WO2023276144A1 - Acoustic communication system and acoustic communication method - Google Patents

Acoustic communication system and acoustic communication method Download PDF

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Publication number
WO2023276144A1
WO2023276144A1 PCT/JP2021/025133 JP2021025133W WO2023276144A1 WO 2023276144 A1 WO2023276144 A1 WO 2023276144A1 JP 2021025133 W JP2021025133 W JP 2021025133W WO 2023276144 A1 WO2023276144 A1 WO 2023276144A1
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acoustic
signal
unit
acoustic signal
communication device
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PCT/JP2021/025133
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French (fr)
Japanese (ja)
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菜々瀬 湯本
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三菱電機株式会社
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Priority to PCT/JP2021/025133 priority Critical patent/WO2023276144A1/en
Publication of WO2023276144A1 publication Critical patent/WO2023276144A1/en

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B11/00—Transmission systems employing sonic, ultrasonic or infrasonic waves

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  • the present disclosure relates to acoustic communication systems and acoustic communication methods.
  • An acoustic communication system that transmits and receives information using sound waves is being considered as one of the methods for realizing a wireless communication system.
  • An acoustic communication system can be constructed by using an acoustic device having an input/output function of an acoustic signal as a communication signal transmitting/receiving device. It is desirable that the frequency characteristics of transmitting and receiving devices in an acoustic communication system be flat. This is because when there is distortion in the frequency characteristics of the transmitting/receiving device, the distortion is superimposed on the communication signal, degrading the demodulation performance of the acoustic communication system. Therefore, when constructing an acoustic communication system using acoustic equipment with uneven frequency characteristics as transmitting/receiving equipment, it is necessary to perform correction processing so that the frequency characteristics become flat.
  • Patent Document 1 presents a method of performing distortion correction processing on a transmission signal using the inverse characteristics of the transmission amplifier characteristics.
  • the present disclosure has been made to solve the above problems, and aims to provide an acoustic communication system and an acoustic communication method capable of improving demodulation performance.
  • the second acoustic signal input unit receives the first acoustic transmission signal and converts the first acoustic transmission signal into a digital signal.
  • the second signal processing unit performs demodulation processing on the second received signal to restore the transmission information;
  • the processing is characterized by using the first precoding coefficient obtained by multiplying the inverse characteristic of the frequency characteristic of the acoustic signal output section by the inverse characteristic of the frequency characteristic of the second acoustic signal input section.
  • An acoustic communication method of the present disclosure includes a first communication device having a first acoustic signal output unit, a first acoustic signal input unit, and a first signal processing unit, a second acoustic signal output unit, a second and a second communicator having a second signal processor, wherein the first signal processor is the second communicator generating a first transmission signal by performing a first precoding process using a first precoding coefficient on transmission information to be transmitted to the first acoustic signal output unit; converting the transmission signal into an analog signal and outputting it as a first acoustic transmission signal; and the second acoustic signal input unit receiving the first acoustic transmission signal and performing the first acoustic transmission generating a second received signal by converting the signal to a digital signal;
  • the second signal processing unit has a step of performing demodulation processing on the second received signal to restore the transmission information, and the first precoding processing includes the first acoustic signal output processing using the first
  • demodulation performance in acoustic communication systems can be improved.
  • FIG. 1 is a block diagram showing the configuration of an acoustic communication system according to Embodiment 1;
  • FIG. 2 is a block diagram showing the configuration of a first signal processing unit of the first communication device shown in FIG. 1;
  • FIG. 2 is a block diagram showing the configuration of a second signal processing unit of the second communication device shown in FIG. 1;
  • FIG. 3 is a diagram showing an example of the hardware configuration of the first communication device shown in FIG. 2;
  • FIG. 4 is a diagram showing an example of a hardware configuration of a second communication device shown in FIG. 3;
  • FIG. 4 is a flowchart showing operations in a calibration mode of the acoustic communication system according to Embodiment 1;
  • Embodiment 1 one-way communication in which the acoustic transmission signal 15 is transmitted from the first communication device 10 to the second communication device 20 and acoustic communication between the first communication device 10 and the second communication device 20 are described. Two-way communication for transmitting and receiving transmission signals 15 and 25 will be described. Note that each of the first and second communication devices 10 and 20 is also called a "transmitter/receiver".
  • the first communication device 10 is, for example, a personal computer (PC) equipped with an external speaker and an external microphone, and operates as a transmitter.
  • the second communication device 20 is, for example, a mobile smart terminal equipped with a speaker and a microphone, and operates as a receiver.
  • a case will be described in which information in a PC is wirelessly transmitted to a smart terminal (for example, a smart phone, a tablet terminal, etc.) using sound.
  • the first communication device 10 outputs the transmission signal 14 generated by the first signal processing unit 11 based on the transmission information from the acoustic signal output unit 12 as the acoustic transmission signal 15, and outputs the second
  • the communication device 20 equalizes the reception signal 26 based on the acoustic transmission signal 15 input from the acoustic signal input section 23 in the second signal processing section 21 and demodulates it to the original transmission information.
