JPS6376588A - Information transmission system and its equipment - Google Patents

Abstract

PURPOSE:To reduce the interference between the video signals and the multiplex signals of neighboring broadcastings by shifting in frequency both the carrier wave spectrum modulated with multiplex-transmitted signal and the carrier wave spectrum modulated with the video signal of a neighboring broadcasting. CONSTITUTION:A voice signal to be multiplexed is supplied to an input terminal 13, and the signal is converted to a digital signal by an ADC 14. In a digital signal processing circuit 15, a code to detect and correct errors that may occur during transmission is added to the said digital signal, as well as an interleaving processing is applied likewise, then, unnecessary components are eliminated from the digital signal by means of a filter 16 suitable for the transmission rate of the digital code. A PSK modulator 37 modulates the carrier wave for transmitting digitally coded voice signals which is supplied from a carrier wave generator 18 with the said digital coded voice, and the result is added with a video signal by an adder 19, then transmitted from an antenna 20. As a result, a digital coded voice of a high quality can be multiplex-transmitted in a ground television broadcasting.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a multiplex transmission system, and particularly relates to a multiplex transmission system that transmits digitally encoded audio and high-frequency signals to terrestrial television broadcasting that transmits video signals and audio signals. The present invention relates to a transmission method and device effective for multiplex transmission of other signals such as fine video signal information.

[Conventional technology]

Digitally encoded audio and video signals are reported by the Satellite Broadcasting Receiving Technology Investigation Committee, edited by the Radio Technology Association, Part 1.
Using a subcarrier of 5.7272MHz for the video signal of
Since the commercial audio is multiplexed, it does not satisfy the bandwidth of the current terrestrial television broadcasting, and it is difficult to use it for terrestrial television broadcasting. Regarding the method of multiplexing digitally encoded audio to television broadcasts, pp. 1020-102 of EIMPTK Journal A/ (Journal), October 1985.
5A, ``Digital Stereo Sound with Terrestrial Television'' announced by Howarcf Jones.
ere.

5ound with Terrestrial T
eLevision).

[Problem that the invention seeks to solve]

The above conventional technology addresses interference between broadcasts that are adjacent in frequency and space, such as at the boundaries of television broadcasting service areas, by lowering the power of the carrier wave of the signal that multiplexes digitally encoded audio. However, conversely, no consideration was given to interference from video signals of adjacent broadcasts, and there were problems such as multiplexing of broadcasts adjacent to the IA in the G range, and 2) narrowing of the signal boobys area.

SUMMARY OF THE INVENTION An object of the present invention is to provide an information transmission system and apparatus for reducing interference between video signals and multiplexed signals of adjacent broadcasts in television broadcasts that are adjacent to each other in frequency and space.

[Failure to solve the problem]

The above purpose is to shift the frequency of the carrier wave spectrum modulated by the multiplexed signal and the carrier wave spectrum modulated by the adjacent broadcasting video signal, so that the peaks of the two spectra do not match. achieved.

[Effect]

Since the carrier spectrum modulated by the multiplexed signal and the carrier spectrum modulated by the adjacent broadcast video signal do not match, there is little interference in signal amount.

Furthermore, it becomes possible to reduce interference by using a comb filter on the receiving side to extract necessary signals and remove unnecessary signals.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a television signal transmission device according to a first embodiment of the present invention. An audio signal digitally coded as a signal to be multiplexed will be explained using phase, seven-foot, keying (hereinafter abbreviated as PSK) as an example of a transmission method for multiplexing.

1 is an audio signal input terminal, 2 is an FM modulator, 3 is an audio signal carrier generator, 24 is a video signal input terminal, 5 is a
) Tx circuit, 6 is a luminance signal processing circuit, 7 is a color difference signal processing circuit, 8 is an addition circuit, 9 is a video modulator, 10 is a video signal carrier generator, and 11 is a vestigial sideband width modulation circuit. VS
B filter, 12 is an adder, 15 is an input terminal for an audio signal to be digitally encoded and transmitted, 14 is an analog/digital exchanger (hereinafter abbreviated as ADC), 15 is a digital signal processing circuit, 16 is a filter, 17 is a PI3 18 is a carrier wave generator for audio signals to be PC digitally encoded and transmitted, 19 is an adder, and 20 is an antenna.

