed, a first error rate required to obtain a predetermined error rate is obtained.
The C / N values of the data sequence D ₁ and the second data sequence D ₂ are shown in the relationship diagram between the shift amount n and the C / N in FIG. 103. As is clear from FIG. 103, if n is 0.8 or more, a difference in C / N value required for hierarchical transmission, that is, transmission of the first data sequence D ₁ and the second data sequence D ₂ is generated, It can be seen that the effect of the present invention occurs. Therefore, in the case of 32 SRQAM, it is effective under the condition of n> 0.85. The error rate in the case of 16 SRQAM is as shown in the relationship between C / N and error rate in FIG. In FIG. 102, a curve 900 indicates an error rate of 16QAM. Curve 901a, 901b, 901c each exhibit error rate when the first data stream D ₁ of the n = 1.2,1.5,1.8. Curves 902a, 902b,
902c each of the second data stream D ₂ n = 1.2,1.
5 shows error rates in the case of 1.8.

The relationship between shift amount n and C / N in FIG. 104 is the first data string D ₁ required to obtain a specific error rate when shift amount n is changed in the case of 16 SRQAM.
If it shows a value of the second data stream D ₂ of the C / N.
As is clear from FIG. 104, in the case of 16 SRQAM, n>
It can be seen that if the ratio is 0.9, the hierarchical transmission of the present invention becomes possible. From the above, if n> 0.9, hierarchical transmission is established.

Here, a specific example in which the SRQAM of the present invention is applied to digital TV terrestrial broadcasting will be described. FIG.
05 shows a relational diagram between the distance between the transmitting antenna and the receiving antenna during terrestrial broadcasting and the signal level. Curve 911 shows the signal level of the receiving antenna when the height of the transmitting antenna is 1250 ft. First, it is assumed that the required error rate of the transmission system required in the digital TV broadcasting system under consideration is 10 −1.5. Region 912
Indicates a noise level, and a point 910 indicates a reception limit point of the conventional 32QAM system at a point where C / N = 15 dB.
Digital HDT at the point of L = 60 miles
V broadcast can be received. However, there is a problem that when the C / N is reduced due to deterioration of reception conditions such as weather, HDTV reception becomes suddenly impossible. Also, due to the influence of topography and buildings, fluctuations of at least about 10 dB are expected, and
Not all points within the radius of ile can be received. In this case, unlike analog, video cannot be transmitted completely in digital. Therefore, the service area of the conventional digital TV broadcasting system is uncertain.

[0161] On the other hand, if the 32SRQAM of the present invention, it is possible to send only the high-frequency component of the first hierarchical D ₁ sends a resolution TV components in the NTSC or the like, HDTV in the second layer D ₂ as described above. For example, in FIG. 105, the service area of the first layer is expanded to a point 70 miles as shown by a point 910a, and the service area of the second layer is 55 miles as shown at 910b.
Retreat to the point. The service area diagram of 32 SRQAM in FIG. 106 shows the difference in the area of the service area in this case. FIG. 106 illustrates FIG. 53 more specifically. In FIG. 106, regions 708, 703a, and 703
b, 712 respectively indicate the service area of 32QAM the conventional method, first service area hierarchy D _1, the service area of the second layer D _2, the service area of the neighboring analog stations.

That is, in the conventional 32QAM, a service area of approximately 60 miles each can be set. But,
In fact, the reception condition was extremely unstable near the reception limit area due to changes in weather and terrain conditions.

However, using the 32 SRQAM of the present invention,
By transmitting the NTSC grade middle / low range TV component on the first layer D ₁ and transmitting the HDTV high band TV component on the second layer D ₂ , the radius of the high resolution grade service area is reduced as shown in FIG. Although the distance is reduced by 5 miles, the radius of the service area of the medium and low resolution grade is increased by 10 miles or more.

As a result, first, in the conventional method,
By applying the SRQAM method of the present invention even in an unreceivable area that existed in an area where reception conditions are poor,
At least within the set service area, transmission can be performed so that almost all receivers can receive TV broadcasts at medium to low resolution grades. Accordingly, the unreceivable area in the unreceivable area such as a building or a lowland and the area which is interfered by an adjacent analog station is greatly reduced, and the number of recipients is accordingly increased.

Secondly, in the conventional system, only a receiver having an expensive HDTV receiver and a receiver can be received, so that only a part of the receiver can be viewed in the service area. However, in the present invention, the conventional NTSC, PAL, SECAM
Receptionists who have a conventional TV receiver of the digital TV system can increase the digital HDTV by adding only digital receivers.
There is an effect that a broadcast program can be received although it is of NTSC grade. Therefore, the receiver can view the program with less economic burden. At the same time, the total number of receivers increases, so that the TV sender can obtain more viewers.
The social effect that management as V business becomes more stable is produced.

Third, the area of the receiving area of the middle and low resolution grade is 36% larger than that of the conventional system when n = 2.5. The number of recipients increases with the expansion. Due to the expansion of the service area and the increase in the number of receivers, the business revenue of the TV operator increases accordingly. This is expected to reduce the business risk of digital broadcasting and accelerate the spread of digital TV broadcasting.

Now, as shown in the service area diagram of 32 SRQAM in FIG. 107, the same effect can be obtained when n = 1.8. By changing the shift value n, each broadcasting station changes n in accordance with local conditions and circumstances such as the distribution status of the HDTV receiver and the NTSCTV receiver, and S
D of RQAM ₁ and D ₂ of the service area 703a and 703
By setting b to the optimum condition, the receiver can obtain the maximum satisfaction and the broadcasting station can obtain the maximum number of receivers.

In this case, when n> 1.0, the above effects can be obtained. Therefore, 32SR
In the case of QAM, n is 1 <n <5. Similarly, in the case of 16 SRQAM, n becomes 1 <n <3.

In this case, in the SRQAM system in which the first and second layers are shifted as shown in FIGS. 99 and 100,
If n is 1.0 or more in 16 SRQAM, 32 SRQAM, and 64 SRQAM, the effect of the present invention can be obtained in terrestrial broadcasting. In the embodiment, the case where the video signal is transmitted has been described.
When the first data sequence is transmitted using the transmission method of the present invention, the same effect can be obtained. When used for PCM broadcasting, radio, and mobile phones, there is an effect that the service area is expanded.

Also, in the embodiment, time division multiplexing (TDM)
By providing TDM sub-channels in combination with the method and differentiating the error correction code gain of each sub-channel, the threshold of each sub-channel could be differentiated. SRQAM is a signal point code division multiplexing method (Constellat) of the present invention called “C-CDM”.
ion-Code Division Multiplex) applied to rectangle-QAM. C-CDM is a multiplexing method independent of TDM and FDM. This is a method of obtaining a sub-channel by dividing a signal point code corresponding to a code. By increasing the number of signal points, TDM or FDM
The transmission capacity expandability that cannot be obtained is obtained. This is achieved while maintaining almost complete compatibility with conventional equipment. A multiplexing technique having such excellent effects. Well, CC
Although the embodiment in which the DM and the TDM are combined is used, a similar effect of reducing the threshold can be obtained by combining with the frequency division multiplexing (FDM). For example, when used for TV broadcasting,
FIG. 108 shows a frequency distribution diagram of the TV signal.
Conventional analog broadcasting, for example, a signal of the NTSC system has a frequency distribution like a spectrum 725. The largest signal is the image carrier 722. The color carrier 723 and the audio carrier 724 are not so large. In order to avoid mutual interference, a method of dividing a digital broadcast signal into two frequencies by FDM is considered. In this case, the first carrier 726 and the second carrier 727 are arranged so as to avoid the image carrier 722 as shown in FIG.
, And the first signal 720 and the second signal 721 are sent to reduce the interference. By transmitting a low-resolution TV signal with a large output using the first signal 720 and transmitting a high-resolution signal with a small output using the second signal 721,
Hierarchical broadcasting by FDM is realized while avoiding interference.

At this time, first, the C-CDM is applied to the first signal 720.
A subchannel is added using 32 SRQAM obtained by. Next, a lower resolution component is added to the sub-channel having the lower threshold. By transmitting the normal resolution component to one of the sub-channels, the number of hierarchies is further increased, and the effect of expanding the low-resolution service area is produced. By putting important information such as audio information or synchronization information and a header of each data into the sub-channel having a low threshold value, the important information can be reliably received, thereby enabling stable reception. When a similar technique is used for the second signal 721, the number of service area layers increases. H
If the DTV has 1050 scanning lines, 775 service areas are added by C-CDM in addition to 525 scanning lines.

As described above, when the FDM and the C-CDM are combined, an effect that the service area is expanded is produced. In this case, two sub-channels are provided by FDM, but the frequency may be divided into three and three sub-channels may be provided.

Next, a method for avoiding interference by combining TDM and C-CDM will be described. As shown in FIG. 109, the analog TV signal includes a horizontal retrace unit 732 and a video signal unit 731. The fact that the signal level of the horizontal retrace unit 732 is low and that the signal is not output to the screen during this period is used. By synchronizing the digital TV signal with the analog TV signal, it is possible to send important data, for example, a synchronization signal or the like to the horizontal retrace synchronization slots 733 and 733a during the horizontal retrace section 732, or to transmit a lot of data at a high output. it can.
This has the effect that the amount of data can be increased or the output can be increased without increasing interference. Similar effects can be obtained by providing the vertical retrace synchronization slots 737 and 737a in synchronization with the periods of the vertical retrace units 735 and 735a.

