JPH0879321A - Digital signal transmitter, digital signal transmission method and digital signal transmitter-receiver - Google Patents

Abstract

PURPOSE: To send a digital signal within a standardized frequency band when the digital signal is sent by adopting the infrared ray transmission system. CONSTITUTION: The transmitter is provided with a QPSK modulation circuit 13 having roll-off filters 132, 133 and a digital modulation signal S2 whose band is made narrow is formed by applying roll-off filter processing and QPSK modulation processing to an input digital signal. An infrared ray signal whose frequency band is set within the standardized frequency band is obtained by driving an infrared ray emitter based on a digital modulation voice signal S2.

Description

Detailed Description of the Invention

[0001]

[Table of Contents] The present invention will be described in the following order. Field of Industrial Application Conventional Technology Problem to be Solved by the Invention (FIG. 11) Means for Solving the Problem Action Example (1) First Example (FIGS. 1 to 7) (2) Second Example (FIGS. 8 and 9) (3) Other Embodiments (FIG. 10) Effects of the Invention

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital signal transmission device, a digital signal transmission method and a digital signal transmission / reception device, and is suitable for application in the case of transmitting a digital voice signal by a radio transmission system, for example.

[0003]

2. Description of the Related Art As an audio signal transmission method of this kind, there is an infrared transmission method. In the infrared transmission method, the audio signal is frequency-modulated on the transmitting side, and the infrared optical emitter is driven based on the frequency-modulated signal to generate a transmission audio signal. On the receiving side, the transmitted voice signal is received by the infrared receiver and then demodulated. As a result, in this type of audio signal transmission method, a desired audio signal can be collectively transmitted to a large number of audio devices without requiring a transmission line,
For example, it is used for wireless headphone and speaker device.

[0004]

However, in the conventional infrared transmission method, since the audio signal is analog-modulated and transmitted, there is a problem that the signal is easily deteriorated. As a method for solving such a problem, an audio signal transmission method for transmitting a high-quality digital audio signal by an infrared transmission method by driving an infrared optical emitter with a digital audio signal is disclosed by the present applicant in US Patent No.
Proposed in 5,394,259.

However, in this type of audio signal transmission method, a digital audio signal originally transmitted by using a coaxial cable or an optical fiber or an EFM (Eight to Fourteen Modu) signal is used.
The modulated digital audio signal is used as it is to drive the infrared optical emitter. For this reason, there is a problem that the frequency band of the digital audio signal thus obtained cannot comply with the subcarrier frequency allocation for infrared transmission defined in CP-1205 of the Japan Electronic Machinery Manufacturers' Association.

That is, in CP-1205, frequency allocation (subcarrier) as shown in FIG. 11 is defined.
The remote control signal in the band of 0.33 to 0.4 [MHz] is 0.4 to 1
Conference system signals and analog audio signals in the [MHz] band, various data in the 1-2 [MHz] band, 2
High-quality audio signals in the band of ~ 6 [MHz]
[z]], the video signals are respectively transmitted. In this way, the digital audio signal is 2 to 6 [MH
z]] must be transmitted within the frequency band [z], but conventional digital audio signals are also transmitted using bands other than this frequency band.

The present invention has been made in consideration of the above points, and when a digital audio signal is transmitted using an infrared transmission system, it can be transmitted within a standardized frequency band and is desired at the receiving side. It is intended to propose a digital signal transmission device, a digital signal transmission method, and a digital signal transmission / reception device that can obtain the signal characteristics of FIG.

[0008]

In order to solve such a problem, in the present invention, a means for serial / parallel converting a digital signal to generate an I component signal and a Q component signal, and the I component signal and the Q component signal. And a roll-off filter having a predetermined roll-off ratio for narrowing the band by means of a filter process, and a means for performing two-phase phase modulation on each of the I-component signal and the Q-component signal after the filter process.
K modulation means is provided, and infrared rays are generated by driving the infrared emitter based on the digital modulation signal supplied from the QPSK modulation means.

Further, in the present invention, according to the predetermined importance of the data included in the digital signal,
Data division means for dividing the digital signal into a plurality of data, QPSK modulation means for performing roll-off shaping and QPSK modulation for each of the divided data, and for each of the divided data BPSK modulation means for performing roll-off shaping and BPSK modulation,
16QAM modulation means for performing roll-off shaping and 16QAM modulation on one of the divided data,
Addition means for adding the data after the BPSK modulation, the data after the 16QAM modulation and the data after the QPSK modulation is provided, and infrared rays are generated by driving the infrared emitter based on the digital modulation signal supplied from the addition means. To do so.