The audio signal from the audio signal input terminal 1 converts the audio carrier wave from the audio signal carrier wave generator 6 into FM in the 7M modulator 2.
Modulate. The three primary color signals of RGB input to the video input terminal 4 are divided into a luminance signal and a color difference signal by a matrix 5, processed by a luminance signal processing circuit 6 and a color difference signal processing circuit 7, and then added by an adder 8. The carrier wave from the video signal carrier generator 10 is modulated by the signal after the addition using the video modulator 9, band-limited to the television gene broadcast band by the WEB filter 11, and added to the audio signal by the adder 12.

The above is the same as conventional terrestrial television broadcasting. High-quality audio with more signals than above.

Add the following to transmit.

Add the audio signal to be multiplexed to the input terminal 16, and send the audio signal to A.
The DC 14 converts it into a digital signal, and the digital signal processing circuit 15 adds a code to detect and correct errors that occur during transmission, and performs interleaving processing.
Unnecessary components are removed through a filter 16 suitable for the transmission rate of the digital code. With this digitally encoded audio, the carrier wave from the carrier wave generator 18 for the audio signal to be digitally encoded and transmitted is modulated by the PEIK modulator 57, added to the video signal etc. by the adder 19, and then
Transmit 0. As a result, high-quality digitally encoded audio can be multiplexed and transmitted for terrestrial television broadcast reception.

FIG. 2 shows an embodiment of a receiver that receives the signals transmitted in the above embodiments.

21 is an antenna, 22 is a high frequency amplification circuit, 25 is a frequency conversion circuit, 24 is an intermediate frequency amplification circuit, 25 is a video signal/signal detection circuit, 26 is a video signal detection circuit, 27 is a color difference signal demodulation circuit, 28 is a primary color signal Demodulation circuit, 29 is a cathode ray tube,
50 is an audio intermediate frequency amplification circuit, 31 is an audio FM detection circuit, 52 is an audio signal output terminal, 36 is a filter 64 is a PS
K demodulation circuit, 55 is a carrier wave regeneration circuit, 66 is a code identification circuit, 67 is a clock regeneration circuit, 38 is a digital signal processing circuit, 39 is a digital to analog conversion circuit (hereinafter referred to as D).
(abbreviated as AC), 40 is an output terminal for digitally encoded and transmitted audio signals.

A television signal inputted from an antenna 21 is amplified by a high frequency amplifier circuit 22, frequency-converted by a frequency conversion circuit 23 to an intermediate frequency for demodulation, and amplified by an intermediate frequency amplifier circuit 24. Tuning is performed by changing the local oscillation frequency of the frequency conversion circuit 23. The video signal band from the signal amplified by the intermediate frequency amplification circuit 24 is detected by the video signal detection circuit 25, and primary colors are detected from the luminance signal output from the video signal amplification circuit 26 and the color difference signal output from the color difference signal demodulation circuit 27. The signal demodulation circuit takes two days to obtain the three primary colors R, G, and B, and displays them on the cathode ray tube 29.

On the other hand, the audio signal band is amplified by the audio intermediate frequency amplification circuit 60, and then detected and tuned by the audio FM detection circuit 61 to obtain an audio signal at the audio signal output terminal 32.

The above is the same as the conventional television digital reception if).

In addition to the above, in order to demodulate the digitally encoded audio signal, the digitally encoded audio signal band multiplexed and transmitted from the output of the frequency conversion circuit 23 is selected and amplified by the filter 65. , PSK demodulation is performed using the carrier wave regenerated by the carrier wave regeneration circuit 65.

A code identification circuit 36 converts the resulting signal into a digital code at a point with a low error rate, and a digital signal processing circuit 38 detects and corrects errors occurring during transmission using an error detection and correction code. The clock regeneration circuit 67 is PSK
This circuit extracts the transmission lock from the output signal of the demodulation circuit 64, and extracts the digitally coded and modulated spectrum at the point where the error rate of the signal output from the PEAK demodulation circuit 34 is low (so-called maximum aperture 2 of the eye pattern). 3 and 4. In FIG. 3, 41 is the spectrum of the video signal after the VSB filter, 42 is the spectrum of the FM modulated audio signal, 43 is the spectrum of the audio signal that is digitally encoded and transmitted, 44 and 45 shown with broken lines are 6MH
These are spectra of video and audio signals of adjacent channels separated by one. Here, the spectrum that is digitally encoded and transmitted is a transmission rate of 1 Mbit/s, 4-phase P
The case of aK (hereinafter abbreviated as QPSK) is shown.