FIG. 110 is a diagram showing the principle of C-CDM.
FIG. 111 shows a code allocation diagram of the 16-QAM extended version C-CDM, and FIG. 112 shows a code allocation diagram of the 32QAM extended version. As shown in FIGS. 110 and 111, 256QAM is the first, second, third and fourth layers 740a and 740.
b, 740c, and 740d, each having 4, 16, 64, and 256 segments. 256QAM signal point codeword 742d of fourth layer 740d
Is 8-bit "11111111". This is 2b
four codewords 741a, 741b, 74
1c, 741d, and the first, second, third, and fourth layers 740
a, 740b, 740c, 740d signal point area 742
a, 742b, 742c, 742d each have "11",
“11”, “11”, and “11” are assigned. Thus,
There are sub-channels of 2 bits, that is, sub-channel 1, sub-channel 2, sub-channel 3, and sub-channel 4. This is called signal point code division multiplexing. FIG. 111 shows a specific code arrangement of an extended version of 16QAM, and FIG. 112 shows an extended version of 36QAM. CC
The DM multiplexing scheme is independent. Therefore, conventional frequency division multiplexing (FDM) and time division multiplexing (TD)
By combining with M), there is an effect that the number of sub-channels can be further increased. Thus, a new multiplexing system can be realized by the C-CDM system. Although C-CDM has been described using Rectangle-QAM, other modulation schemes having signal points, for example, other forms of QAM, PSK, ASK, and the frequency domain can be regarded as signal points, and FSK can be multiplexed similarly.

(Embodiment 4) Hereinafter, a fourth embodiment of the present invention will be described with reference to the drawings.

FIG. 37 is an overall system diagram of the fourth embodiment. The fourth embodiment uses the transmission device described in the third embodiment for terrestrial broadcasting, and has almost the same configuration and operation. Example 3
The only difference between FIG. 29 and FIG. 29 is that the transmitting antenna 6a is a terrestrial transmission antenna and that each antenna 21a, 31a, 41a of each receiver is a terrestrial transmission antenna. is there. The other operations are exactly the same, and a repeated explanation will be omitted. Unlike satellite broadcasting, in the case of terrestrial broadcasting, the distance between the transmitting antenna 6a and the receiver is important. A distant receiver receives weaker radio waves, and cannot demodulate a signal simply multi-level QAM-modulated by a conventional transmitter and cannot watch a program.

However, when the transmission apparatus of the present invention is used, the first receiver 23 having the antenna 22a at a long distance as shown in FIG.
The modulated signal is received, demodulated in the 4PSK mode, and the D1 signal of the first data string is reproduced, so that an NTSC TV signal is obtained. Therefore, even if the radio wave is weak, a TV program can be viewed at a medium resolution.

Next, in the second receiver 33 in which the antenna 32a is located at a middle distance, since the arriving radio wave is sufficiently strong, the deformation 16 or 6
The second data string and the first data string can be demodulated from the 4QAM signal, and an HDTV signal can be obtained. Therefore, the same TV program is HD
You can watch on TV.

On the other hand, the third receiver 43, which is located at a short distance or has an antenna 42a of ultra-high sensitivity, has the first, second, and third data strings D1, D2 because the radio wave has sufficient strength to demodulate the modified 64QAM signal. , D3 to obtain an ultra-high resolution HDTV signal. You can watch the same TV program on a super HDTV with the same image quality as a large movie.

The method of arranging the frequencies in this case can be explained by replacing the time multiplexing arrangement with the frequency arrangement with reference to FIGS. 34, 35 and 36. As shown in FIG. 34, when frequencies are assigned to channels 1 to 6 D
In one signal, L1 of NTSC is used as the first channel, and the difference information of HDTV is used in M1 of the first channel of the signal D2.
By locating the difference information of the ultra high resolution HDTV in H1 of the first channel of the signal, it is possible to transmit NTSC, HDTV and super resolution HDTV on the same channel. Also, as shown in FIG. 35 and FIG.
If the use of the signal or the D3 signal is permitted, higher-quality HDTV and ultra-high-resolution HDTV can be broadcast.

As described above, there is an effect that three digital TV terrestrial broadcasts compatible with each other can be broadcast using the D2 and D3 signal areas of one channel or another channel. In the case of the present invention, there is an effect that a TV program of the same content on the same channel can be received in a wider area if the resolution is medium.

As a digital terrestrial broadcast, a 6 MHz band HDTV broadcast using 16QAM has been proposed.
However, since these systems are not compatible with NTSC, it is premised that a simulcast system in which the same program is transmitted through another NTSC channel is used. Also 16QAM
In the case of, the service area that can be transmitted is expected to be narrow. The use of the present invention for terrestrial broadcasting not only eliminates the need to provide a separate channel, but also has the effect that a broadcast service area is wide because a program can be viewed at a medium resolution even with a distant receiver.

FIG. 52 shows an HDT of a conventionally proposed method.
FIG. 5 is a diagram showing a reception interference area diagram for V digital terrestrial broadcasting, in which an HDTV digital broadcasting station 701 using a conventionally proposed system can receive an HDTV from a receivable area 702 and an adjacent analog broadcasting station 711 can receive. An area 712 is shown. In the overlapping portion 713 where the two overlap, it is impossible to stably receive at least HDTV due to radio wave interference of the analog broadcasting station 711.

Next, FIG. 53 is a diagram showing a reception interference area when the hierarchical broadcasting system according to the present invention is used. In the present invention, when the transmission power is the same as that of the conventional system, the high-resolution receivable area 703 of the HDTV is slightly narrower than the receivable area 702 of the above-described conventional method because the power use efficiency is low. However, there is a low-resolution receivable area 704 such as digital NTSC which is wider than the receivable area 702 of the conventional system. It consists of the above two areas. In this case, the radio wave interference from the digital broadcasting station 701 to the analog broadcasting station 711 is at the same level as the conventional system shown in FIG.

In this case, according to the present invention, the analog broadcasting station 71
There are three areas of interference from one to the digital broadcast station 701. One is a first interference area 705 that cannot receive HDTV or NTSC. The second is disturbed but N
Second jamming area 706 that can receive TSC as before jamming
Is indicated by a single oblique line. Here, the NTSC uses the first data string that can be received even if the C / N is low, so that the influence range of the interference is narrow even if the C / N decreases due to the radio wave interference of the analog station 711.

Third, a third interference area 707 in which HDTV could be received before the interference but only NTSC could be received after the interference.
Is indicated by double oblique lines.

As described above, H
The receiving area of the DTV is slightly narrower, but the receiving range including the NTSC is wider. Further, even in an area where HDTV could not be received by the conventional system due to the interference from the analog broadcasting station 711, the same program as that of the HDTV was transmitted to the NT.
Reception is possible at the SC. Thus, there is an effect that the unreceivable area of the program is greatly reduced. In this case, by slightly increasing the transmission power of the broadcasting station, the receivable area of the HDTV becomes equivalent to the conventional system. Furthermore, programs can be received with NTSCTV quality in distant areas where no programs could be viewed in the conventional system, or in areas where analog stations overlap.

Although an example using a two-layer transmission system has been described, a three-layer transmission system may be used as shown in the time allocation diagram of FIG. By separating HDTV into three levels of images of HDTV, NTSC, and low-resolution NTSC and transmitting them, the receivable area in FIG. 53 expands from two layers to three layers, and the outermost layer becomes a wide area. In the first obstruction area 705, which cannot be received at all, a program can be received with the quality of the low-resolution NTSCTV. The above is an example in which a digital broadcasting station interferes with analog broadcasting.

Next, an embodiment will be described under the condition that digital broadcasting does not interfere with analog broadcasting.
In the system using an empty channel which is currently being studied in the United States and the like, the same channel is used adjacently. For this reason, digital broadcasting that is to be broadcast later must not interfere with existing analog broadcasting. Therefore, it is necessary to lower the transmission level of the digital broadcast as compared with the case where the transmission is performed under the conditions shown in FIG. In this case, in the case of the conventional 16QAM or 4ASK modulation, the receivable area 708 of the HDTV becomes very small because the non-receivable area 713 indicated by double oblique lines is large as shown in the interference state diagram of FIG. . The service area is narrowed, and the number of recipients is reduced correspondingly, so the number of sponsors is reduced. Therefore, it is expected that the broadcasting business is hardly economically established in the conventional system.

Next, FIG. 55 shows a case where the broadcast system of the present invention is used. The HDTV high resolution receivable area 703 is
It is slightly smaller than the receivable area 708 of the conventional method. However, a lower resolution receivable area 704 such as NTSC is obtained in a wider range than the conventional method. The part indicated by a single diagonal line cannot receive the same program at the HDTV level, but the NTSC
Indicates the area that can be received at the level. Among them, the first interference area 705 receives interference from the analog broadcasting station 711, and neither HDTV nor NTSC can be received.

As described above, in the case of the same radio wave intensity, in the hierarchical broadcasting of the present invention, the receivable area of the HDTV quality is slightly narrowed, but the area where the same program can be received in the NTSCTV quality increases. This has the effect of increasing the service area of the broadcasting station. The effect is that the program can be provided to more recipients. The broadcasting business of HDTV / NTSCTV can be established more economically and stably.
When the ratio of digital broadcasting receivers increases in the future, the interference rules for analog broadcasting are relaxed, so that the radio wave intensity can be increased. At this point, the service area of the HDTV can be enlarged. In this case, by adjusting the interval between the signal points of the first data string and the second data string, FIG.
The digital HDTVINTSC receivable area and the digital NTSC receivable area indicated by 5 can be adjusted. In this case, by transmitting information of this interval to the first data string as described above, reception can be performed more stably.