[0010]

The digital signal is band-limited to a predetermined frequency band by being modulated by the QPSK modulation means having the roll-off filter. Therefore, if the infrared emitter is driven based on this band-limited digital modulation signal, an infrared signal within the standardized frequency band can be obtained.

Further, different modulation processing (QPSK modulation, 16QAM modulation, BPSK modulation) is performed according to the importance of the data of the digital signal, so that the transmission distance becomes longer as the importance of the data increases. Therefore, the receiving side can receive a natural voice whose sound quality gradually deteriorates as the distance from the transmitting side increases. As a result, desired signal characteristics can be obtained on the receiving side.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

(1) First Embodiment In FIG. 1, reference numeral 1 denotes an audio signal transmission apparatus for transmitting a digital audio signal as a whole by an infrared transmission system,
The digital audio signal S1 output from the digital audio device 2 is input to the transmitter 3 via a coaxial cable or an optical fiber.

In the transmitter 3, first, the digital audio signal S1 conforming to IEC-958 (DIO) by IEC (International Electrotechnical Commission) is reformatted into a structure suitable for infrared transmission. In DIO, this is 3.072 [Mp
bs] × 2 (multiplied by 2 is for Biphase conversion), so there is data with a transmission rate, so the bandwidth is 3 to 6 [MHz]
Because it does not fit in.

The re-formatted signal is digitally modulated, and the modulated audio signal S2 thus obtained is sent to the infrared light emitter 4. The infrared light emitter 4 is composed of an amplifier circuit, a light emitting diode (or laser diode), a lens, an optical filter, and the like, and the modulated audio signal S
By being driven based on 2, the optical transmission signal S3 composed of infrared rays is generated.

The optical transmission signal S3 is composed of an optical filter, a lens,
A modulated audio signal S4 is generated by the infrared light receiver 5 including a photo diode (or a photo transistor) and an amplifier circuit.
And the modulated audio signal S4 is input to the receiver 6. The receiver 6 performs a process reverse to that performed by the transmitter 3 and demodulates the modulated audio signal S4 to form a demodulated audio signal S5 having a data structure similar to that of the digital audio signal S1. An analog audio device 7 and / or a digital audio device 8 which is a speaker device or the like for the audio signal S5 via a coaxial cable or an optical fiber.
Send to.

Here, the transmitter 3 is constructed as shown in FIG. That is, the transmitter 3 supplies the input digital audio signal S1 to the re-formatting circuit 12 via the input circuit 10 and the parity adding circuit 11. The parity adding circuit 11 adds error correction parity to the digital audio signal S7, and supplies the resulting digital audio signal S9 to the re-format circuit 12.

The re-formatting circuit 12 saves the block structure of IEC-958 (DIO) after removing unnecessary data or duplicated data from the digital audio signal S9, for example, block sync signal or subframe sync signal, and further needs it. If so, a predetermined bit stream is formed by adding an error correction parity. As a result, the re-formatting circuit 12 can narrow the band of the digital audio signal S9 by removing unnecessary data, and can also add error correction data to the digital audio signal S9.
Here, the block structure of DIO is shown in FIG.

The transmitter 3 also supplies the digital audio signal S1 to the clock conversion circuit 15 via the input circuit 10. The clock conversion circuit 15 is composed of a PLL circuit, a frequency dividing circuit, a frequency multiplying circuit, and the like. The channel clock S8 is generated by performing an appropriate conversion based on the information on whether the number increases (preset).

In practice, the digital audio signal S1 is reproduced from a digital audio device 2 (FIG. 1) such as a digital processor, a compact disc reproducing device and a digital audio tape recorder (DAT), and the sampling frequency is 32 [kHz]. , 44.056 [kHz], 44.1 [kHz] or 48 [kHz], quantization bit is 20 [bits] to 24 [bits]
s], the signal has a transmission rate of 3.072 [Mbps] when the sampling frequency is 48 [kHz] (that is, the strictest condition when limiting the frequency band of the signal), that is, IEC
It is a digital audio signal conforming to IEC-958 by (International Electrotechnical Commission).

QPSK (Quadrature Phase Shift Keyin
g) The re-format signal S10 output from the re-format circuit 12 and the channel clock S8 obtained by the clock conversion of the sampling frequency signal S6 are input to the modulation circuit 13. Then, the QPSK modulation circuit 13 applies the four-phase phase modulation to the re-formatted signal S10 with reference to the channel clock S8, thereby keeping the re-formatted signal S10 within the predetermined frequency range.

In this way, the QPSK modulation circuit 13 allocates the digital audio signal S1 as a high-quality audio transmission band as shown in FIG.
A modulated audio signal S2 whose frequency band is within 3 [MHz] to 6 [MHz], avoiding 2.3 [MHz] and 2.8 [MHz] assigned to analog headphones etc. in the [MHz] band To.