  • the equalization process performed by the second signal processing unit 21 aims to reduce the influence of delayed waves received in the propagation path on the acoustic transmission signal 15 output from the first communication device 10.
  • the second communication device 20 sequentially estimates the frequency distortion due to the delayed waves superimposed on the received signal 26 obtained from the acoustic signal input unit 23 each time the signal is received, Correction is desirable.
  • the acoustic signal output unit 12 and the acoustic signal input unit 13 of the first communication device 10 and the acoustic signal output unit 22 and the acoustic signal input unit 23 of the second communication device 20 are It is an acoustic instrument, not calibrated for, and has inherent frequency distortion. Therefore, in communication from the first communication device 10 to the second communication device 20, the received signal 26 based on the acoustic transmission signal 15 received by the acoustic signal input unit 23 of the second communication device 20 has the influence of the propagation path. In addition, the frequency distortion of the acoustic signal output section 12 of the first communication device 10 and the frequency distortion of the acoustic signal input section 23 of the second communication device 20 are superimposed.
  • Frequency distortion is a factor that degrades the demodulation performance of acoustic communication systems, so frequency distortion correction processing is required in acoustic communication systems. It is also possible to estimate and correct the effects of such frequency distortion unique to acoustic equipment through equalization processing in the second communication device 20 . However, when the second communication device 20 estimates and corrects the frequency distortion of the received signal 26 including the influence of the fluctuating delayed wave, the estimation accuracy deteriorates compared to the case of correcting the time-invariant frequency distortion. do. Therefore, it is desirable to separately perform the estimation of the frequency distortion due to the delayed wave, which is a variable value, and the estimation of the frequency distortion, which is a fixed value, unique to the acoustic device.
  • the first signal processing unit 11 corrects the inverse characteristic of the frequency characteristic of the acoustic signal output unit 12 of the first communication device 10 and the second communication
  • a transmission signal 14 whose frequency characteristics have been corrected in advance is generated by performing precoding processing using the inverse characteristics of the frequency characteristics of the acoustic signal input unit 23 of the equipment 20, and the transmission signal 14 is converted into an analog acoustic transmission signal. 15 is output from the acoustic signal output unit 12 to reduce the effect of frequency distortion superimposed on the received signal 26 obtained from the acoustic signal input unit 23 of the second communication device 20.
  • the first communication device 10 and the second communication device 20 know the frequency characteristics of their own equipment, and can read the frequency characteristics of the acoustic equipment stored in the memory or the like at any timing. On the other hand, the first communication device 10 and the second communication device 20 do not know the frequency characteristics of the acoustic equipment of the communication partner, and the first communication device 10 receives the acoustic signal input from the second communication device 20. 23 frequency characteristics must be obtained.
  • the second communication device 20 before performing data communication from the first communication device 10 to the second communication device 20, transmits the frequency characteristics of the acoustic signal input unit 23 to the first communication device 10, and performs calibration settings in advance for the purpose of calculating precoding coefficients for correction in the first communication device 10. .
  • the operation mode of the acoustic communication system according to Embodiment 1 consists of a calibration mode in which precoding coefficients for correction are calculated and a data communication mode in which normal data communication is performed.
  • the calibration mode is selected, and the exchange of acoustic signals by two-way communication between the first communication device 10 and the second communication device 20 causes the first communication device 10 to , the frequency characteristics of the acoustic signal input unit 23 of the second communication device 20 are obtained, and the precoding coefficients are calculated.
  • FIG. 2 is a block diagram showing the configuration of the first signal processing section 11 of the first communication device 10.
  • the first signal processing unit 11 of the first communication device 10 includes a calibration data generation unit 101 that generates predetermined calibration data (generally, calibration data with uniform frequency band characteristics), and a data A transmission information generation unit 102 that generates transmission information to be transmitted in the communication mode, a switching unit 103 that outputs either calibration data or transmission information to a precoding processing unit, and a precoding unit for the output of the switching unit 103. It has a precoding processing unit 104 that performs coding processing and a precoding coefficient calculation unit 105 that calculates coefficients in the precoding processing.
  • the first signal processing unit 11 also includes a post-coding processing unit 106 that performs post-coding processing on the received signal 16 obtained from the acoustic signal input unit 13, and a post-coding coefficient that calculates coefficients in the post-coding processing. It has a calculating section 107 and a frequency characteristic estimating section 108 for estimating the frequency characteristic of the output signal from the postcoding processing section 106 . In addition, the first signal processing unit 11 has a frequency characteristic memory 109 in which writing from the frequency characteristic estimating unit 108 and reading to the precoding coefficient calculating unit 105 and the postcoding coefficient calculating unit 107 are possible. .