FIG. 56 is a diagram showing the state of interference when switching to digital broadcasting in the future. In this case, unlike FIG. 52, the adjacent station is a digital broadcasting station 701a that performs digital broadcasting. Since the transmission power can be increased, the high-resolution receivable area 703 such as HDTV can be expanded to a receivable area 702 equivalent to analog TV broadcasting.

A conflict area 71 between both receivable areas
In No. 4, the program cannot be reproduced in the HDTV quality with a normal directional antenna because of mutual interference.
It can be received with the quality of TSCTV. When an antenna with a very high directivity is used, a program of a broadcasting station in the directivity direction of the antenna can be received with HDTV quality. The low-resolution receivable area 704 is wider than the standard receivable area 702 of analog TV broadcasting, and the competing areas 715 and 716 of the low-resolution receivable area 704a of an adjacent broadcast station are broadcast stations in the direction of the antenna directivity. Is NTSCTV
You can play with the quality of.

By the way, the regulation conditions will be further relaxed in the full-scale spread of digital broadcasting in the future, and the hierarchical broadcasting of the present invention will enable HDTV broadcasting over a wide service area. Even at this point, by adopting the hierarchical broadcasting system of the present invention, the H
NTSCT is ensured even in distant areas and competing areas that cannot be received by the conventional method while ensuring the DTV reception range.
Since the program can be received with the quality of V, there is an effect that the defective portion of the service area is greatly reduced.

(Embodiment 5) Embodiment 5 is an embodiment in which the present invention is used for amplitude modulation, that is, the ASK method. FIG. 57 shows a four-valued ASK signal signal point arrangement diagram of Embodiment 5. There are two signal points 721, 722, 723, 724. In the case of four values, 2-bit data can be transmitted in one cycle.
Signal points 721, 722, 723, 724 are set to, for example, 00,
01, 10, and 11.

In order to perform hierarchical transmission according to the present invention, as shown in FIG. 58, signal points 721 and 722 are treated as one group, that is, a first signal point group 725,
23 and 724 are defined as another group, a second signal point group 726. Then, the interval between the two signal point groups is made wider than the interval between the equally spaced signal points. That is, the signal points 721 and 72
The interval of the signal points 723 and 724 when the second distance is L good for the same L, but the interval L _o of the signal point 722 and signal points 723
Is set to be larger than L.

That is, L _o > L is set. This is a feature of the hierarchical transmission system of the present invention. However it may become temporarily or permanently L = L _o by the conditions and settings, depending on the design of the system.

As shown in FIG. 59 (a), _one bit data of the first data string D1 can be made to correspond to two signal point groups. For example, the first signal point group 725 is set to 0, the second
If the signal point group 726 of the first data string is defined as 1,
Bit signals can be defined. Next, 1 of the second data string D ₂
A bit signal is made to correspond to two signal point groups in each signal group. For example, as shown in FIG.
If 23 is set to D ₂ = 0 and the signal points 722 and 724 are set to D ₂ = 1, the data of the second data string D ₂ can be defined. Also in this case, it is 2 bits / symbol.

By arranging signal points in this way,
The ASK scheme enables the hierarchical transmission of the present invention. When the signal-to-noise ratio, that is, the C / N value is sufficiently high, the hierarchical transmission system is no different from the conventional evenly spaced signal point method. But,
When the C / N value is low, the second method can be used by using the present invention even under the condition that no data can be reproduced by the conventional method.
Data stream D ₂ will not be reproduced, but the first data stream D ₁ can be reproduced. Explaining this, the state where the C / N ratio has deteriorated can be shown in FIG. That is, the signal points reproduced by the receiver are dispersed signal point areas 721a due to noise and transmission distortion.
Gaussian distribution is performed over a wide range of 722a, 723a, and 724a. In such a case, it is difficult to distinguish between the signal points 721 and 722 and the signal points 723 and 724. That second error rate of the data stream D ₂ is very high. However, as is apparent from the figure, the signal points 721, 7
It is easy to distinguish the 22 groups from the signal points 723 and 724 groups. That is, the first signal point group 725 and the second
Can be distinguished from the signal point group 726 of FIG. Therefore, the first data stream D ₁ will be playable on a low error rate.

In this way, data strings D ₁ and D _{2 of} two layers can be transmitted and received. Thus both in good condition and the region of C / N of the transmission system of the first data stream D ₁ and the second column D ₂ is C /
The bad and regions with N there is an effect that it is multi-level signal transmission in which only the first data stream D ₁ can be reproduced.

FIG. 61 is a block diagram of a transmitter 741. The input section 742 includes a first data string input section 743 and a second data string input section 744. The carrier wave from the carrier generator 64 is amplitude-modulated in the multiplier 746 by an input signal obtained by combining the signal from the input unit 742 in the processing unit 745 and further band-limited by the filter 747 to become an ASK signal such as a VSB signal from the output unit 748. Is output.

Here, the output waveform after passing through the filter will be described. FIG. 62A is a frequency distribution diagram of the ASK modulation signal. As shown, there are sidebands on both sides of the carrier. This signal is used to remove one sideband while leaving a small carrier component like a transmission signal 749 in the band-pass filter (FIG. 62B) of the filter 747. This is called VSB signal, but when the f ₀ and modulation frequency band, since that can be transmitted in a frequency band of about f _0/2, it is known that spectrum efficiency is good. The ASK signal shown in FIG. 60 is originally 2 bits / symbol, but if the VSB method is used, an information amount corresponding to 4 bits / symbol of 16QAM can be transmitted in the same frequency band.

Next, the receiver 75 shown in the block diagram of FIG.
1, the signal received by the terrestrial antenna 32a is
2, a variable oscillator 7 that can be varied by channel selection
The signal from the signal 54 is mixed in the mixer 753 and converted to a low intermediate frequency. Next, it is detected by the detector 755, becomes a baseband signal by the LPF 756, and the first data sequence D ₁ and the second data sequence D ₂ are reproduced by the discriminator / reproducer 757. The first data sequence output unit 758 and the second data sequence output unit 759.

Next, a case where a TV signal is transmitted using the transmitter and the receiver will be described. FIG. 64 shows a video signal transmitter 774.
It is a block diagram of. High resolution TV signal such as HDTV signal is input to the input unit 403 of the first image encoder 401, a separating circuit 404 of the video such as sub-band _{filter, H L V L, H L} V H, H H V L, H It is separated into high-frequency TV signal and a low TV signal such as _H H _H. Since this content has been described in the third embodiment with reference to FIG. 30, detailed description will be omitted. The separated TV signal is encoded in the compression section 405 using a technique such as DPCMDCT variable length encoding used in MPEG or the like. The motion compensation is processed in the input unit 403. The four compressed image data are combined by a combiner 771 into two data, a first data string D ₁ and a second data string D ₂ .
Data strings. In this case, the _{HL VL} signal, that is, the low-frequency image signal is included in the first data string. First data string input section 743 and second data string input section 744 of transmitter 741
And is subjected to amplitude modulation to become an ASK signal such as VSB, which is broadcast from a ground antenna.

FIG. 65 is a block diagram of the entire TV receiver for digital TV broadcasting. The broadcast signal received by the terrestrial antenna 32a is input to the input unit 752 of the receiver 751 in the TV receiver 781, and the signal of an arbitrary channel desired by the receiver is selected and demodulated by the detection and demodulation unit 760. The first data string D ₁ and the second data string D ₂ are reproduced and the first
Output from the data string output unit 758 and the second data string output unit 759. Detailed explanations are omitted because they overlap. The D ₁ and D ₂ signals are input to the separation unit 776. The D ₁ signal is supplied to the separator 77
7, the H _L V _L compressed component is input to the first input unit 521. The other is combined with the D ₂ signal by the combiner 778 and input to the second input unit 531. The H _L V _L compressed signal input to the first input unit 521 in the second image decoder is
Sent to H _L V _L signal is expanded image combining unit 548 and the screen ratio changing circuit 779 by first extending portion 523. Original T
If V signal is an HDTV signal, H _L V _L signal is wide N
If the original signal is an NTSC signal, M
Low resolution TV lower in quality than NTSC such as PEG1
Signal.

[0206] In order to have set the original video signal HDTV signal and in this description, T of H _L V _L signal is wide NTSC
V signal. If the screen aspect ratio of the TV is 16: 9, it is output as the video output 426 via the output unit 780 with the screen ratio of 16: 9. If the screen aspect ratio of the TV is 4: 3, the screen aspect ratio changing circuit 779 changes the screen aspect ratio from 16: 9 to 4: 3 in the letterbox format or the side panel format, and outputs it via the output unit 780. Output as a video output 425.

On the other hand, the second data string D ₂ from the second data string output unit 759 is combined with the signal of the separator 777 in the combiner 778 of the separator 776, and the combined signal is supplied to the second input unit 531 of the second image decoder. Input, and H
_{L V H, H H V L} , H H V H are separated into compressed signals of each second
Decompression unit 535, the third extension portion 536, is sent to the fourth extension portion is extended original _{H L V H, H H V} L, the _H H V _H signal. The H _L V _L signal is applied to these signals, the image synthesizing unit 54
8 and synthesized into one HDTV signal, output from the output unit 546, and output via the output unit 780.
It is output as a V video signal 427.

This output section 780 is the second data string output section 7
The error rate detection unit 782 detects the error rate of the 59 second data string.
In case the detected error rate is high to automatically output the low resolution video signal H _L V _L signal.