In the figure, the carrier frequency of the video signal of the own channel is O
Indicated as Hz. -Q for video carrier wave, VS with residual sideband amplitude modulation for spectrum below 75MHz
It is attenuated by the B filter.

Video signals are distributed up to 4.2MHz, and 4.5MHz
In the vicinity of z, there is an FM-modulated spectrum of the audio signal. The spectrum of a digitally encoded and transmitted audio signal is closely related to the data transmission rate, and when transmitted with Qpsx modulation of 1 Mbit/sec, the required bandwidth is about 500 KHz. Now, set the carrier frequency to 5. IM
If Hz is selected, the required frequency width will be 4.6MHz - 5.6MHz.

Furthermore, the transmission level will be considered using the carrier level to noise ratio (hereinafter referred to as CN ratio). CN ratio of video signal 4
Assuming that 0 dB is the practical reception level, the 4 MHz video signal detection circuit has a transmission bandwidth of approximately 500 KHz, which is approximately 8 times the transmission bandwidth of the audio signal that is digitally encoded and transmitted.
The CN ratio of the PSK signal is 49 dB.

On the other hand, when considering the relationship between the CN ratio and the bit error rate of Digital No. 1 using general QPSK, the CN ratio is 11. Jd
B is IF', and 37~ as a digital signal transmission.
There is also a sub-digit of 8dB. Even if the carrier wave level is lowered by 50 dB to reduce interference with the video signal of the adjacent channel than the digitally encoded and transmitted audio signal, the
There is a 3dB subdigit.

Next, interference between signals will be roughly explained using FIG. 4, which is a detailed enlarged view of the vicinity of 5 MHz and 6 MHz in FIG. 5. (α) and ('J 46 and 47 shown in the figure are the audio signal spectra to be digitally encoded and multiplexed,
+41 48 indicated by a broken line in the figure is an image of an adjacent channel.

This is an image signal spectrum. The video signal spectrum of the adjacent channel is determined by the horizontal synchronization frequency fH (15,734
KHz) and the vertical synchronization frequency fV, so the fH synchronization and fV same period spectra are concentrated, as shown by the broken line 48. On the other hand, the digitally encoded audio signal is also manipulated to have a correlation with fH, as shown in curve 46, or by creating an inverse correlation, as shown in song @47.

I'm going to growl. Using this relationship, (in the case of the diagram, for example, 5
Between the frequency of 5.119MHz with 6 times lower fH and the frequency of 5.119MHz with 57 times lower fH, 105MHz5,
46 and 48 by setting the K carrier frequency to 111MHz.
The spectrum can be multiplexed with less interference. Also fc
In the case of Figure 1, the carrier frequency is set to 5. By setting the IO to 3 MHz, the spectrum of 47 and 48 can be multiplexed and transmitted with less interference.

Interference when receiving and demodulating signals transmitted in this manner will be explained using FIGS. 5 to 7. In FIG. 5, reference numeral 49 indicates the video intermediate frequency amplitude characteristics of the five receivers, and 50, indicated by a broken line, indicates the video intermediate frequency amplitude characteristics of the receiver receiving the adjacent channel. Residual Sideband Amplitude Modulation (WERE
), both 4pi
e, the band for transmission is the video carrier frequency,
By detecting the video signal after having the intermediate frequency characteristic shown in the song θ17I9 which is attenuated by 5 dB, the frequency characteristic after detection is flattened. Since the audio signal spectrum 45 that is digitally encoded and multiplexed is attenuated by the video intermediate frequency amplitude characteristic 50 of the adjacent channel receiver, it is not possible to demodulate the audio signal that is digitally encoded and transmitted by the receiver that is receiving the adjacent channel. can reduce interference to video signals.

In FIG. 6, reference numeral 51 indicates an intermediate frequency amplitude characteristic for receiving and demodulating a digitally encoded and multiplex-transmitted audio signal. The lower sideband of the video signal spectrum 44 transmitted by vestigial sideband amplitude modulation (VSB) of the adjacent channel comes within the passband of the intermediate frequency amplitude characteristic 51 of the receiver.
The detailed characteristics of the intermediate frequency amplitude characteristic 51 are shown at 52 in FIG. 7, and by providing it with a comb-shaped characteristic having fH same-period debugs, it is possible to further reduce interference caused by video signals of adjacent channels.