  • the frequency characteristic memory 109 stores the frequency characteristic of the acoustic signal output section 12 and the frequency characteristic of the acoustic signal input section 13 in advance.
  • the first signal processing section 11 of the first communication device 10 controls the signal processing operation in each mode according to the operation control signal.
  • FIG. 3 is a block diagram showing the configuration of the second signal processing section 21.
  • the second signal processing unit 21 includes a calibration data generation unit 201 that generates calibration data with uniform frequency band characteristics, a precoding processing unit 202 that performs precoding processing on the calibration data, and a precoding processing unit 202 that performs precoding processing on the calibration data. and a precoding coefficient calculation unit 203 for calculating coefficients in the coding process.
  • the second signal processing unit 21 includes a connection destination selection unit 204 that determines the connection destination of the received signal 26 obtained from the acoustic signal input unit 23, and when the connection destination selection unit 204 selects the connection destination, A postcoding processing unit 205 that performs postcoding processing on a transmission signal, a postcoding coefficient calculation unit 206 that calculates coefficients in the postcoding processing, and a frequency characteristic that estimates the frequency characteristics of the output signal of the postcoding processing unit 205.
  • the second signal processing unit 21 has a frequency characteristic memory 211 in which data can be written from the frequency characteristic estimation unit 207 and read out to the precoding coefficient calculation unit 203 and the postcoding coefficient calculation unit 206. .
  • the frequency characteristic memory 211 stores the frequency characteristic of the acoustic signal output section 22 and the frequency characteristic of the acoustic signal input section 23 in advance.
  • the second signal processing section 21 controls the signal processing operation in each mode according to the operation control signal.
  • FIG. 4 is a diagram showing an example of the hardware configuration of the first communication device 10 shown in FIG.
  • the first communication device 10 includes a processor 151 such as a CPU (Central Processing Unit), a memory 152 that is a volatile storage device, a hard disk drive (HDD) or solid state drive (SSD). ), an acoustic signal output section 12 comprising a digital-to-analog converter 154 and a speaker 155, and an acoustic signal input section 13 comprising an analog-to-digital converter 156 and a microphone 157.
  • the memory 152 is, for example, a volatile semiconductor memory such as RAM (Random Access Memory).
  • the processing circuitry may be dedicated hardware or processor 151 executing programs stored in memory 152 .
  • the processor 151 may be any of a processing device, an arithmetic device, a microprocessor, a microcomputer, and a DSP (Digital Signal Processor).
  • the motion control signals shown in FIG. 2 are generated by processor 151, for example.
  • the processing circuit may be, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array) ), or a combination of any of these.
  • an acoustic communication program for performing acoustic communication is implemented by software, firmware, or a combination of software and firmware.
  • Software and firmware are written as programs and stored in memory 152 .
  • the processor 151 implements the functions of the units shown in FIG. 2 by reading and executing programs stored in the memory 152 .
  • FIG. 5 is a diagram showing an example of the hardware configuration of the second communication device 20 shown in FIG.
  • the second communication device 20 includes a processor 251 such as a CPU, a memory 252 which is a volatile storage device, a nonvolatile storage device 253 such as an HDD or SSD, and a digital-to-analog converter. It has an acoustic signal output section 22 consisting of a device 254 and a speaker 255 and an acoustic signal input section 23 consisting of an analog-to-digital converter 256 and a microphone 257 .
  • Memory 252 is, for example, a volatile semiconductor memory such as RAM.
  • Each function of the second signal processing section 21 of the second communication device 20 is realized by a processing circuit.
  • the processing circuitry may be dedicated hardware or processor 251 executing programs stored in memory 252 .
  • Processor 251 may be any of a processing unit, an arithmetic unit, a microprocessor, a microcomputer, and a DSP.
  • the motion control signals shown in FIG. 3 are generated by processor 251, for example.
  • the processing circuitry may be, for example, a single circuit, multiple circuits, programmed processors, parallel programmed processors, ASICs, FPGAs, or any combination thereof.
  • the processing circuit is the processor 151
  • an acoustic communication program for performing acoustic communication is implemented by software, firmware, or a combination of software and firmware.
  • Software and firmware are written as programs and stored in memory 252 .
  • the processor 251 implements the functions of the units shown in FIG. 2 by reading and executing programs stored in the memory 252 .
  • the second signal processing unit 21 of the second communication device 20 may be partially realized by dedicated hardware and partially realized by software or firmware. As such, the processing circuitry may implement each of the functions described above in hardware, software, firmware, or any combination thereof.
  • FIG. 6 is a flow chart showing the operation in the calibration mode of the acoustic communication system according to the first embodiment.
  • this acoustic communication system allows the second communication device 20 to move. It is desirable that the communicator 10 and the second communicator 20 not move.
  • the first communication device 10 uses the output of the switching unit 103 as the output signal from the calibration data generation unit 101, and then generates the calibration data in the calibration data generation step S101. Generate.