[0209] As described above, transmission and reception of a hierarchical broadcast can be performed. If the transmission conditions are good, for example, for a broadcast with a TV transmission antenna close to the broadcast, both the first data sequence and the second data sequence can be reproduced, so that the program can be received with HDTV quality. The relative distance is long broadcast transmitting antenna, and reproducing the first data stream, and outputs a low resolution TV signal from the V _L H _L signal. This allows HD
There is an effect that the same program can be received in a wider area with the quality of TV or the quality of NTSCTV.

Also, if the function of the receiver 751 is reduced only to the first data string output unit 768 as shown in the block diagram of the TV receiver in FIG. 66, the receiver does not need to handle the second data string and the HDTV signal. The configuration can be greatly simplified. As the image decoder, the first image decoder 421 described in (FIG. 31) may be used. In this case, NTSCT
An image of V quality is obtained. Although the program cannot be received at the HDTV quality, the cost of the receiver is greatly reduced. Therefore, it may be widely spread. In this system, many receiving systems with conventional TV displays are added as adapters without change, so that digital T
There is an effect that V broadcast can be received.

With the configuration as shown in FIG. 67, a receiver having the functions of a satellite broadcast receiver for demodulating a PSK signal and a terrestrial broadcast receiver for demodulating an ASK signal can be easily configured. In this case, the PSK signal received from the satellite antenna 32 is mixed with the signal from the oscillator 787 in the mixer 786,
The signal is converted into a low frequency signal, and is input to the input unit 34 of the TV receiver 781, and is input to the mixer 753 described with reference to FIG. Data streams D ₁ and D _{2 of} the PSK or QAM signal converted to a lower frequency of a specific channel of the satellite TV broadcast are demodulated by the demodulation unit 35, and the image signal is transmitted by the second image encoder 422 via the separation unit 788. And output from the output unit 780. On the other hand, digital terrestrial broadcasting and analog broadcasting received by the terrestrial antenna 32a are input to the input unit 752, and a specific channel is selected by the mixer 753 in the same process as described with reference to FIG. It becomes a baseband signal of only the band. The signal enters the mixer 753 for analog satellite TV broadcasting and is demodulated. In the case of digital broadcasting, the data streams D ₁ and D ₂ are reproduced by the discriminator / reproducer 757 and the second image decoder 42
2 reproduces and outputs a video signal. When receiving terrestrial and satellite analog TV broadcasts, the video demodulator 7
The analog TV signal demodulated by 88 is output to the output unit 7.
80 is output. With the configuration of FIG.
3 can be shared by satellite broadcasting and terrestrial broadcasting. Also, the second image decoder 422 can be shared. In digital terrestrial broadcasting, A
When the SK signal is used, a detector 755 and a receiving circuit such as an LPF 756, which are the same as those used in conventional analog broadcasting, can be used for AM demodulation. As described above, the configuration shown in FIG. 67 has an effect that the receiving circuit is widely used and the number of circuits is reduced.

Further, in this embodiment, the quaternary ASK signals are divided into two groups, and _one- bit hierarchical transmission of each of two layers D ₁ and D ₂ is performed. However, as shown in FIG.
When a signal is used, hierarchical transmission of one bit of each of three layers D ₁ , D ₂ , and D ₃ can be performed. D ₃ signal signal point in FIG. 68 signal points 721a and 721b, 722a and 722
b, 723a and 723b, and 724a and 724b, ie, 1 bit. Next, the signal point of D ₂ is a signal point group 72.
1 and 722, binary 1 bit of signal point group 723 and 724
It is. 2 D ₃ data with large signal point groups 725 726
The value is 1 bit. In this case, the four signal points 721, 722, 723, and 724 in FIG.
1a and 721b, 722a and 722b, 723a and 72
3b, 724a and 724b, and the distance between the groups is increased to enable three-layer hierarchical transmission.

Using this three-layer hierarchical transmission system,
The video transmission of the layer is described in the third and third embodiments, and the detailed description of the operation is omitted.

In the third embodiment, the image encoder 401 as shown in FIG. 30 has been described. However, the block diagram of FIG. 30 can be rewritten as shown in FIG. The description is omitted because the contents are completely the same. As described above, the image encoder 401 includes the video separation circuit 40 such as a sub-band filter.
4, two 404a. Assuming that these are the separating unit 794, it is shown in the block diagram of the separating unit in FIG. As described above, the number of circuits can be reduced by passing a signal twice through one separation circuit in a time-division manner. To explain this, the image signal is time-base compression circuit 795 of the HDTV and super HDTV from the input unit 403 in the first cycle, the separating circuit 404 is compressed time _{axis, H H V H -H, H} H V _L -H, _{H L} V H -
H and H _L V _L +1. in this case,
Switch 765,765a, 765b, 765c is in the first position, the compression unit _{405, H H V H -H,} H H V L -
H, outputs three signals of _{H L} V H -H. But H _L
V _L -H signal is inputted from the output 1 of the switch 765c to the input 2 of the time axis adjusting circuit 795, is sent to separation circuit 404 separates the processing in the free time of the time division processing second cycle, that H _H V _{H, H H V L, H L V} H, is divided into four components H _L V _L outputs. In the second cycle, switch 76
Since 5, 765a, 765b, and 765c change to the position of the output 2, the four components are sent to the compression unit 405. By performing the time-division processing with the configuration of FIG. 70 in this manner, there is an effect that the number of separation circuits can be reduced.

Next, when such a three-layer hierarchical image transmission is performed, an image decoder as described in the block diagram of FIG. 33 of the third embodiment is required on the receiver side. When this is rewritten, a block diagram as shown in FIG. 71 is obtained. There are two combiners 566 having the same configuration but different processing capabilities.

This has the structure shown in FIG.
In the same manner as in the case of the separation circuit of FIG. Referring to FIG. 72, five switches, 765a,
First, at timing 1, the switches 765, 765a, 765b, 765b, 765c, 765d
The input of 765c switches to 1. Then, first extending portion 522, a second extending portion 522a, the third extension portion 522b, each H _L V _L from the fourth extension portions _{522c, H L V H, H} H V L, H
_{The H} V _H signal is input to the corresponding input unit of the synthesizer 556 via the switch, and is subjected to a synthesis process to form one video signal. This video signal is sent to switch 765d and output 1
And output again to the input 2 of the switch 765c.
This video signal is originally a signal of H _L V _L -H components obtained by dividing a high resolution video signal. At the next timing 2, the switches 765, 765a, 765b, and 765c are switched to the input 2. Thus, this time H _H V _H −H, H _{H
V L -H, H L V H} -H , and H _L V _L -H signal combiner 5
The video signal is sent to a video signal 56, where the video signal is synthesized and one video signal is obtained. This video signal is output from the output unit 554 from the output 2 of the switch 765d.

As described above, when three-layer hierarchical broadcasting is received, there is an effect that two synthesizers are reduced to one by time division processing.

[0218] Now, this method, first, in the timing _{1 H H V H, H H} V L, H L V H, to enter the H _L V _L signal, H
The _L V _L -H signal is synthesized. After that, at timing 2 different from timing 1, H _H V _H −H, H _H V _L −
_H, H _L V H -H and to enter the above H _L V _L -H signal takes the steps of obtaining a final video signal. Therefore,
It is necessary to shift the timing of the two groups of signals.

If the order of the timings of the components of the input signal is originally different or overlapping, the switches 765, 765a, and 766 are used to separate them in time.
It is necessary to provide a memory in 5b and 765c and accumulate them, and adjust the time axis. However, the transmission signal of the transmitter is
As described above, by transmitting the signals in a time-separated manner at timing 1 and timing 2, a time axis adjusting circuit is not required on the receiver side. Therefore, there is an effect that the configuration of the receiver is simplified.

[0220] D1 time layout of FIG. 73 shows a first data stream D1 of the transmission signal, H _L V _L by the D-channel for the duration of the timing _{1, H L V H, H} H V L, H H V Send _H signal,
H _L V _H -H at D2 channel during the timing 2, H
_H V _L -H, shows the time arrangement of signals when sending the _{H H} V _H -H. By transmitting the transmission signals in a temporally separated manner in this manner, there is an effect that the circuit configuration of the econcoder of the receiver is eliminated.

Next, the number of expansion units of the receiver is large. A method for reducing these numbers will be described. FIG. 74 (b) shows a time allocation diagram of transmission signal data 810, 810a, 810b, 810c. In this figure, different data 811, 810a, 811b, 811c are transmitted between data.
Then, the target transmission data is intermittently transmitted. Then, the second image encoder 422 shown in the block diagram of FIG.
The data is sequentially input to the extension unit 503 via the switch 21 and the switch 812. For example, after the input of the data 810 is completed, the decompression process is performed during the time of the separate data 811. After the processing of the data 810 is completed, the next data 810a is input. In this way, one decompressor 503 can be shared in a time-division manner in the same manner as in the case of the synthesizer. Thus, the total number of extension portions can be reduced.

FIG. 75 is a time allocation diagram when HDTV is transmitted. For example, NTS of the first channel of a broadcast program
Assuming that the _{HL VL} signal corresponding to the C component is _{HL VL} (1),
This is time-arranged at the position of the data 821 indicated by the bold line of the D1 signal. _{H L V H, H H V} L, H H V H signal D2 signal of the data 82 corresponding to the HDTV additional components of the first channel
1a, 821b, and 821c. Then, separate data 822, 822a, 822b, and 822, which are information of another TV program, are placed between all the data of the first channel.
Since c exists, the extension processing of the extension unit can be performed during this period. In this way, all the components can be processed in one extension unit. This method can be applied when the processing of the decompressor is fast.