Here, a specific configuration of the QPSK modulation circuit 13 is shown in FIG. The re-format signal S10 is supplied to the input terminal of the switch SW1. The switch SW1 selects either the terminal a or the terminal b based on the channel clock S8. That is, channel clock S8
Corresponds to a sampling frequency of 44.056 [kHz] or 44.1 [kHz], the terminal a is selected and 32 [kHz] or 48 [kHz]
z], the terminal b is selected.

Although the switch SW1 is controlled on the basis of the channel clock S8 here, the switch SW1 may be controlled by using the data clock S6. This is because the sampling frequency of the digital audio signal S1 can be known by using either the channel clock S8 or the data clock S6. Therefore, it suffices if the sampling frequency can be known. Therefore, if the signal included in the IEC-958 (DIO) is a signal capable of discriminating the sampling frequency, any signal can be used by the switch SW1. You may switch.

As a result, the sampling frequency is 44.056 or 44.1.
At [kHz], the re-formatted signal S10 is directly input to the serial / parallel conversion circuit 131. On the other hand, when the sampling frequency is 32 or 48 [kHz], it is input to the serial / parallel conversion circuit 131 via the patching circuit 130. The patterning circuit 130 has 32
Even if the data of [kHz] is input, the data is read by the channel clock corresponding to the sampling frequency of 48 [kHz] to form the data block.

However, since the data of 32 [kHz] is read by the channel clock corresponding to 48 [kHz], the data cannot be completely filled in one block. Therefore, the patterning circuit 13
0 performs a so-called patching process of inserting waste data. Incidentally, at this time, 1/3 of the block becomes waste data. By performing the patching process in this way, a signal of 32 [kHz] can be handled as a signal of 48 [kHz] and can be processed by a pair of roll-off filters. As a result, the structure can be simplified.

The re-format signal S10 is serial /
In the parallel conversion circuit 131, I data S11 and Q
The data S12 is converted into parallel data. The I data S11 and the Q data S12 are the roll-off filter 13 respectively.
2, 133. Roll-off filter 1 here
32A and 133A have sampling frequencies 44.056 and 44.1
The signal of [kHz] is regarded as a signal corresponding to one sampling frequency, and the filter processing is performed. This is because the sampling frequencies of these two signals are very close.

Roll-off filters 132B and 13B
3B performs filter processing corresponding to a signal of 48 [kHz]. Switching between these two types of filters is performed in the switches SW2 and SW3 in the same manner as in the switch SW1. I data S13 after filter processing,
The Q data S14 is supplied to the multiplication circuits 134 and 135, respectively.

The multiplying circuit 134 multiplies the carrier wave f _C generated by the carrier wave generating circuit 136 by the I data S13 and sends the resulting modulated signal S15 to the adding circuit 138. On the other hand, the multiplication circuit 135 multiplies the carrier wave f _C whose phase is shifted by π / 2 by the phase shifter 139 and the Q data S14, and outputs the resulting modulated signal S16 to the addition circuit 138. Thus, the adder circuit 138 allows the modulated signal S1
By adding 5 and S16, the carrier wave f _C is QPS by the digital audio signal (reformatted signal) S10.
A K-modulated modulated audio signal S2 is obtained.

In this embodiment, the roll-off rate of the two pairs of roll-off filters 132 and 133 is 20 to 30%.
As a result, in the QPSK modulation circuit 13, it is possible to obtain a transmission amount enough to add an error correction parity.

The modulated audio signal S2 output from the QPSK modulation circuit 13 is sent to the succeeding infrared light emitter 4 (FIG. 1) via the amplifier circuit 14. Thus, the optical transmission signal S3 within the standardized frequency band can be output from the infrared light emitter 4.

Thus, in the transmitter 3, 20 to 30
Roll-off filter 13 having a roll-off rate of [%]
By combining the filter processing according to 2, 133 and the QPSK modulation processing, the digital audio signal can be effectively contained within the standardized frequency. This will be described with reference to FIG. FIG. 6 (A) shows a signal when a signal having a sampling frequency of 48 [kHz] is simply modulated by QPSK. In this case, the carrier frequency f _C
(For example, 4.5 [kHz]), the band is 3.072
[MHz] Therefore, the digital voice signal cannot be contained within 3 to 6 [MHz] simply by QPSK modulation.