  • the first communication device 10 reads out the frequency characteristic (TS) of the acoustic signal output unit 12 from the frequency characteristic memory 109, and reads the frequency characteristic (TS) of the acoustic signal output unit 12.
  • TS frequency characteristic
  • TS frequency characteristic of the acoustic signal output unit 12.
  • the first communication device 10 precodes the calibration data using the inverse characteristic (1/TS) calculated in precoding coefficient calculation step S102 as a precoding coefficient. Take action.
  • the first communication device 10 outputs the transmission signal 14 obtained by performing these processes as the acoustic transmission signal 15 from the acoustic signal output unit 12 .
  • the transmission signal 14 is affected by the frequency distortion of the acoustic signal output section 12 when passing through the acoustic signal output section 12. Since it is corrected by the inverse characteristic (1/TS), the frequency characteristic of the acoustic transmission signal 15 is flat.
  • postcoding processing step S105 the second communication device 20 performs postcoding processing on the received signal 26 obtained from the acoustic signal input unit 23 using the postcoding coefficients calculated in the postcoding coefficient calculation step S104. to implement.
  • the second communication device 20 estimates the frequency characteristic of the output from the postcoding processing unit 205, and stores the estimated frequency characteristic in the temporary memory in the frequency characteristic memory 211.
  • the frequency characteristic stored in the temporary memory is It can be regarded as a propagation path characteristic (H) that is not affected by frequency distortion of the acoustic signal output section 12 of the first communication device 10 and the acoustic signal input section 23 of the second communication device 20 .
  • the second communication device 20 reads the frequency characteristic (H) stored in the temporary memory of the frequency characteristic memory 211 and the frequency characteristic (RS) of the acoustic signal output unit 22, An inverse characteristic (1/(H ⁇ RS)) of a value (H ⁇ RS) obtained by multiplying these frequency characteristics is set as a precoding coefficient. Then, the second communication device 20 further reads the frequency characteristic (RM) of the acoustic signal input section 23 from the frequency characteristic memory 211 and multiplies it by (1/(H ⁇ RS)).
  • the second communication device 20 newly generates calibration data in the calibration data generation step S108.
  • the generated calibration data series is the same series as the calibration signal generated in the calibration data generation step S101.
  • precoding processing step S109 the second communication device 20 precodes the generated calibration data using the precoding coefficients (RM/(H ⁇ RS)) calculated in precoding coefficient calculation step S107. Take action.
  • the second communication device 20 outputs the precoded calibration data as an acoustic transmission signal 25 from the acoustic signal output unit 22, and the first communication device 10 outputs the acoustic transmission signal 25 from the acoustic signal input unit 13.
  • Received as received signal 16 the frequency characteristic (RM) of the acoustic signal input section 23 of the second communication device 20 and the first The influence of the frequency characteristic (TM) of the acoustic signal input section 13 of the communication device 10 remains.
  • the first communication device 10 reads the frequency characteristic (TM) of the acoustic signal input unit 13 from the frequency characteristic memory 109, and sets the inverse characteristic (1/TM) as the postcoding coefficient. do.
  • postcoding processing step S111 the first communication device 10 performs postcoding processing on the received signal 16 obtained from the acoustic signal input unit 13 using the postcoding coefficients. The influence of the frequency characteristic (RM) of the acoustic signal input section 23 of the second communication device 20 remains in the signal after this postcoding process.
  • the first communication device 10 estimates the frequency characteristic of the post-coding signal, regards the estimation result as the frequency characteristic of the acoustic signal input unit 23, and stores it in the frequency characteristic memory 109. .
  • the precoding coefficient calculation step S113 the first communication device 10 reads the frequency characteristics (RM) of the acoustic signal input section 23 and the frequency characteristics (TS) of the acoustic signal output section 12 from the frequency characteristic memory 109. , and a value (1/(RM ⁇ TS)) multiplied by its inverse characteristic is set as a precoding coefficient.
  • the acoustic communication system assumes that the calibration mode is completed, and shifts to the data communication mode.
  • the first communication device 10 switches the output of the switching unit 103 to the output of the transmission information generation unit 102, and then uses the precoding coefficients set in the precoding coefficient calculation step S113 to generate transmission information. , and is output as an acoustic transmission signal 15 from the acoustic signal output unit 12 .
  • the second communication device 20 sets the connection destination of the connection destination selection unit 204 to the propagation path characteristic estimation unit 208, calculates the propagation path characteristics of the received signal 26 obtained from the acoustic signal input unit 23, After the equalization processing section 209 performs equalization processing using the propagation path characteristics estimation value, the demodulation section 210 performs demodulation processing to generate the original transmission information.
  • the first signal processing unit 11a of the first communication device of Modification 1 reads out from the time-diversity data memory 122 storing a plurality of acoustic transmission signals 25 and the time-diversity data memory. It further has a time diversity processing unit 121 for averaging the plurality of acoustic transmission signals 25 after synchronizing them in time.