A similar effect can be obtained by arranging data 821, 821a, 821b and 821c in D1 signal as shown in FIG. This is effective when transmission / reception is performed using transmission without a layer such as normal 4PSK or 4ASK.

FIG. 77 shows, for example, NTSC, HDTV and high-resolution HDTV, or low-resolution NTSC and NTSC.
FIG. 2 is a time allocation diagram when hierarchical broadcasting is performed by using a two-layer hierarchical transmission system such as a three-layer video such as HDTV. For example, when broadcasting low-resolution NTSC, NTSC, and HDTV three-layer video, the D1 signal includes low-resolution NTSC.
H _L V _L signal corresponding to the signal is placed in the data 821. Further, the separation signal _{NTSC H L V H, H H} V L,
The signal of each component of H _H V _H is represented by data 821a, 821b, 8
It is arranged at the position 21c. HDTV is a separation signal _{H L V H -H, H H} V L -H, H H V H -H signal are arranged data 823,823A, to 823b.

Here, a logical hierarchical transmission by differentiating the error correction capability described in the second embodiment is added.
H _L D _L specifically uses a D _1-1 channel in the D ₁ signal. D _1-1 channel employs a high error correction method having greatly in correction capability than D _1-2 channel, as described in Example 2. Since D _1-1 channel redundancy than the D _1-2 channel is less high, but the error rate after regeneration, other data 821a, 821b, from 821c C /
Reproduction can be performed even under conditions where the N value is low. For this reason, even in a case where reception conditions are poor, such as in an area far from the antenna or in a car, a program can be reproduced with low-resolution NTSCTV quality. When viewed in terms of error rate as described in Example 2, other data 821a data 821 in the D _1-1 channel in the D ₁ signal on the D _1-2 channel, 821b, reception interference from 821c Strong, differentiated and have different logical hierarchies. As described in the second embodiment, the layers D ₁ and D ₂ can be said to be physical layers, and the hierarchical structure obtained by differentiating the distance between error correction codes can be said to be a logical hierarchical structure.

The demodulation of the D ₂ signal requires a physically higher C / N value than the D ₁ signal. Therefore, C
/ The lowest reception condition of N values, i.e. H _L V _L signal, the low resolution NTSC signal is reproduced. Then, C / N value added in the next lower receiving condition _{H L V H, H H V} L, H H V H are reproduced, NTSC signal can be reproduced. In addition to the H _L V _L is high reception conditions of C / N values _{H L V H -H, H H} V L
-H, HDTV signals for also played _H H V _H -H is played. Thus, broadcasting of three layers can be performed. By using this method, the receivable area described with reference to FIG. 53 is expanded from two layers to three layers as shown in the reception interference area diagram of FIG. 90, and the program receivable area is further expanded.

Here, FIG. 78 is a block diagram of the third image decoder in the case of the time arrangement shown in FIG. Basically Figure 7
The block diagram of FIG. 74 is obtained by adding the configuration of the block diagram of FIG. 74A to the configuration in which the third input unit 551 of the D3 signal is omitted from the block diagram of FIG.

In operation, at timing 1, the D1 signal is input from the input unit 521, and the D2 signal is input from the input unit 530. Since the components such as H _L V _H are temporally separated, they are sequentially and independently sent to the expansion unit 503 by the switch 812. This sequence will be described with reference to the time allocation diagram of FIG. First, the _{HL VL} compressed signal of the first channel enters the decompression unit 503 and is decompressed. Then the first channel of _{H L V H, H H V} L, is _H H V _H are expanded processed, via the switch 812a is input to a predetermined input of the combiner 556 is combining processing, first, H _L The _VL- H signal is synthesized. This signal is input from the output 1 of the switch 765a to the input 2 of a switch 765, is input to the H _L V _L input of the combiner 556.

[0229] In the next timing 2, the D2 signal, as shown in the time arrangement of FIG _{77 H L V H -H, H} H V L -
_H, H H V H -H signal is inputted is extended by extension 503, the signal through the switch 812a is combiner 556
, And are subjected to a synthesis process to output an HDTV signal. The HDTV signal is output from the output 2 of the switch 765a via the output unit 521. As described above, transmission by the time arrangement shown in FIG. 77 has an effect of greatly reducing the number of decompressing units and the number of combiners of the receiver. Incidentally, FIG. 77 shows D1,
Although the two stages of the D2 signal are used, the use of the above-described D3 signal enables high-definition HDTV and TV broadcasting of four layers.

FIG. 79 is a time allocation diagram of a hierarchical broadcasting for broadcasting three hierarchical images using three physical layers D1, D2 and D3. As is clear from the figure, the components of the same TV channel are arranged so as not to overlap in time.
FIG. 80 shows a receiver in which the third input unit 521a is added to the receiver described in the block diagram of FIG. Broadcasting according to the time arrangement in FIG. 79 has the effect that the receiver can be configured with a simple configuration as shown in the block diagram in FIG.

The operation is almost the same as the time allocation diagram of FIG. 77 and the block diagram of FIG. 78. Therefore, description is omitted.
Also, as shown in the time allocation diagram of FIG. 81, all signals can be time-multiplexed to the D1 signal. In this case, the data 821
Data 821a and 8
The error correction capability is higher than 12b and 821c. For this reason, the hierarchy is higher than other data. As described above, physically one layer but logically two.
Hierarchical transmission of layers. Further, another data of another program channel 2 is included between the data of the program channel 1. Therefore, serial processing can be performed on the receiver side, and the same effect as that in the time allocation diagram of FIG. 79 can be obtained.

In the case of the time allocation diagram shown in FIG. 81, the transmission layer has a logical hierarchy. Since the error rate of the data is reduced, physical hierarchical transmission can be performed. In this case, there are three physical layers.

FIG. 82 is a diagram similar to that of FIG.
Image decoder 4 for transmitting only data string D1 signal
The block diagram of FIG. 23 has a simpler configuration than the image decoder shown in the block diagram of FIG. The operation is shown in FIG.
The description is omitted because it is the same as the image decoder described above.

As described above, when a transmission signal as shown in the time allocation diagram of FIG. 81 is transmitted, there is an effect that the number of decompressor 503 synthesizers 556 can be greatly reduced as shown in the block diagram of FIG. In addition, since the four components are temporally separated and input, the combiner 556, that is, the image combining unit 5 in FIG.
By changing the connection of the internal 48 circuit blocks according to the input image components, some blocks can be shared in a time-sharing manner and the circuit can be omitted.

As described above, there is an effect that the receiver can be configured with a simple configuration. In the fifth embodiment, the AS
Although the operation has been described using K modulation, many of the methods described in the fifth embodiment use the PSK or QA described in the first, second, and third embodiments.
It can also be used for M modulation.

The embodiments described above can also be used for FSK modulation. For example, as shown in FIG. 83, f1, f2, f3, f4
When performing multi-level FSK modulation, hierarchical transmission can be performed by performing grouping as shown in the signal point arrangement diagram of FIG. 58 of the fifth embodiment and separating signal point positions of each group.

In FIG. 83, a frequency group 841 of frequencies f1 and f2 is defined as D1 = 0, and a frequency group 842 of frequencies f3 and f4 is defined as D1 = 1. And f1, f3
Is defined as D2 = 0, f2 and f4 are defined as D2 = 1, as shown in the figure, 1-bit each of D1 and D2, that is, 2-bit hierarchical transmission is possible. For example, when C / N is high, t = t
3, D1 = 0 and D2 = 1 can be reproduced, and at t = t4, D1 = 1 and D2 = 0 can be reproduced. Next, when C / N is low, only D1 = 0 can be reproduced at t = t3, and only D = 1 can be reproduced at t = t4. Thus, hierarchical transmission of FSK can be performed. The hierarchical transmission method of FSK can be used for the hierarchical broadcasting of the video signal described in the third, fourth, and fifth embodiments.

Further, the magnetic recording / reproducing apparatus shown in the block diagram of FIG. 84 can use the fifth embodiment of the present invention. In the fifth embodiment, magnetic recording and reproduction can be performed because of ASK.

Referring to FIG. 84, the magnetic recording / reproducing device 8
51, a video signal inputted separated and compressed by the image encoder 401, a low frequency video signal, such as H _L V _L components in a first data stream input unit 743 in the input unit 742, a second data stream input unit 744 enter the high-frequency video signal including _H H V _H components, etc., and input to the modulation unit 749 in the modem 852. The operation so far is almost the same as the transmitter of the fifth embodiment shown in FIG. The modulated signal is recorded on a magnetic tape 855 by a recording / reproducing circuit 853 and a magnetic head 854. This recording method can be a physical hierarchical recording by modifying the conventional digital multi-level recording, or a hierarchical recording by phase modulation or phase amplitude modulation as in the first and third embodiments. Hierarchical recording with multiple tracks on a magnetic tape is also possible. Hierarchical recording by changing the data transmission rate is also possible. In addition, logical hierarchical recording by differentiating data by changing the error correction capability is also possible.

Next, at the time of reproduction, the magnetic tape 855 sends a reproduction signal to the modem 852 by the magnetic head 854 and the magnetic reproduction circuit 853. The following operation is substantially the same as in the first, third, and fourth embodiments. The first data string D is output by the demodulation unit 760.
1 and the second data string D2,
Outputs a video signal. In this case, since the hierarchical recording is performed, when the C / N is high, a high-resolution TV signal such as an HDTV can be reproduced. On the other hand, when the C / N is low or when reproduction is performed by a magnetic reproducing device having a low function,
A TV signal or a low-resolution NTSCTV signal is output.

As described above, in the magnetic reproducing apparatus using the present invention, even when the C / N ratio is low or the error rate is high, it is possible to reproduce the video of the same content with low resolution or low image quality. can get.