As explained above, according to this embodiment, since the frequency is set so that the video signal spectrum of adjacent television broadcasting and the audio signal spectrum to be digitally encoded and multiplexed transmission are difficult to match on the spectrum, This has the effect of reducing interference.

One means of concentrating the spectrum of a digitally encoded audio signal at certain frequency intervals will be explained using FIGS. 8 to 10. 61 is an input terminal, 62 is a time axis compression circuit, 63 is a timing generation circuit, 64 is a delay circuit, 65 is a changeover switch, 66 is an output terminal, 6/ is a data string of input terminal 61, and 68 is an output of compression circuit 62 A data string, 69 is an output data string of the delay device 64, 70 is an output data string of the changeover switch 65, 71 is an output data string of the changeover switch 65 when the output of the delay device 64 is inverted, 72 is a data string 7
0 is the spectrum, and 76 is the spectrum of the data string 71. A data string 67 applied to an input terminal 61 is subjected to time axis compression by a time axis compression circuit 62 at the timing of a timing generation circuit 65, and is converted into intermittent data shown in a data string 68. When this intermittent data is added to a data string 69 delayed by a delay time 2, that is, 5 data in a delay circuit 64, by a changeover switch 65, a data string 70 is obtained.

This data string 70 is exactly the same as the data string 68 in which delayed data is inserted into a period in which there is no data string, and has a correlation with the delay time 2. As a result, a spectrum shown by a curve 72 shown in FIG. 10 is obtained. When this vector is modulated using a carrier wave, it becomes as shown in (αJ) in FIG. As a result, as shown in the curve 73 shown in Fig. 10, a spectrum with ÷, !, 4 mountain and river delay! If the same data is transmitted during intermittent data as described above, the data transmission speed will be doubled.

In order to reduce the increase in the data transmission speed and to provide spectrum delag, it is also possible to transmit two or three of the five data of CLQ k a4 in between. In this case, although the increase in data transmission speed can be reduced, the amount of delag cannot be expected to be as large as shown in curves 72 and 73. However, since the spectrum delag frequency is determined by the delay time 1, curves 72 and
Same as 3.

Next, the implementation when demodulating the data strings 70 and 71.

An example will be explained using FIGS. 11 and 12. 74 is an input terminal, 75 is a timing demodulation circuit, 76 is a changeover switch, 77 is a time axis expansion circuit, 78 is an output terminal, 79 is a changeover switch, 80 is a delay circuit, 81 is a coincidence detection circuit,
82 is a coincidence detection output. By switching the selector switch 76 at the timing when the data strings 70 and 71 in FIG. In FIG. 12, since the data strings 68 and 69 are obtained by the changeover switch 79, coincidence is detected by the delay circuit 80 and the coincidence detection circuit 81, and a coincidence detection output 82 is obtained. Data strings 68 and 69 match if no error occurs during signal transmission, but if an error occurs during signal transmission, a match detection circuit 81 detects a cine match using that data and outputs it to a match detection output 82. get. The coincidence detection circuit can be formed of a KOR gate or the like.

In addition, the delay time related to the spectrum dilag frequency! When the relationship between and the data transmission rate is not synchronized,
can be absorbed by providing a period during which no data is transmitted, such as between 44 and α0 of the data string 7o or between 44 and 5 of the data string 71.

Another embodiment of the invention is shown in FIG. Reference numeral 90 is a frequency conversion circuit, and reference numeral 91 is a local oscillator, and the same reference numerals as in FIG. 1 indicate the same functions. The frequency of the output of the adder 19 is increased by the oscillation shoulder wave number fo of the local oscillator 91 by a frequency conversion circuit 90. Therefore, according to this embodiment, the oscillation frequency of carrier wave generators 3.10 and 18 for each modulation signal is f
Since the signal is generated by lowering 0, deterioration in modulation accuracy due to the frequency characteristics of each transformer 2, 9, and 17 is reduced, and a stable transmission signal can be obtained.

Similarly, an embodiment that improves the stability of the receiver is shown in FIG. 92 is a filter, 93 is a frequency conversion circuit, and the same symbols as in FIG. 2 indicate the same functions. The difference from FIG. 2 is that a filter 92 and a frequency conversion circuit 93 are provided in order to lower the frequency for demodulating the digitally encoded and multiplexed audio signal than the frequency for demodulating the video signal.