  • the acoustic communication system according to Modification 1 is the same as that shown in FIGS.
  • Noise enhancement can occur in the first communication device in the postcoding processing step S111 in FIG.
  • White noise superimposed on the acoustic transmission signal 25 causes noise enhancement. Therefore, before performing the postcoding processing step S111, the second communication device 20 transmits the acoustic transmission signal 25 a plurality of times, and the first communication device receives a plurality of The received signal 16 is stored in the time diversity data memory, and then the signal read out from the time diversity data memory 122 is averaged by the diversity processing unit 121 and transferred to the postcoding processing unit 106 .
  • FIG. 8 is a block diagram showing the configuration of the first signal processing section 11b of the first communication device of the acoustic communication system according to Modification 2 of Embodiment 1.
  • the first signal processing unit 11b has an interference wave power measurement unit 131 and an interference wave power memory 132, and the details of the processing performed by the frequency characteristic estimation unit 108a are as follows: It differs from the acoustic communication system shown in FIGS.
  • This processing can improve the accuracy of estimating the frequency characteristics of the acoustic transmission signal 25 transmitted in an environment where interference waves occur.
  • the second communication device 20 which is the receiver, is a smart terminal. It is also possible to replace it with a smart terminal.
  • the multiple candidate communication devices that can be the second communication device 20, and the multiple candidate communication devices may have different model codes.
  • smart terminals may have different frequency characteristics of acoustic equipment for each model and individual, so it is necessary to switch the operation mode of the acoustic communication system to the calibration mode again. Therefore, when there are a plurality of models as candidates for the second communication device, in FIG. An example will be described in which the model code and the precoding coefficient are stored in association with each other.
  • the precoding coefficients associated with the model code of the second communication device 20 exist in the precoding coefficient memory 142, the operation in the calibration mode is skipped, and the read precoding coefficients are stored in the data communication mode. It may be set as a precoding coefficient.
  • Embodiment 2 ⁇ 2-1>> Configuration
  • the first and second communication devices 10 and 20 which are transceivers, have known frequency characteristics of their own acoustic devices.
  • the second communication device 20 is a smart terminal, the frequency characteristics of the acoustic signal output section and the acoustic signal input section of the smart terminal itself are not necessarily disclosed, so the above assumption does not hold. There can be cases.
  • the second communication device 30 when the second communication device 30 used as a receiver cannot acquire the frequency characteristics of its own acoustic equipment, the second communication device 30 A method of transmitting the frequency characteristic of the acoustic signal input unit 23 of the second communication device 30 to the communication device 10 and calculating the precoding coefficients for correction in the first communication device 10 will be described.
  • FIG. 10 is a block diagram showing the configuration of the acoustic communication system according to the second embodiment.
  • the same reference numerals as those shown in FIG. 1 are attached to the same or corresponding configurations as those shown in FIG.
  • the acoustic communication system according to the second embodiment differs from the acoustic communication system according to the embodiment in the configuration and operation of the second communication device 30.
  • FIG. 10 is a block diagram showing the configuration of the acoustic communication system according to the second embodiment.
  • the same reference numerals as those shown in FIG. 1 are attached to the same or corresponding configurations as those shown in FIG.
  • the acoustic communication system according to the second embodiment differs from the acoustic communication system according to the embodiment in the configuration and operation of the second communication device 30.
  • FIG. 11 is a block diagram showing the configuration of the second signal processing section 31 of the second communication device 30 of the acoustic communication system according to the second embodiment.
  • the second signal processing unit 31 of the second communication device 30 includes a calibration data generation unit 501 that generates calibration data with uniform frequency band characteristics, and a reception signal 26 obtained from the acoustic signal input unit 23.
  • a connection destination selection unit 502 that determines a connection destination, a propagation path characteristics estimation unit 503 that calculates the propagation path characteristics of the transmission signal 14 when the connection destination selection unit 502 selects the connection destination, and the estimated propagation path characteristics.
  • a demodulation unit 505 for demodulating the equalized signal.
  • FIG. 12 is a flow chart showing the operation of the calibration mode according to the second embodiment.
  • the second communication device 30 in order to minimize the influence of the propagation path characteristics during the calibration mode, the second communication device 30 is fixed at a position immediately in front of the first communication device 10 as shown in FIG. Treatment is desirable.
  • the first communication device 10 reads out the frequency characteristic (TM) of the acoustic signal input unit 13 from the frequency characteristic memory 109 in a postcoding coefficient calculation step S202, and uses its inverse characteristic (1/TM) as a precoding coefficient. set to Then, in postcoding processing step S203, postcoding processing is performed on the received signal 16 obtained from the acoustic signal input unit 13 using the postcoding coefficients calculated in the postcoding coefficient calculation step S202. This processing corrects the frequency distortion of the acoustic signal input section 13 superimposed when the received signal 16 passes through the acoustic signal input section 13, and the frequency characteristic of the signal after the postcoding process is the same as that of the acoustic signal output section 22. It becomes a frequency characteristic (RS). After that, the first communication device 10 estimates the frequency characteristic of the signal after postcoding in the frequency characteristic estimation step S204, and stores the estimation result in the temporary memory.