(Embodiment 6) In Embodiment 6, the present invention is used for four-layer video hierarchy transmission. By combining the four-layer transmission scheme and the four-layer video data structure described in the second embodiment, the four-layer transmission scheme is used as shown in the reception block diagram in FIG.
A layer reception area is created. As shown in the figure, a first reception area 890a is formed on the innermost side, and a second reception area 890b, a third reception area 890c, and a fourth reception area 890d are formed outside the first reception area 890a.
A method for realizing the four layers will be described.

To realize four layers, there are a four-layer physical layer by modulation and a four-layer logical layer by differentiation of error correction capability. C / N is required. The latter is based on the premise that demodulation is possible, so that the C / N difference between layers cannot be made large. It is realistic to perform four-layer transmission using two physical layers and two logical layers. Then
First, a method of separating a video signal into four layers will be described.

FIG. 93 is a block diagram of the separation circuit 3. The separation circuit 3 comprises a video separation circuit 895 and four compression circuits. The basic configuration inside the separation circuits 404a, 404b, and 404c is similar to that of the first image encoder 40 shown in FIG.
1 is the same as the block diagram of the separation circuit 404 in FIG. The isolation circuit 404a like the video signal low frequency component H _L V _L and highband components _H H V _H and the intermediate component _{H H} V _L, 4 of H _L V _H
Split into two signals. In this case, H _L V _L is the resolution becomes half of the original video signal.

The input video signal is supplied to the video separation circuit 40.
4a divides the high-frequency component and the low-frequency component into two. Since the image is divided in the horizontal and vertical directions, four components are output. The dividing point of the high band and the low band is at the middle point in this embodiment. Therefore, when the input signal is a 1000 vertical HDTV signal, H
_L V _L signal of 500 vertical, a horizontal resolution of a half TV signal.

The H _L V _L signal of the low frequency component is separated by the separation circuit 404c.
As a result, the horizontal and vertical frequency components are further divided into two. Therefore H _L V _L outputs, for example 250 lines vertically, the horizontal resolution is 1/4. When this is defined as an LL signal, the LL component is compressed by the compression unit 405a and output as a _D1-1 signal.

On the other hand, the three components of the high frequency components of H _L V _L are combined into one LH signal by the combiner 772c,
5b, and is output as a _D1-2 signal. In this case, three compression units may be provided between the separation circuit 404c and the synthesizer 772c.

[0248] of the high frequency component _{H H V H, H L V} H, 3 components of _H H V _L becomes a _H H V _H -H signal by combiner 772a. When the compression signal is 1000 in both the vertical and horizontal directions, this signal has 500 to 1000 components in the horizontal and vertical directions. Then, the light is separated into four components by a separation circuit 404b.

[0249] Thus the horizontal as H _L V _L outputs, 500 to 750 pieces of components in the vertical direction are separated. This is called an HH signal. Then _{H H V H, H L V} H, 3 components of _H H V _L 7
It has 50 to 1000 components, is synthesized by a synthesizer 772b, becomes an HH signal, is compressed by a compression unit 405d, and has
Output as _2-2 signal. On the other hand, the HL signal is output as a _D2-1 signal. Accordingly LL, i.e. D _1-1 signal, for example 0 This 250 present the following ingredients, LH clogging D _1-2 signal is 250 or more 500 or less of the frequency component HL clogging D
_{The 2-1} signal has a frequency component of 500 or more and 750 or less, and the HH, that is, the _D2-2 signal has a frequency component of 750 or more and 1000 or less. This separation circuit 3 has an effect that a hierarchical data structure can be formed. By using the separation circuit 3 of FIG. 93 to replace the part of the separation circuit 3 in the transmitter 1 of FIG. 87 described in the second embodiment, four-layer hierarchical transmission can be performed.

By combining the hierarchical data structure and the hierarchical transmission in this way, it is possible to realize an image transmission in which the image quality gradually deteriorates as the C / N deteriorates. This has the great effect of expanding the service area in broadcasting.
Next, the receiver for demodulating and reproducing this signal has the same configuration and operation as the second receiver in FIG. 88 described in the second embodiment. Therefore, the entire operation is omitted. However, the configuration of the synthesizing unit 37 differs from that of data transmission because it handles video signals. Here, the combining unit 37
Will be described in detail.

As described in the second embodiment with reference to the block diagram of the receiver shown in FIG. 88, the received signal is demodulated and error-corrected, and D _1-1 , D _1-2 , D _2-1 , D _{2-1 2-2-4}
And is input to the synthesizing unit 37.

FIG. 94 is a block diagram of the synthesizing unit 33. The input D _1-1 , D _1-2 , D _2-1 , and D _2-2 signals are expanded in expansion units 523a, 523b, 523c, and 523d, and LL and L described in the separation circuit of FIG.
H, HL, and HH signals. When the horizontal and vertical bands of the original video signal are set to 1, LL is Ｌ, and L
L + LH is 1/2, LL + LH + HL is 3/4, LL +
LH + HL + HH is one band. The LH signal is separated by the separator 531a, and the L
Is combined with the L signal is input to the H _L V _L terminal of the image synthesizing unit 548c. The description of the example of the image synthesizing unit 531a has been described with reference to the image decoder 527 in FIG.
On the other hand, the HH signal is separated by the separator 531b and input to the image combining unit 548b. The HL signal is output from the image synthesizing unit 5.
Is combined with HH signal at 48b, separated by the separator 531c becomes _H H V _H -H signal, the image combining unit 548
In step c, the signal is synthesized with the synthesized signal of LH and LL, and is output as a video signal from the synthesizing unit 33. And the second in FIG.
The signal is output as a TV signal at the output unit 36 of the receiver. In this case, the original signal is 1050 vertical, about 1000 HDT
If it is a V signal, TV signals of four image quality are received under the four reception conditions shown in the reception interference diagram of FIG.

The picture quality of the TV signal will be described in detail. Figure 91
FIG. 86 is combined with FIG. 86 to form a transmission hierarchical structure diagram of FIG. Thus, the reception area 86 is improved with the improvement of the C / N.
D _1-1 in 2d, 862c, 862b and 862a,
Hierarchical channels that can be successively reproduced such as D _1-2 , D _2-1 and D _2-2 are added to increase the data amount.

In the case of hierarchical transmission of a video signal, as shown in the transmission hierarchical structure diagram of FIG. 95, LL, LH, H
The hierarchical channels of the L and HH signals are reproduced. Therefore, as the distance from the transmitting antenna decreases, the image quality improves. LL signal when L = Ld, L when L = Lc
L + LH signal, when L = Lb, LL + LH + HL signal, L
When = La, the LL + LH + HL + HH signal is reproduced.
Therefore, if the band of the original signal is 1, １ ／, 、 ３, 3
/ 4, 1 band image quality can be obtained in each receiving area. If the original signal is an HDTV with 1000 vertical scanning lines, 250
, 500, 750, and 1000 TV signals are obtained. In this way, hierarchical video transmission in which image quality gradually deteriorates becomes possible. FIG. 96 shows a conventional digital HDTV.
It is a reception interference figure in the case of a broadcast. As is apparent from the figure, in the conventional system, the reproduction of the TV signal becomes completely impossible when CN is equal to or lower than V _O. Therefore, even within the service area distance R, reception is not possible as shown by the mark x in a competing area with another station, a building shadow, or the like. FIG. 97 is a reception state diagram of the HDTV hierarchical broadcast using the present invention. As shown in FIG. 97, C / N = a at distance La, C / N = b at Lb, and C / N = C at Lc.
C / N = d for c and Ld, 250 for each receiving area
Image quality of 500, 750, and 1000 lines can be obtained. C / N is inferior even within the distance La, and there are areas where reproduction cannot be performed with the HDTV image quality itself. However, even in that case, reproduction can be performed even if the image quality is deteriorated. For example, at the point B of the building, there are 750 trains, and at the point D on the train, 25
0 points, 750 points at the F point where the ghost is received, 250 points at the G point in the car, and 250 points at the L point, which is a competitive area with other stations, can be reproduced. As described above, by using the hierarchical transmission according to the present invention, it is possible to receive even in an area where reception and reproduction cannot be performed by the conventionally proposed method, and there is a remarkable effect that the service area of the TV station is greatly expanded. . Also, broadcast program D of the same program as the analog broadcasting in the area at D _1-1 channel, as shown in hierarchical transmission of FIG 98, D _1-2, D _2-1, another with D _2-2 channel Broadcasting programs C, B, and A in this manner, it is possible to reliably broadcast the simulcast of program D in all regions, and to provide the effect of multi-program broadcasting by serving the other three programs while fulfilling the role of simulcast. Can be

One feature of the hierarchical transmission system of the present invention is to improve the frequency use efficiency, but the power use efficiency is considerably reduced for some receivers. Therefore, it cannot be applied to all transmission systems. For example, in the case of a satellite communication system between specific receivers, the most economical method is to replace the equipment with the highest frequency use efficiency and highest power use efficiency obtained at that time. In such a case, it is not always necessary to use the present invention.

However, in the case of a satellite broadcasting system or a terrestrial broadcasting system, a hierarchical transmission system as in the present invention is required. This is because satellite broadcasting standards require persistence of 50 years or more. During this period, the broadcasting standard is not changed, but the transmission power of the satellite is dramatically improved with technological innovation. Broadcasting stations must provide compatible broadcasting so that manufactured receivers can receive and view TV programs in the future several decades from now. Using the present invention, the existing NTS
The effects of compatibility between C broadcast and HDTV broadcast and expandability of future information transmission amount can be obtained.