According to this embodiment, the intermediate frequency of the output of the frequency conversion circuit 3 (58.75 MHz for Japanese terrestrial television)
Since the video signal is demodulated using the frequency conversion circuit 23 (which is commonly used), and the audio signal digitally encoded and multiplexed is demodulated using the lower frequency intermediate side V<, for example, 5MH2ifij of the output of the frequency conversion circuit 23. P.S.
The phase error caused by the circuit delay time of the carrier wave regenerated by the carrier wave regeneration circuit 35 used in the K demodulation circuit 54 is reduced by lowering the frequency, making it possible to stably digitally encode and demodulate multiplexed audio signals. There is an effect that can be done.

Still another embodiment of the present invention is shown in FIG. In this embodiment, digitally encoded and multiplexed signals are transmitted in a manner that prevents them from interfering with video signals of adjacent channels.

FIG. 2 is a block diagram of a transmitter that has been reduced to two monkeys for reception.

94 is a filter with inverse characteristics to the reception comb filter, and those having the same symbols as those in FIG. 16 are shown with @ in the same place.

Furthermore, the same effect can be obtained by providing a filter with inverse characteristics to the comb-shaped filter of a similar receiver at the output of the PBK modulator shown in FIG. At the receiver, a comb filter on the receiver side shown in FIG. 7 deletes the video signal of the adjacent channel shown in H in FIG. extract the audio signal. At that time, the margin characteristic near the dip of the comb filter shown in Fig. 7 is the (
G) Slightly degrades the characteristics near the dip in the spectrum of ``digital data error rate caused by transmission''.

It may cause deterioration. In order to reduce its deterioration,
In FIG.
According to this embodiment, the output of the signal is transmitted via the inverse characteristic filter 9A, and the effect of receiving the audio signal with less interference to the audio signal digitally encoded and multiplexed from the video signal of the adjacent channel is transmitted. be.

Another embodiment of the receiver according to the present invention is shown in FIG. 95 is a frequency conversion circuit, 95 is a mixer, 96 is a reference oscillator, 97 is a phase detector, 98 is a low-pass filter, 99
is a voltage controlled oscillator, and the same symbols as in FIGS. 2 and 14 indicate the same functions. The signal converted to an intermediate frequency by the frequency conversion circuit 6 and passed through the filter 90 is sent to the mixer 9
5 and a voltage controlled oscillator 99, the frequency is further converted, and after passing through the filter 33, the phase difference between the output of the reference oscillator 9 and the phase detector 97 is detected, and the voltage is passed through the low-pass filter 98. Feeds back to the control oscillator.

With this negative feedback loop, the voltage controlled oscillator 9 inputs the PSK demodulator 140 to the frequency of the reference oscillator 96.
The oscillation frequency of 9 changes. This frequency change is convenient in the following cases, and is also a new effect of this embodiment. Now, the television broadcasting station that transmits the first digitally encoded audio is TV1, and the station adjacent to the frequency above it is TV2. It is assumed that the television broadcasting station transmitting the second digitally encoded audio is 'rva' and the station adjacent to the frequency above it is 'rv5. Also, TV+ and TV
2 has a frequency interval of 5MHz, 'rv5 has an offset of +i QKHz to account for interference with other areas, and the frequency interval between TV4 and Tv50 is 5MHz. (HMHz
shall be. At this time, when the transmission carrier wave of the digitally encoded audio signal according to the present invention has the tc+ spectrum shown in FIG. 4, interference with adjacent channels on 6 MHz is reduced as shown in FIG. In order to do this, we set the carrier wave for the audio signal to be digitally encoded and multiplexed to 5,133 MH2 above the video signal.
In order to reduce interference with adjacent channels on the video signal, the carrier wave of the audio signal is set to be digitally encoded and multiplexed at 11 AMHz above the video signal. That is, TVl
The digital audio carrier wave is 5 times higher than the video signal carrier wave.
The digital audio carrier wave of TV4 is 5,115 MHz above the video signal carrier wave. When receiving these television broadcasts, the local oscillation frequency of the frequency conversion circuit 3 is changed using a tuning dial or the like, and the intermediate frequency of the video signal is generally set to 58.75 MHz.