  • TM frequency characteristic
  • RS frequency characteristic
  • the first communication device 10 uses the output of the switching unit 103 as the output signal from the calibration data generation unit 101, and then generates calibration data in the calibration data generation step S205.
  • precoding coefficient calculation step S206 the frequency characteristic (TS) of the acoustic signal output unit 12 and the frequency characteristic (RS) stored in the temporary memory are read out from the frequency characteristic memory 109, and the frequency characteristic obtained by multiplying both characteristics is obtained.
  • the inverse characteristic (1/(TS ⁇ RS)) be the precoding coefficient.
  • precoding processing step S207 precoding processing using the coefficients calculated in precoding coefficient calculation step S206 is performed on the calibration data.
  • the first communication device 10 outputs the transmission signal 14 subjected to these processes as an acoustic transmission signal 15 from the acoustic signal output unit 12 .
  • the inverse characteristic (1/RS) of the frequency distortion of the acoustic signal output section 22 is given to the frequency characteristic of the output acoustic transmission signal 15 .
  • the second communication device 30 sets the connection destination of the connection destination selection unit 502 to the data memory 506 , receives the acoustic transmission signal 15 with the microphone 23 , and stores the reception signal 26 in the data memory 506 . Then, the output of the switching unit 507 is used as the readout signal from the data memory, and the readout signal is output as the acoustic transmission signal 25 from the acoustic signal output unit 22 . As a result of these processes, the acoustic transmission signal 15 output by the first communication device 10 is returned via the acoustic signal input section 23 and the acoustic signal output section 22 of the second communication device 30.
  • the frequency characteristic (RM) of the microphone 23 is superimposed on the frequency characteristic of the acoustic transmission signal 25 .
  • the first communication device 10 reads out the frequency characteristic (TM) of the acoustic signal input unit 13 from the frequency characteristic memory 109, and uses the inverse characteristic (1/TM) as the postcoding coefficient. set as In post-coding processing step S209, the received signal 16 obtained from the acoustic signal input unit 13 is subjected to post-coding processing. By this processing, the influence of the frequency characteristic (RM) of the acoustic signal input section 23 remains in the signal after the postcoding processing.
  • the first communication device 10 estimates the frequency characteristics of the post-coding signal in a frequency characteristics step S210, regards the estimation results as the frequency characteristics of the acoustic signal input unit 23, and stores them in the frequency characteristics memory 109. do.
  • the first communication device 10 reads the frequency characteristics (RM) of the acoustic signal input section 23 and the frequency characteristics (TS) of the acoustic signal output section 12 from the frequency characteristic memory 109. , and a value (1/(RM ⁇ TS)) multiplied by its inverse characteristic is set as a precoding coefficient.
  • the acoustic communication system assumes that the calibration mode is completed, and shifts to the data communication mode. After that, data communication is performed in the same manner as in the first embodiment.
  • the frequency distortion of the acoustic signal output unit 22 is calculated with respect to the calibration data after the first communication device 10 knows the frequency characteristics of the acoustic signal output unit 22. is corrected, the influence of the frequency distortion of the acoustic signal output unit 22 in the calibration data passed through the acoustic signal output unit 22 and the acoustic signal input unit 23 is corrected, and the first communication device 10 Only the frequency characteristic of the acoustic signal input section 23 can be transmitted to the .
  • the first communication device 10 can reproduce the sound of the second communication device 30.
  • the frequency characteristics of the signal input unit 23 can be correctly estimated and reflected in the precoding coefficients. Therefore, it is possible to improve the demodulation performance in the acoustic communication system during data communication.
  • Embodiment 2 also in Embodiment 2, the method for reducing the influence of noise enhancement described in Modifications 1 to 3 of Embodiment 1, and the influence of interference waves are reduced. It is also possible to implement a method of linking and storing model codes and precoding coefficients when the second communication device 20 is a plurality of candidates.

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Abstract

This acoustic communication system comprises: a first communication device (10) having a first acoustic signal output unit (12), a first acoustic signal input unit (13), and a first signal processing unit (11); and a second communication device (20) having a second acoustic signal output unit (22), a second acoustic signal input unit (23), and a second signal processing unit (21), wherein the first signal processing unit performs a first precoding process on transmission information by using a first precoding coefficient to generate a first transmission signal (14), the first acoustic signal output unit outputs a first acoustic transmission signal (15), the second acoustic signal input unit generates a second received signal (26) based on the first acoustic transmission signal, the second signal processing unit restores transmission information from the second received signal, and the first precoding process uses a first precoding coefficient (1/(TS×RM)) based on the inverse characteristic (1/TS) of the frequency characteristic of the first acoustic signal output unit and the inverse characteristic (1/RM) of the frequency characteristic of the second acoustic signal input unit.