Although the present invention places importance on frequency efficiency rather than power efficiency, transmission is performed by setting several types of receivers each having a designed receiving sensitivity according to each transmission stage on the receiver side. There is no need to increase the power of the machine so much.
For this reason, even a satellite with a small current power can transmit sufficiently. Further, even if the transmission power increases in the future, transmission can be performed according to the same standard, so that future expandability and compatibility between new and old receivers can be obtained. As described above, the present invention has a remarkable effect when used in the satellite broadcasting standard.

When the hierarchical transmission system of the present invention is used for terrestrial broadcasting, the present invention is easier to implement than satellite broadcasting because there is no need to consider power use efficiency at all. As described above, the conventional digital HDTV broadcasting system has a remarkable effect of greatly reducing the unreceivable area in the service area and the effect of compatibility between the NTSC and the HDTV receiver or the receiver. Also, there is an effect that the service area as viewed from the sponsor of the TV program is substantially expanded. In the embodiment, QPSK, 16QAM and 3
Although the description has been given using the example using the modulation method of 2QAM,
It goes without saying that the present invention can be applied to 4QAM, 128QAM, 256QAM and the like. It goes without saying that the present invention can be applied to multi-valued PSK, ASK, and FSK as described with reference to the drawings. Although the embodiment in which the present invention is combined with TDM for transmission has been described, transmission may also be performed by combining FDM, CDMA and spread communication systems.

[0259]

As described above, the present invention provides a signal input unit,
A transmission device for performing data transmission, comprising: a modulation unit that modulates a plurality of carriers having different phases with an input signal from the input unit to generate an m-valued signal point on a signal vector diagram, and a transmission unit that transmits the modulated signal. In step (1), a first data string and a second data string of n values are input, the signal is divided into n signal point groups, and the signal point groups are assigned to data of the first data strings, respectively. Allocating each data of the second data group to each signal point in, transmitting a signal by a transmitting transmitter,
The signal point is divided into n-valued signal points in a receiving device having an input portion of the transmission signal, a demodulator for demodulating a QAM modulated wave of a p-valued signal point on a signal space diagram, and an output portion. The first data string of the signal point group n value is correlated and demodulated, and the data of the second data string of the p / n value is demodulated and reproduced at the signal point of substantially the p / n value in the signal point group and received. By transmitting data using the device, for example, the modulator 4 of the transmitter 1 divides the n-valued first data string, the second data string, and the third data string into signal point groups and modifies the data. QA of value
The first receiver 23 transmits an M-modulated signal, and a demodulator 25
The first data string of the n value is calculated by the
The data sequence and the second data sequence are demodulated by the third receiver 43 into the first data sequence, the second data sequence, and the third data sequence. Even if the receiver has only the demodulation capability of n <m, where n <m, a transmission device capable of demodulating n-value data and having compatibility and development can be obtained. Further, when the distance between the signal point closest to the origin and the I-axis or the Q-axis among the signal points of the QAM method is f, the signal point is shifted so that the distance becomes nf such that n> 1. , Hierarchical transmission becomes possible.

By transmitting an NTSC signal to the transmission system as a first data sequence and a difference signal between HDTV and NTSC as a second data sequence, in satellite broadcasting, NTSC broadcasting and HDTV broadcasting are compatible. Digital broadcasting with a high scalability can be achieved, and terrestrial broadcasting has a remarkable effect of expanding a service area and eliminating an unreceivable area.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating an entire system of a transmission device according to a first embodiment of the present invention.

FIG. 2 is a block diagram of a transmitter 1 according to the first embodiment of the present invention.

FIG. 3 is a vector diagram of a transmission signal according to the first embodiment of the present invention.

FIG. 4 is a vector diagram of a transmission signal according to the first embodiment of the present invention.

FIG. 5 is a diagram illustrating assignment of codes to signal points according to the first embodiment of the present invention.

FIG. 6 is a coding diagram for a signal point cloud according to the first embodiment of the present invention.

FIG. 7 is a coding diagram for signal points in a signal point group according to the first embodiment of the present invention.

FIG. 8 is a diagram illustrating coding of signal points and signal points according to the first embodiment of the present invention.

FIG. 9 is a threshold state diagram of a signal point group of a transmission signal according to the first embodiment of the present invention.

FIG. 10 is a vector diagram of modified 16-value QAM according to the first embodiment of the present invention.

FIG. 11 is a diagram illustrating a relationship between an antenna radius r ₂ and a transmission power ratio n according to the first embodiment of the present invention.

FIG. 12 is a diagram of signal points of modified 64-value QAM according to the first embodiment of the present invention.

FIG. 13 is a diagram illustrating a relationship between an antenna radius r ₃ and a transmission power ratio n according to the first embodiment of the present invention.

FIG. 14 is a vector diagram of a signal group of modified 64-QAM and a group of sub-signal points according to the first embodiment of the present invention;

FIG. 15 is an explanatory diagram of ratios A ₁ and A ₂ of modified 64-value QAM according to the first embodiment of the present invention.

FIG. 16 is a relationship diagram between antenna radii r ₂ and r ₃ and transmission power ratios n ₁₆ and n _{64 according to} the first embodiment of the present invention.

FIG. 17 is a block diagram of a digital transmitter according to the first embodiment of the present invention.

FIG. 18 is a signal space diagram diagram of 4PSK modulation according to the first embodiment of the present invention.

FIG. 19 is a block diagram of a first receiver according to the first embodiment of the present invention.

FIG. 20 is a signal space diagram diagram of a 4PSK modulated signal according to the first embodiment of the present invention.

FIG. 21 is a block diagram of a second receiver according to the first embodiment of the present invention.

FIG. 22 is a signal vector diagram of modified 16-value QAM according to the first embodiment of the present invention.

FIG. 23 is a signal vector diagram of modified 64-value QAM according to the first embodiment of the present invention.

FIG. 24 is a flowchart according to the first embodiment of the present invention.

25A is a signal vector diagram of 8-level QAM according to the first embodiment of the present invention. FIG. 25B is a signal vector diagram of 16-level QAM according to the first embodiment of the present invention.

FIG. 26 is a block diagram of a third receiver according to the first embodiment of the present invention.

FIG. 27 is a diagram of signal points of modified 64-value QAM according to the first embodiment of the present invention.

FIG. 28 is a flowchart according to the first embodiment of the present invention.

FIG. 29 is an overall configuration diagram of a transmission system according to a third embodiment of the present invention.

FIG. 30 is a block diagram of a first image encoder according to Embodiment 3 of the present invention.

FIG. 31 is a block diagram of a first image decoder according to a third embodiment of the present invention;

FIG. 32 is a block diagram of a second image decoder according to Embodiment 3 of the present invention.

FIG. 33 is a block diagram of a third image decoder according to the third embodiment of the present invention.

FIG. 34 is an explanatory diagram of time multiplexing of D ₁ , D ₂ , and D ₃ signals according to the _third embodiment of the present invention.

FIG. 35 is an explanatory diagram of time multiplexing of D ₁ , D ₂ , and D ₃ signals according to the _third embodiment of the present invention.

FIG. 36 is an explanatory diagram of time multiplexing of D ₁ , D ₂ , and D ₃ signals according to the _third embodiment of the present invention.

FIG. 37 is a configuration diagram of an entire system of a transmission device according to a fourth embodiment of the present invention.

FIG. 38 is a vector diagram of signal points of modified 16QAM in Embodiment 3 of the present invention.

FIG. 39 is a vector diagram of signal points of modified 16QAM in Embodiment 3 of the present invention.

FIG. 40 is a vector diagram of signal points of modified 64QAM in Embodiment 3 of the present invention.

FIG. 41 is a signal arrangement diagram on a time axis according to the third embodiment of the present invention.

FIG. 42 is a signal arrangement diagram on the time axis of the TDMA system according to the third embodiment of the present invention.

FIG. 43 is a block diagram of a carrier recovery circuit according to a third embodiment of the present invention;

FIG. 44 is a view showing the principle of carrier recovery according to the third embodiment of the present invention;

FIG. 45 is a block diagram of an inverse modulation type carrier recovery circuit according to a third embodiment of the present invention.

FIG. 46 is a signal point arrangement diagram of a 16QAM signal according to the third embodiment of the present invention.

FIG. 47 is a signal point arrangement diagram of a 64QAM signal according to the third embodiment of the present invention.

FIG. 48 is a block diagram of a 16-multiplier carrier recovery circuit according to a third embodiment of the present invention;

FIG. 49 shows D _V1 , D _H1 , D _V2 , and D _V1 of Embodiment 3 of the present invention.
Illustration of time multiplexing of D _H2 , D _V3 , and D _H3 signals

FIG. 50 shows D _V1 , D _H1 , D _V2 , and D _V1 of Embodiment 3 of the present invention.
Explanatory diagram of TDMA time multiplexing of D _H2 , D _V3 , and D _H3 signals

FIG. 51 shows D _V1 , D _H1 , D _V2 , and D _V1 of Embodiment 3 of the present invention.
Explanatory diagram of TDMA time multiplexing of D _H2 , D _V3 , and D _H3 signals

FIG. 52 is a diagram showing a reception interference area of the conventional system in the fourth embodiment of the present invention.

FIG. 53 is a diagram of a reception obstruction area in the case of a hierarchical broadcasting system according to the fourth embodiment of the present invention.

FIG. 54 is a diagram showing a reception interference area of the conventional system in the fourth embodiment of the present invention.