Therefore, in the transmitter 3, the band is further narrowed by combining the roll-off filter process and the QPSK modulation process. FIG. 6B shows the characteristics of the roll-off filter. Digital audio signal from 3 [MHz] to 6
It is necessary to reduce the roll-off rate in order to put it within [MHz] and add a predetermined amount of error correction code, but it is difficult to actually realize a steep one, so 20-30 [%] Is suitable. Therefore, in this embodiment, the roll-off rate is set to this value. Note that FIG.
In (B), f _ch represents a channel clock frequency on the transmission path, and T _ch represents a symbol time interval.

FIG. 6C shows a digital audio signal stored within 3 [MHz] to 6 [MHz] by combining the roll-off filter processing and the QPSK modulation processing as in this embodiment. It should be noted that the reason that a slight margin (guard band) is provided at both ends of the signal is to allow for the case where processing is performed by a band pass filter (not shown) on the receiving side.

Here, the receiver 6 is constructed as shown in FIG. That is, the receiver 6 sends the modulated audio signal S4 output from the infrared receiver 5 to the QP via the amplifier circuit 20.
It is input to the SK demodulation circuit 21 and the carrier wave detection circuit 22.
The QPSK demodulation circuit 21 demodulates the modulated audio signal S20 while referring to the carrier signal S22 detected by the carrier detection circuit 22, thereby re-formatting the signal S.
The demodulated audio signal S21 is formed by a bit stream similar to that of 10 (FIG. 2), and the demodulated audio signal S21 is sent to the format restoring circuit 23.

The format restoring circuit 23 performs a process reverse to that of the re-formatting circuit 12 to form a demodulated voice signal S21 into a digital voice signal S23 conforming to IEC-958 and an error correction circuit for the digital voice signal S23. 24. The error correction circuit 24 corrects the error generated at the time of transmission by using the error correction parity included in the digital audio signal S23, and sends the resulting digital audio signal S24 to the output circuit 25.

At this time, the error correction circuit 24 checks whether or not the error can be corrected. When the error cannot be corrected, the output control signal S25 is sent to the output circuit 25 to stop the output operation of the output circuit 25. Incidentally, in the case of this embodiment, the Reed-Solomon code is used for the error correction parity, and in order to enable error detection, the correctable range r with respect to the correction code distance d is given by

[Equation 1] Set as shown in, and correct the error within this range.

Further, the output circuit 25 outputs the digital audio signal S
The demodulated audio signal S5 is formed by converting the data rate of 24 into a value suitable for the audio equipment in the subsequent stage, and this is output.

In the above configuration, the transmitter 3 of this embodiment stores a signal of 3.072 [Mbps] in the frequency band 3 [MHz] to 6 [MHz] as follows. First, the transmitter 3 removes unnecessary data from the input digital audio signal. The transmitter 3 also adds error correction parity to the data. At this time, the amount of data increases as compared with the original signal by the amount of unnecessary data subtracted from the parity.

Next, the transmitter 3 performs QPSK modulation processing on such data. When this QPSK modulation processing is performed, the roll-off filter processing is performed on the digital audio signal at a roll-off rate of 20 to 30%. As a result, if the roll-off rate is set to 30 [%], for example, the carrier frequency f _C (= 4.5 [MHz])
A modulated voice signal having a bandwidth of 2.0 [MHz] to 2.6 [MHz] can be formed. Note that this bandwidth varies slightly with the amount of parity.

Thus, according to the above configuration, IEC-9
By applying the roll-off filter process and the QPSK modulation process to the digital audio signal S1 conforming to 58, it can be kept within the frequency band conforming to the standard of infrared transmission. Therefore, in the infrared transmission device 1, by driving the infrared emitter 4 based on the modulated audio signal S2 obtained as a result, the optical transmission signal S3 conforming to the infrared transmission standard can be obtained.

Further, since the digital audio signal S1 having four kinds of sampling frequencies is processed by the two roll-off filters, the structure can be simplified. The roll-off rate of each roll-off filter is 20%
By selecting 30%, it is possible to add an error correction code within a predetermined transmission amount.

(2) Second Embodiment In FIG. 8 in which parts corresponding to those in FIG. 2 are assigned the same reference numerals, 100 indicates the transmitter of the second embodiment as a whole and corresponds to the transmitter 3 of FIG. To do. The transmitter 100 sends the input digital audio signal S1 to the data shunt circuit 31 of the parity adding circuit 30 via the input circuit 10. The data shunt circuit 31 sends the most important data to the error code adding circuit 32A and the next important data to the error code based on the importance of the data contained in the digital audio signal S1 (determined by the DIO format). The less important data is sent to the addition circuit 32B and the error code addition circuit 32C, respectively.

The error code adding circuit 32A adds a large amount of error correction parity to the input data, and the error code adding circuit 32C adds a small amount of error correction parity to the input data and an error code adding circuit. 32B adds an error correction parity smaller than the error code adding circuit 32A and larger than the error code adding circuit 32C.