Description

音響通信システム及び音響通信方法Acoustic communication system and acoustic communication method
　本開示は、音響通信システム及び音響通信方法に関する。 The present disclosure relates to acoustic communication systems and acoustic communication methods.
　無線通信システムの実現方式の一つとして、音波にて情報の送受を行う音響通信システムが検討されている。音響通信システムは、音響信号の入出力機能を備えた音響機器を通信用信号の送受信機器として使用することで構築することができる。音響通信システムにおける送受信機器の周波数特性は、平坦であることが望ましい。これは、送受信機器の周波数特性に歪が存在する場合、通信用信号に歪が重畳され、音響通信システムの復調性能が劣化するためである。そのため、周波数特性が平坦でない音響機器を送受信機器として音響通信システムを構築する場合、周波数特性が平坦になるように補正処理を行う必要がある。 An acoustic communication system that transmits and receives information using sound waves is being considered as one of the methods for realizing a wireless communication system. An acoustic communication system can be constructed by using an acoustic device having an input/output function of an acoustic signal as a communication signal transmitting/receiving device. It is desirable that the frequency characteristics of transmitting and receiving devices in an acoustic communication system be flat. This is because when there is distortion in the frequency characteristics of the transmitting/receiving device, the distortion is superimposed on the communication signal, degrading the demodulation performance of the acoustic communication system. Therefore, when constructing an acoustic communication system using acoustic equipment with uneven frequency characteristics as transmitting/receiving equipment, it is necessary to perform correction processing so that the frequency characteristics become flat.
　例えば、特許文献１は、送信信号に対して、送信アンプの特性の逆特性を用いて歪補正処理を実施する方法を提示している。 For example, Patent Document 1 presents a method of performing distortion correction processing on a transmission signal using the inverse characteristics of the transmission amplifier characteristics.
特開２０２０－１７８８４号公報JP 2020-17884 A
　しかし、特許文献１の方法は、受信機における周波数歪の補正処理を提示していない。したがって、このような方法を用いても、音響機器を送受信機として用いる音響通信システムにおける周波数歪を適切に補正することはできず、高い復調性能を得ることができない。 However, the method of Patent Document 1 does not present frequency distortion correction processing in the receiver. Therefore, even if such a method is used, it is not possible to appropriately correct frequency distortion in an acoustic communication system using acoustic devices as transmitters and receivers, and high demodulation performance cannot be obtained.
　本開示は、上記課題を解決するためになされたものであり、復調性能を向上させることができる音響通信システム及び音響通信方法を提供することを目的としている。 The present disclosure has been made to solve the above problems, and aims to provide an acoustic communication system and an acoustic communication method capable of improving demodulation performance.
　本開示の音響通信システムは、第１の音響信号出力部、第１の音響信号入力部、及び第１の信号処理部を有する第１の通信機と、第２の音響信号出力部、第２の音響信号入力部、及び第２の信号処理部を有する第２の通信機と、を有し、前記第１の信号処理部は、前記第２の通信機に送信する送信情報に対して第１のプリコーディング係数を用いて第１のプリコーディング処理を行なって第１の送信信号を生成し、前記第１の音響信号出力部は、デジタル信号である前記第１の送信信号をアナログ信号に変換した上で第１の音響送信信号として出力し、前記第２の音響信号入力部は、前記第１の音響送信信号を受信し、前記第１の音響送信信号をデジタル信号に変換することで第２の受信信号を生成し、前記第２の信号処理部は、前記第２の受信信号に復調処理を施して前記送信情報を復元し、前記第１のプリコーディング処理は、前記第１の音響信号出力部の周波数特性の逆特性と前記第２の音響信号入力部の周波数特性の逆特性とを乗算した前記第１のプリコーディング係数を用いた処理であることを特徴とする。 An acoustic communication system of the present disclosure includes a first communication device having a first acoustic signal output unit, a first acoustic signal input unit, and a first signal processing unit, a second acoustic signal output unit, a second and a second communication device having an acoustic signal input unit and a second signal processing unit, wherein the first signal processing unit performs a second processing on transmission information to be transmitted to the second communication device A first precoding process is performed using a precoding coefficient of 1 to generate a first transmission signal, and the first acoustic signal output unit converts the first transmission signal, which is a digital signal, into an analog signal. After converting, it is output as a first acoustic transmission signal, and the second acoustic signal input unit receives the first acoustic transmission signal and converts the first acoustic transmission signal into a digital signal. generating a second received signal, wherein the second signal processing unit performs demodulation processing on the second received signal to restore the transmission information; The processing is characterized by using the first precoding coefficient obtained by multiplying the inverse characteristic of the frequency characteristic of the acoustic signal output section by the inverse characteristic of the frequency characteristic of the second acoustic signal input section.