At this time, if upper local is used as the local oscillation circuit, the intermediate frequency a of digital audio in TV1 is 58.75M.
5. from H1. IQ3MHz lower 5' 5.647MHz, TV4 is 5.11 than 58.75MHz! +MHz lower to 55.6.37MHz. Assuming that the oscillation frequency of the reference oscillator 96 in FIG.
9,147MHz, TV40: 59,157
MHz and 1QKHz different frequency tonatte control. As a result, PSK'ffl frequency 9J5.5MHz
Therefore, the characteristic of the filter 16 is 5.5MHz.
In other words, f3 in Fig. 7 is set to 5,
Just set it to 5111H2, 1i of adjacent Nayanel
The same effect can be obtained even if an offset of 0 KHz is set. Furthermore, the stability of broadcasting station frequencies such as neighboring stations is 1×1.
0 or less, which is less than IKHz by an element.

According to this embodiment, even if the offsets of adjacent channel frequencies are set to different values between broadcasting stations, it is possible to efficiently reduce interference from adjacent channels.

As an example of the PSY-demodulation circuit 14 and the phase detector 97, the case of QPSK is shown in FIG.
(abbreviated as ) is shown in FIG. 18.

FIG. 17 shows an example of demodulating a QPSK signal.

100V'i, input terminal, 101 is the first phase detector,
102° is the second phase detector, 103 is the 96 phase shifter, 1
04 is the first judgment circuit, 105 is the second judgment circuit, 1
06 is.

107 is a first demodulated output, 108 is a first multiplier, 109 is a second multiplier, and 110 is a subtracter. Components with the same symbols as in FIG. 16 indicate the same functions. A mixer 95 is used to beat down the signal applied to the input terminal 100 and the voltage controlled oscillator 99, and a filter 33 removes unnecessary out-of-band noise and interference. The output is sent to the first phase detector 101 and the second phase detector 102.
In addition, the reference oscillator 960 phase and its output are synchronously detected through a 90' phase shifter 103 with signals having a phase shift of 90 degrees, and are converted into baseband signals with a phase of 0 degrees and a phase of 90 degrees, respectively. Those signals are sent to the first judgment circuit 104.
The signal is determined to be 1' or -1 by the second determination circuit 105, and is obtained as a first demodulation output 106 and a second demodulation output 107, respectively, as a 21-digit digital signal. - 10,000, 1st
The output of the phase detector 101 and the output of the second determination circuit 105 are added to the first multiplier 108, and the output is added to the subtracter 1.
10, and the output of the second phase detector 102 and the output of the first determination circuit 104 are connected to the second multiplier 109.
In addition to.

The output is used as the other input of the subtracter 110. Subtractor 1
The output of 10 is fed back to the voltage controlled oscillator 99 via a loop filter 9. That is, the first multiplier 10, the second multiplier 109, the subtractor 110 and the low-pass filter 9
8, the first phase detector 101 and the second phase detector 1
A negative feedback loop that detects the phase difference between the intermediate frequency input to the oscillator 96 and the output of the reference oscillator 96, controls the voltage controlled oscillator 99, and adjusts the phase difference between the intermediate frequency and the output of the reference oscillator 96 to a certain degree. It constitutes. The phase difference detection operation is described in Japanese Unexamined Patent Publication No. 197944/1982, and therefore will not be described here.

2. If one input of the first multiplier 108 and the second multiplier 10 has a sufficient limiter effect, the signals from the output of the first discrimination circuit 104 and the output of the second discrimination circuit 105 will be The same operation is performed for the output of the phase detection circuit and the second phase detection circuit.

An example of demodulating the BPSK multiplied signal is shown in FIG. 18. 6 Components with the same symbols as in FIG. 17 have the same functions. 111 is a multiplier. The signal applied to the input terminal 1 is converted to an intermediate frequency, and passed through the filter 36 to the first phase detector 10.
In addition to the first and second phase detectors 102, the outputs of the reference oscillator 96 and the phase shifter 103 are used to compare the phase with the signal whose phase has been shifted by 908, and the outputs of the first phase detector 101 and the second The output of phase detector 102 is applied to multiplier 111 for multiplication, and this output is fed back to voltage controlled oscillator 99 via low-pass filter 98 . .

As a result, the frequency of the intermediate frequency becomes the reference oscillator 960 frequency, resulting in stable characteristics.

Note that one of the inputs of the multiplier 111 is connected to the first phase detector 10.
1 output, but instead the first determination circuit 104
A similar operation and effect can be obtained with the output of .