The data output from the error code adding circuits 32A to 32C is input to the re-formatting circuit 12 via the multiplexer 33. The data re-formatted by the re-formatting circuit 12 as described above is sent to the QPSK modulation circuit 13 and the QPSK
By being modulated by the modulation circuit 13, it is contained in a frequency band conforming to the standard of infrared transmission, and is output as a modulated audio signal S15.

In practice, among the data contained in the digital audio signal S1 conforming to IEC-958, the data such as user bits, valid bits, and status bits are very important. Therefore, the data shunt circuit 31 makes an error in these data. It is sent to the code addition circuit 32A. In the sampling data, MSB (Most Significant
Since the importance decreases from bit) to LSB (Least Significant bit), the data is distributed from the error code adding circuit 32A to the error code adding circuit 32C in this order.

As a result, the data to which a large amount of error correction parity is added has a higher correction capability than other data when the same bit error rate occurs during transmission, and therefore is easily restored on the receiving side. On the other hand, data with a small error correction parity is difficult to be restored due to its low restoration ability. In other words, in the transmitter 100, the data included in the digital audio signal S1 is weighted.

In the transmitter 100, so-called graceful derailleur can be realized by utilizing this. That is, when the infrared optical emitter 4 is driven based on the modulated audio signal S15 formed by the transmitter 100 of this embodiment, the sound quality is sequentially increased from the data with less error correction parity on the receiving side as the distance between the transmitting side and the receiving side increases. Deteriorates. As a result, the transmitter 100 does not suddenly cut off all the voices when the distance from the receiver 6 exceeds a certain value, but has an effect that the sound quality of the analog voice signal gradually deteriorates. Therefore, natural sound can be supplied to the receiving side. Further, in the transmitter 100, the transmission distance can be freely adjusted according to the application by presetting the addition amount of the error correction parity to a desired value, and the usability can be improved.

In the above configuration, the transmitter 100 sorts the data according to the importance of the data contained in the digital audio signal S1. Next, with respect to the distributed data, a large amount of error correction parity is added to high importance data, and the amount of error correction parity added to low data is reduced.

Next, the data to which the error correction parity is added is QPSK-modulated, and the resulting modulated audio signal S1 is obtained.
By supplying 5 to the infrared light emitter 4 (FIG. 1), an optical transmission signal S3 is obtained. In the optical transmission signal S3 thus obtained, as shown in FIG. 9, as the distance to the receiver increases, the amount of data reaching the receiver gradually decreases. It is possible to receive a natural sound close to that in the case of analog transmission shown by.

According to the above configuration, the more important data is, the more error correction parity is added to the data, and the QPSK is added.
By performing the modulation, graceful resolution can be realized and the sound quality on the receiving side can be significantly improved.

(3) Other Embodiments (3-1) In the second embodiment described above, the data included in the digital audio signal S1 is sorted according to the importance, and the data having the higher importance is used for error correction. Although the case has been described in which graceful degradation is realized by adding a large number of parities, the present invention is not limited to this. For example, the transmitter 3 (FIG. 1) has a configuration as shown in FIG. The 200 may be used to realize graceful degra- ration by multi-carrier transmission.

That is, in FIG. 10 in which parts corresponding to those in FIG. 3 are designated by the same reference numerals, the transmitter 200 sends the re-formatted signal S10 output from the re-formatted circuit 12 to the data shunting circuit 41 to determine the importance of the data. Divide into multiple data according to frequency. The shunted data is modulated by the digital modulation section 42 by a different modulation method, and is stored in the standard frequency band. Modulator 4 here
2 is a BPSK (Binary Phase Shift Keying) modulation circuit 42A, a QPSK modulation circuit 42B and a 16QAM (Qu
adrature Amplitude Modulation) Modulation circuit 42C may be used. Further, in each of the modulation circuits 42A to 42C, the waveform shaping by the roll-off filter is performed similarly to the above-mentioned embodiment.

Here, the ratio of the data amount of each modulation method is determined based on the following concept. That is, when a digital audio signal is transmitted only by QPSK modulation, this QP
When the bandwidth in SK modulation is standardized to “1” and the transmission data amount is standardized to “1”, and the data ratios of BPSK modulation, QPSK modulation and 16QAM modulation are x, y and z, the data amount is The following formula

[Equation 2] And the bandwidth is

(Equation 3) Holds. Therefore, the ratio of the data amount of each modulation method can be obtained from these two equations. In order to transmit the same amount of data as in QPSK modulation, the BPSK modulation requires a double band, and the 16QAM modulation requires only a half band. Therefore, the bandwidth (2) is satisfied.