FIG. 55 is a diagram of a reception obstruction area in the case of a hierarchical broadcasting system according to the fourth embodiment of the present invention.

FIG. 56 is a digital broadcast station 2 according to the fourth embodiment of the present invention.
Station jamming area diagram

FIG. 57 is a signal point arrangement diagram of a modified 4ASK signal according to the fifth embodiment of the present invention.

FIG. 58 is a signal point arrangement diagram of modified 4ASK in the fifth embodiment of the present invention.

FIG. 59 (a) is a variation 4A in the fifth embodiment of the present invention.
SK signal point arrangement diagram (b) is a signal point arrangement diagram of modified 4ASK in the fifth embodiment of the present invention.

FIG. 60 is a signal point arrangement diagram of a modified 4ASK signal in the case of a low C / N value in the fifth embodiment of the present invention.

FIG. 61 is a block diagram of a transmitter according to a fifth embodiment of the present invention.

FIG. 62 (a) is a frequency distribution diagram of an ASK modulation signal according to the fifth embodiment of the present invention, and (b) is a frequency distribution diagram of an ASK modulation signal according to the fifth embodiment of the present invention.

FIG. 63 is a block diagram of a receiver according to a fifth embodiment of the present invention.

FIG. 64 is a block diagram of a video signal transmitter according to a fifth embodiment of the present invention.

FIG. 65 is a block diagram of an entire TV receiver according to a fifth embodiment of the present invention.

FIG. 66 is a block diagram of another TV receiver according to the fifth embodiment of the present invention.

FIG. 67 is a block diagram of a satellite / terrestrial TV receiver according to a fifth embodiment of the present invention.

FIG. 68 is a signal point arrangement diagram of an 8-level ASK signal in Embodiment 5 of the present invention.

FIG. 69 is another block diagram of an image encoder in Embodiment 5 of the present invention.

FIG. 70 is a block diagram of an image encoder with one separation circuit in Embodiment 5 of the present invention.

FIG. 71 is a block diagram of an image decoder according to Embodiment 5 of the present invention.

FIG. 72 is a block diagram of one image decoder of a synthesizer according to a fifth embodiment of the present invention.

FIG. 73 is a time allocation diagram of a transmission signal according to the fifth embodiment of the present invention.

FIG. 74 (a) is a block diagram of an image decoder according to Embodiment 5 of the present invention; FIG. 74 (b) is a time allocation diagram of transmission signals of Embodiment 5 according to the present invention;

FIG. 75 is a time allocation diagram of a transmission signal according to the fifth embodiment of the present invention.

FIG. 76 is a time allocation diagram of a transmission signal according to the fifth embodiment of the present invention.

FIG. 77 is a time allocation diagram of a transmission signal according to the fifth embodiment of the present invention.

FIG. 78 is a block diagram of an image decoder according to a fifth embodiment of the present invention.

FIG. 79 is a time allocation diagram of transmission signals of three layers according to the fifth embodiment of the present invention.

FIG. 80 is a block diagram of an image decoder according to Embodiment 5 of the present invention.

FIG. 81 is a time allocation diagram of a transmission signal according to the fifth embodiment of the present invention.

FIG. 82 is a block diagram of a D1 image decoder according to Embodiment 5 of the present invention.

FIG. 83 is a frequency-time diagram of the frequency modulation signal of the fifth embodiment according to the present invention.

FIG. 84 is a block diagram of a magnetic recording / reproducing apparatus according to a fifth embodiment of the present invention.

FIG. 85 is a diagram showing the relationship between the C / N and the layer number according to the second embodiment of the present invention.

FIG. 86 is a diagram showing the relationship between the transmission distance and C / N according to the second embodiment of the present invention.

FIG. 87 is a block diagram of a transmitter according to a second embodiment of the present invention.

FIG. 88 is a block diagram of a receiver according to a second embodiment of the present invention.

FIG. 89 is a relationship diagram of C / N-error rate according to the second embodiment of the present invention.

FIG. 90 is a diagram of a three-layer reception interference area according to the fifth embodiment of the present invention.

FIG. 91 is a diagram showing a 4-layer reception interference area according to the sixth embodiment of the present invention.

FIG. 92 is a hierarchical transmission diagram according to a sixth embodiment of the present invention.

FIG. 93 is a block diagram of a separation circuit according to a sixth embodiment of the present invention.

FIG. 94 is a block diagram of a synthesis unit according to a sixth embodiment of the present invention.

FIG. 95 is a transmission hierarchical structure diagram of Embodiment 6 according to the present invention.

Fig. 96 is a reception state diagram of a conventional digital TV broadcast.

FIG. 97 is a reception state diagram of digital TV hierarchical broadcasting according to Embodiment 6 of the present invention.

FIG. 98 is a transmission hierarchical structure diagram of Embodiment 6 according to the present invention.

FIG. 99 is a vector diagram of 16 SRQAM of Embodiment 3 according to the present invention.

FIG. 100 is a vector diagram of 32 SRQAM of Embodiment 3 according to the present invention.

FIG. 101 is a diagram showing a C / N-error rate relationship according to a third embodiment of the present invention.

FIG. 102 is a diagram showing a relationship between C / N and an error rate according to the third embodiment of the present invention.

FIG. 103 is a diagram illustrating a relationship between a shift amount n and C / N required for transmission according to a third embodiment of the present invention.

FIG. 104 is a diagram illustrating a relationship between a shift amount n and C / N required for transmission according to a third embodiment of the present invention.

FIG. 105 is a diagram illustrating a relationship between a distance from a transmitting antenna and a signal level during terrestrial broadcasting according to the third embodiment of the present invention.

FIG. 106 is a diagram illustrating a service area of 32 SRQAM according to a third embodiment of the present invention.

FIG. 107 is a service area diagram of 32 SRQAM of Embodiment 3 according to the present invention.

FIG. 108 is a TV signal frequency distribution diagram according to the third embodiment of the present invention.

FIG. 109 is a diagram illustrating a TV signal time arrangement according to the third embodiment of the present invention.

FIG. 110 is a diagram showing the principle of the C-CDM according to the third embodiment of the present invention.

FIG. 111 is a diagram showing code assignment according to a third embodiment of the present invention.

FIG. 112 is a diagram showing code assignment when 36QAM is extended according to the third embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 transmitter 4 modulator 6 antenna 6a terrestrial antenna 10 satellite 12 repeater 23 first receiver 25 demodulator 33 second receiver 35 demodulator 43 third receiver 51 digital transmitter 85 signal point 91 first split signal point Group 401 First image encoder 703 Reception area of SRQAM 708 Reception area of conventional method 722 Carrier 725 Spectrum

──────────────────────────────────────────────────続 き Continued on the front page (31) Priority claim number Japanese Patent Application No. 3-182236 (32) Priority date July 23, 1991 (July 23, 1991) (33) Priority claim country Japan (JP) (31) Priority claim number Japanese Patent Application No. 4-60739 (32) Priority date March 17, 1992 (1992.3.17) (33) Priority claim country Japan (JP) (56) References JP JP-A-64-74836 (JP, A) JP-A-53-108215 (JP, A) JP-A-63-28145 (JP, A) JP-A-64-68144 (JP, A) JP-A-53-137657 (JP, A) JP-A-53-132927 (JP, A) JP-A-51-47311 (JP, A) JP-A-57-159148 (JP, A) JP-A-5-276211 (JP, A) 64-5135 (JP, A) Table 8-8-506473 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04L 27/00-27/38 H04L 1/00

Claims (4)

(57) [Claims] 1. A signal output from a transmitting apparatus that modulates, modulates, multiplexes, and transmits a signal by changing the number of signal points allocated on a space diagram for each of a plurality of data strings, as an input signal, wherein the input signal is the plurality of data strings. Wherein the first data sequence includes demodulation information for demodulating a modulated signal obtained by modulating a data sequence other than the first data sequence, and the demodulation information includes a data sequence other than the first data sequence. A demodulation unit that demodulates the input signal, a data sequence reproduction unit that reproduces the plurality of data sequences from an output of the demodulation unit, and an output of the data sequence reproduction unit. A demodulation control unit that controls the demodulation unit based on the demodulation information extracted from the first data sequence; and an output control unit that controls provision of a service obtained from the plurality of data sequences. A modulation / demodulation control unit that controls the demodulation unit based on a signal score corresponding to a modulated signal obtained by modulating a data sequence other than the first data sequence; and an output control unit that performs reception C / N (signal-to-noise). A service which sequentially stops services obtained from a data string having a low error resilience as the ratio decreases. 2. The receiving device according to claim 1, further comprising: an output unit that outputs a service obtained from the plurality of data strings based on control of the output control unit. 3. The receiving device according to claim 2, further comprising a providing unit that provides an output of the output unit as video information or audio information. 4. A receiving method in which a signal which is modulated by changing the number of signal points to be allocated on a space diagram for each of a plurality of data strings, and a signal multiplexed and transmitted is used as an input signal, wherein the input signal is The first data sequence in the data sequence includes demodulation information for demodulating a modulated signal obtained by modulating a data sequence other than the first data sequence, and the demodulation information is other than the first data sequence. Including a signal number corresponding to a modulated signal obtained by modulating a data sequence, demodulating the input signal, reproducing the first data sequence,
The demodulation information is extracted from the reproduced signal of the first data sequence, and the data sequence other than the first data sequence is determined based on the number of signal points corresponding to the modulated signal obtained by modulating the data sequence other than the first data sequence. And demodulating a modulated signal obtained by modulating the above, and sequentially stopping services obtained from a data string with low error resilience as the reception C / N (signal-to-noise ratio) deteriorates.