The above describes the transmission and reception of digitally encoded audio signals using the PSX system.
A similar effect can be obtained with digital transmission methods using carrier waves such as .

Also, although the explanation was given using a digitally encoded sound P signal as No. 18 to be multiplexed, other signals may also be used (for now).

In particular, if a spectrum having an fH same period correlation and a peak at fH frequency intervals, such as a high-definition video signal over the current transmission band, is transmitted using the carrier wave shown in the present invention, it can be received and reproduced with less interference with the 14-multiple channel.

〔Effect of the invention〕

According to the present invention, since the multiplexed signal spectrum and the spectrum of the adjacent broadcast video signal do not match, it is possible to reduce interference caused by other signals when the receiver receives the necessary signal. That is, it is possible to reduce interference from video signals of adjacent broadcasts when receiving multiplexed signals, and to reduce interference due to multiplexed signals when receiving adjacent broadcasts.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of an embodiment of the present invention, and FIG. 2 is a diagram. FIG. 3 is a spectral diagram for explaining the present invention, FIG. 4 is a spectrum diagram for explaining the present invention, and FIG. 5 is a block diagram of an embodiment of the receiving side for carrying out the present invention. FIG. 6 is a characteristic diagram of a filter for receiving multiplexed signals for explaining the present invention; FIG. 7 is a characteristic diagram of a filter for receiving multiplexed signals for explaining the present invention; FIG. 8 is a block diagram for concentrating the spectrum of the present invention, FIG. 9 is a diagram for detailed explanation of the present invention, and FIG. 10 is a detailed diagram of the present invention. An explanatory spectrum diagram, FIG. 11 is a diagram of one configuration example of the data demodulation circuit of FIG. 8 of the present invention, and FIG.
FIG. 13 is a configuration diagram of another embodiment of the present invention, and FIG. 14 is a configuration diagram of another embodiment of a receiver for implementing the present invention. , FIG. 15 is a block diagram of still another embodiment of the present invention, FIG. 16 is a block diagram of another three receivers for implementing the present invention, and FIG. 17 is a block diagram of another embodiment of the present invention. FIG. 1B is a block diagram of an embodiment of a BPSK demodulation circuit of a receiver for implementing the present invention. 14...ADC. 15...Digital signal processing circuit, 16...
Filter, 17...PSK modulation circuit, 18...Carrier wave generator. 19... Adder, 62... Time axis compression circuit, 64... Delay device. 65... Selector switch, 77... Time axis expansion circuit, 90... Frequency conversion circuit, 94... Inverse characteristic filter. Brown 3 Figure surrounding pattern (1'1l-h) Part S Figure solid trap (Ken 2) Rimo Otsu ■] , / Hon - Surrounding moat η (r”IHA) Chopstick dust Figure ha Figure 8 9 Figure 100 70 Figure θ φ φ 4 Shoulder 5Lψ (English lt Figure 1/2 Figure 7

Claims (1)

[Claims] 1. In terrestrial television broadcasting in which an audio signal is transmitted by frequency modulating a video signal using residual sideband amplitude modulation, a sideband is generated in the gap between the sideband spectra of broadcasting stations adjacent in frequency and space. An information transmission system characterized by providing a carrier wave that is modulated by another signal that has a wave spectrum arranged in frequency. 2. In claim 1, the frequency of the carrier wave is higher than the occupied bandwidth by the vestigial sideband amplitude modulation and the frequency modulation, and the frequency of the carrier wave is higher than the occupied bandwidth by the vestigial sideband amplitude modulation and frequency modulation, and the vestigial sideband is generated at the frequency and the video signal of a spatially adjacent broadcast station An information transmission method characterized in that the frequency is lower than the video signal carrier frequency that is amplitude modulated. 3. An apparatus for receiving multiplexed broadcast according to claim 1 or 2, which multiplexes the broadcast so that the modulation spectrum of the carrier wave has a dip at the horizontal synchronization frequency interval of the video. What is claimed is: 1. An information transmission device comprising: a signal processing circuit for correlating the signals in the horizontal synchronization frequency of the video signal. 4. Information according to claim 3, characterized in that a comb filter for extracting multiplexed signals and an inverse characteristic filter having an inverse characteristic to reduce deterioration of transmission characteristics caused by the filter are provided. Transmission device.