The modulation signals S30A to S30C output from the digital modulation circuits 42A to 42C are added by the adder circuit 4.
It is supplied to the infrared light emitter through the amplifier 3 and the amplifier circuit 14. Thus, the graceful derailleur can be realized by changing the data transmission distance for each modulation method.

(3-2) In the above embodiment,
Although the roll-off filters 132 and 133 are provided after the serial / parallel conversion circuit 131 and before the phase modulation by the carrier wave in consideration of the ease of implementation of the QPSK modulation circuit 13, the present invention is not limited to this. Instead, it may be provided after the phase modulation.

In the above embodiment, the case where the QPSK modulation circuit 13 of the transmitter 3 is provided with a roll-off filter having a roll-off rate of 20 to 30 [%] has been described, but the present invention is not limited to this. A roll-off filter may be provided on each of the modulation side and the demodulation side. In this case, if the roll-off filter on the modulation side and the roll-off filter on the demodulation side are combined, the roll-off rate is 20 to 30 [%].
Each roll-off filter may be configured so that That is, the roll-off can be realized on the entire transmission line. Normally, a filter having a root roll-off characteristic equally distributed to the transmitting side (modulation side) and the receiving side (demodulation side) may be used.

(3-3) In the above embodiment,
The case where the digital audio signal S1 conforming to IEC-958 is contained in the frequency band defined by the standard and is infrared-transmitted has been described, but the present invention is not limited to this, and other data, for example, a mini disk (MD). It can also be applied to the case of transmitting infrared data such as Atrac data obtained by the apparatus, data obtained by a digital compact cassette (DCC), computer data, and the like, and the same effect as the above-mentioned embodiment can be obtained. Further, these data can be identified by having a header.

(3-4) If a return function is added to the receiving side, the light emitting direction of the transmitting side can be controlled according to the receiving state of the receiving side, and the usability can be further improved. Further, according to the above-described embodiment, by narrowing the frequency band of the transmission signal, noise can be reduced and the error rate can be improved, and as a result, an effect of extending the transmission distance when viewed at the same transmission output can be obtained. be able to. The same effect can be obtained by performing narrow-angle transmission with the infrared light emitter 4. This is effective when the receiving side is fixed like a speaker.

(3-5) In the above embodiment,
The digital audio device 2, the transmitter 3, and the infrared light emitter 4 are separately provided, and the analog audio device 7, the digital audio device 8 and the infrared light receiver 5,
Although the case where the receiver 6 is provided separately has been described, the present invention is not limited to this, and the transmitter 3 and the infrared light emitter 4 are provided in the digital audio equipment 2, and the infrared light receiver 5 and the receiver 6 are analog. It may be provided in the audio device 7 or the digital audio device 8.

[0061]

As described above, according to the present invention, means for serial / parallel converting a digital signal to generate an I component signal and a Q component signal, and a filter process for the I component signal and the Q component signal. And a roll-off filter having a predetermined roll-off ratio, which narrows the band by applying
A QPSK modulator is provided that includes a component for phase-modulating the component signal and a component for modulating the Q-component signal, and infrared rays are generated by driving the infrared emitter based on the digitally modulated signal supplied from the QPSK modulator. By doing so, it is possible to realize a digital signal transmission device capable of infrared-transmitting a digital signal within a standardized frequency band.

Further, according to the present invention, a plurality of modulation means which respectively perform different modulation processing and each have a roll-off filter are provided in accordance with the predetermined importance of the data included in the digital signal, and each modulation is performed. By driving the infrared emitter based on the digital modulation signal modulated by the means, the digital signal can be infrared-transmitted within the standardized frequency band and desired signal characteristics can be obtained on the receiving side. It is possible to realize a digital signal transmission device capable of

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of an audio signal transmission system using a digital signal transmission device according to the present invention.

FIG. 2 is a block diagram showing a configuration of a transmitter according to an embodiment.

FIG. 3 is a schematic diagram showing a data block structure of the DIO standard.

FIG. 4 is a schematic diagram showing a frequency band of an optical transmission signal output from the audio signal transmission device according to the embodiment.

FIG. 5 is a block diagram showing a configuration of a QPSK modulation circuit according to an embodiment.

FIG. 6 is a schematic diagram for explaining a roll-off filter process according to an example.

FIG. 7 is a block diagram showing a configuration of a receiver according to an embodiment.

FIG. 8 is a block diagram showing a configuration of a transmitter according to a second embodiment.

FIG. 9 is a characteristic curve diagram showing a relationship between a distance to a receiver and data to be reached, which is used for explaining the graceful derailleur.

FIG. 10 is a block diagram showing a configuration of a transmitter according to another embodiment.

FIG. 11 is a schematic diagram showing a frequency allocation standard for infrared transmission.

[Explanation of symbols]

1 ... Audio signal transmission device, 3, 100, 200 ... Transmitter, 4 ... Infrared light emitter, 5 ... Infrared receiver, 6
...... Receiver, 10 …… Input circuit, 11,30 …… Parity addition circuit, 12 …… Reformat circuit, 13 …… Q
PSK modulation circuit, 21 ... QPSK demodulation circuit, 23 ...
Format restoration circuit, 24 ... Error correction circuit, 32A
32C ... Error code addition circuit, 41 ... Data shunt circuit, 42A ... BPSK modulation circuit, 42B ... QP
SK modulation circuit, 42C ... 16QAM modulation circuit, 130
...... Putting circuit, 131 …… Serial / parallel conversion circuit, 132,133 …… Roll-off filter, 1
36 ... Carrier wave generation circuit, SW1 to SW3 ... Switcher, S1 ... Digital audio signal, S2, S4, S1
5, S30A to S30C ... Modulated audio signal, S3 ... Optical transmission signal, S5 ... Demodulated audio signal, S6 ... Sampling frequency signal, S8 ... Channel clock, S10 ... Reformat signal, S11 ... I data, S12 ... Q data.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location H04L 27/22 9297-5K H04L 27/22 Z

Claims (21)

[Claims] 1. Input means for receiving a digital signal of a predetermined transmission rate, means for serial / parallel converting the digital signal received by said input means to generate an I component signal and a Q component signal, and said I signal. A roll-off filter having a predetermined roll-off ratio for filtering the component signal and the Q-component signal to narrow the band, and the I-component signal and Q after the filter processing.
QPSK modulation means including means for respectively performing two-phase phase modulation on the component signals, and infrared rays are generated by driving the infrared emitter based on the digital modulation signal supplied from the QPSK modulation means, and the infrared rays are generated by the external device. An infrared transmitting means for transmitting a digital signal, comprising: a digital signal transmitting device. 2. The roll-off rate of the roll-off filter is approximately 20 to 30%.
The digital signal transmission device as described in. 3. The digital signal is 32 [kHz], 44.0
The signal has a sampling frequency of 56 [kHz], 44.1 [kHz] and / or 48 [kHz], and the QPSK modulating means converts the digital signal to 3 [MH].
The digital signal transmission device according to claim 1, wherein the digital signal transmission device is within a frequency band of z] to 6 [MHz]. 4. The digital signal comprises signals of first and second sampling frequencies having a sampling frequency ratio of m: n (m> n, m and n are positive integers). 2. The digital signal transmission device according to claim 1, wherein the modulation means comprises a patterning means for patterning the signal of the second sampling frequency and processing it as the signal of the first sampling frequency. 5. The digital signal further comprises signals of third and fourth sampling frequencies whose sampling frequencies are close to each other, and the roll-off filter outputs the signal of the first sampling frequency. A first roll-off filter for roll-off shaping, and a second roll-off filter for performing roll-off shaping by regarding signals of the third and fourth sampling frequencies as one sampling frequency, and Switch means for selecting either the output of the first roll-off filter or the output of the second roll-off filter and supplying the selected signal to the means for phase modulating the two phases. Claim 4
The digital signal transmission device as described in. 6. The sampling frequencies of the first, second, third and fourth digital signals are 32 [kHz] and 48 [k], respectively.
6. The digital signal transmission device according to claim 5, wherein the signals are signals of [Hz], 44.056 [kHz] and 44.1 [kHz]. 7. An error correction code adding means for adding an error correction code to the inputted digital signal and supplying the signal added with the error correction code to the QPSK modulating means. The digital signal transmission device according to claim 1, wherein 8. The error correction code adding means includes a data dividing means for dividing the digital signal into a plurality of data according to a predetermined importance of the data contained in the digital signal, and the dividing means. An error correction code adding means for adding a different error correction code to each of the generated data, and an adding means for adding the respective data to which the different error correction code is added. 7. The digital signal transmission device according to item 7. 9. A data dividing means for dividing the digital signal into a plurality of data according to a predetermined importance of the data contained in the digital signal, and one of the divided data. On the other hand, BPSK modulation means for performing roll-off shaping and BPSK modulation, 16QAM modulation means for performing roll-off shaping and 16QAM modulation on one of the divided data, and after the BPSK modulation Data, the 16QAM-modulated data and the QPSK-modulated data are added, and the infrared transmitting means drives the infrared emitter based on the digital modulation signal supplied from the adding means. Infrared is generated by transmitting the infrared signal, and the digital signal is transmitted to an external device. The described digital signal transmission device. 10. A step of receiving a digital signal of a predetermined transmission rate, serial / parallel conversion of the received digital signal to generate an I component signal and a Q component signal, and the I component signal and the Q component signal are generated. Based on the QPSK modulation step for performing the two-phase phase modulation of the I-component signal and the Q-component signal after the roll-off filter processing to narrow the band by the roll-off filter processing and the digital modulation signal obtained by the QPSK modulation step. A digital signal transmitting method, comprising: an infrared transmitting step for transmitting infrared signals to an external device by generating infrared rays by driving an infrared emitter. 11. The roll-off rate of roll-off filter processing in the QPSK modulation step is approximately 20 to 30.
The digital signal transmission method according to claim 10, wherein the digital signal transmission rate is [%]. 12. The digital signal is 32 [kHz], 4
It is a signal with a sampling frequency of 4.056 [kHz], 44.1 [kHz] and / or 48 [kHz]. In the above QPSK modulation step, the above digital signal is
11. The digital signal transmission method according to claim 10, wherein the digital signal transmission is within a frequency band of 3 [MHz] to 6 [MHz]. 13. The first digital signal has a sampling frequency ratio of m: n (m> n, m and n are positive integers).
And a signal of a second sampling frequency, wherein in the QPSK modulation step, the signal of the second sampling frequency is patterned and processed as the signal of the first sampling frequency. 11. The digital signal transmission method according to item 10. 14. The digital signal further comprises signals of third and fourth sampling frequencies whose sampling frequencies are close to each other, and the QPSK modulation step converts the signal of the first sampling frequency. It comprises a first roll-off filter processing step for roll-off shaping and a second roll-off filter processing step for performing roll-off shaping by regarding the signals of the third and fourth sampling frequencies as one sampling frequency. Characterized in that either the processing result in the first roll-off filter processing step or the processing result in the second roll-off filter processing step is selected, and the selected signal is subjected to two-phase phase modulation. The digital signal transmission method according to claim 13. 15. The sampling frequencies of the first, second, third and fourth digital signals are 32 [kHz] and 48, respectively.
15. The digital signal transmission method according to claim 14, wherein the signals are [kHz], 44.056 [kHz] and 44.1 [kHz] signals. 16. An error correction code addition step for adding an error correction code to the received digital signal, wherein the signal to which the error correction code is added is said Q
11. The digital signal transmission method according to claim 10, wherein processing is performed in a PSK modulation step. 17. The error correction code adding step comprises a data division step of dividing the digital signal into a plurality of data according to a predetermined importance of the data included in the digital signal, and the division step. 7. An error correction code addition step for adding a different error correction code to each of the generated data, and an addition step for adding the respective data to which the different error correction code is added. 1
6. The digital signal transmission method according to item 6. 18. A data division step for dividing the digital signal into a plurality of pieces of data according to a predetermined importance of the data contained in the digital signal, and one of the divided pieces of data. On the other hand, a BPSK modulation step for performing roll-off shaping and BPSK modulation, and a 16QAM modulation step for performing roll-off shaping and 16QAM modulation on one of the divided data, and after the BPSK modulation. Data, the data after the 16QAM modulation and the data after the QPSK modulation are added, and the infrared transmitting step drives the infrared emitter based on the digital modulation signal obtained in the adding step. In this way, infrared rays are generated and the above digital signal can be transmitted to an external device. And 10.
The digital signal transmission method described in. 19. A means for serial / parallel converting a digital signal having a predetermined transmission rate to generate an I component signal and a Q component signal, and a filter process for the I component signal and the Q component signal to narrow the band. A roll-off filter having a predetermined roll-off ratio and a means for performing two-phase phase modulation on the I-component signal and the Q-component signal after the filter processing, respectively, and a digital signal supplied from the QPSK modulating means. Infrared transmitting means for generating infrared rays by driving the infrared emitter based on the modulation signal and transmitting the digital signal, and infrared rays transmitted from the infrared transmitting means are received, and a reception signal corresponding to the digital modulation signal is received. And the infrared signal receiving means for forming a digital signal, and demodulating the received signal to reproduce the digital signal. Digital signal receiving apparatus characterized by comprising a regulating unit. 20. The QPSK modulator and the infrared transmitter are provided in a first electronic device, and the infrared receiver and the demodulator are a second electronic device external to the first electronic device. The digital signal transmitting / receiving apparatus according to claim 19, wherein the digital signal transmitting / receiving apparatus is provided in a device. 21. The digital signal transmitting / receiving apparatus according to claim 20, wherein the second electronic device is a speaker device.