　本開示の音響通信方法は、第１の音響信号出力部、第１の音響信号入力部、及び第１の信号処理部を有する第１の通信機と、第２の音響信号出力部、第２の音響信号入力部、及び第２の信号処理部を有する第２の通信機と、を有する音響通信システムが実施する方法であって、前記第１の信号処理部が、前記第２の通信機に送信する送信情報に対して第１のプリコーディング係数を用いて第１のプリコーディング処理を行なって第１の送信信号を生成するステップと、前記第１の音響信号出力部が、前記第１の送信信号をアナログ信号に変換した上で第１の音響送信信号として出力するステップと、前記第２の音響信号入力部が、前記第１の音響送信信号を受信し、前記第１の音響送信信号をデジタル信号に変換することで第２の受信信号を生成するステップと、
　前記第２の信号処理部が、前記第２の受信信号に復調処理を施して前記送信情報を復元するステップと、を有し、前記第１のプリコーディング処理は、前記第１の音響信号出力部の周波数特性の逆特性と前記第２の音響信号入力部の周波数特性の逆特性とを乗算した前記第１のプリコーディング係数を用いた処理であることを特徴とする。 An acoustic communication method of the present disclosure includes a first communication device having a first acoustic signal output unit, a first acoustic signal input unit, and a first signal processing unit, a second acoustic signal output unit, a second and a second communicator having a second signal processor, wherein the first signal processor is the second communicator generating a first transmission signal by performing a first precoding process using a first precoding coefficient on transmission information to be transmitted to the first acoustic signal output unit; converting the transmission signal into an analog signal and outputting it as a first acoustic transmission signal; and the second acoustic signal input unit receiving the first acoustic transmission signal and performing the first acoustic transmission generating a second received signal by converting the signal to a digital signal;
The second signal processing unit has a step of performing demodulation processing on the second received signal to restore the transmission information, and the first precoding processing includes the first acoustic signal output processing using the first precoding coefficient obtained by multiplying the inverse characteristic of the frequency characteristic of the input section by the inverse characteristic of the frequency characteristic of the second acoustic signal input section.
　本開示によれば、音響通信システムにおける復調性能を向上させることができる。 According to the present disclosure, demodulation performance in acoustic communication systems can be improved.
実施の形態１に係る音響通信システムの構成を示すブロック図である。1 is a block diagram showing the configuration of an acoustic communication system according to Embodiment 1; FIG. 図１に示される第１の通信機の第１の信号処理部の構成を示すブロック図である。2 is a block diagram showing the configuration of a first signal processing unit of the first communication device shown in FIG. 1; FIG. 図１に示される第２の通信機の第２の信号処理部の構成を示すブロック図である。2 is a block diagram showing the configuration of a second signal processing unit of the second communication device shown in FIG. 1; FIG. 図２に示される第１の通信機のハードウェア構成の例を示す図である。3 is a diagram showing an example of the hardware configuration of the first communication device shown in FIG. 2; FIG. 図３に示される第２の通信機のハードウェア構成の例を示す図である。4 is a diagram showing an example of a hardware configuration of a second communication device shown in FIG. 3; FIG. 実施の形態１に係る音響通信システムのキャリブレーションモードの動作を示すフローチャートである。4 is a flowchart showing operations in a calibration mode of the acoustic communication system according to Embodiment 1; 実施の形態１の変形例１に係る音響通信システムの第１の通信機の第１の信号処理部の構成を示すブロック図である。FIG. 10 is a block diagram showing the configuration of the first signal processing unit of the first communication device of the acoustic communication system according to Modification 1 of Embodiment 1; 実施の形態１の変形例２に係る音響通信システムの第１の通信機の第１の信号処理部の構成を示すブロック図である。FIG. 10 is a block diagram showing the configuration of the first signal processing unit of the first communication device of the acoustic communication system according to Modification 2 of Embodiment 1; 実施の形態１の変形例３に係る音響通信システムの第１の通信機の第１の信号処理部の構成を示すブロック図である。FIG. 12 is a block diagram showing the configuration of the first signal processing unit of the first communication device of the acoustic communication system according to Modification 3 of Embodiment 1; 実施の形態２に係る音響通信システムの構成を示すブロック図である。2 is a block diagram showing the configuration of an acoustic communication system according to Embodiment 2; FIG. 実施の形態２に係る音響通信システムの第２の通信機の構成を示すブロック図である。FIG. 9 is a block diagram showing the configuration of a second communication device of the acoustic communication system according to Embodiment 2; 実施の形態２に係る音響通信システムのキャリブレーションモードの動作を示すフローチャートである。9 is a flowchart showing operations in a calibration mode of the acoustic communication system according to Embodiment 2;
　以下に、実施の形態に係る音響通信システム及び音響通信方法を、図面を参照しながら説明する。以下の実施の形態は、例にすぎず、実施の形態を適宜組み合わせること及び各実施の形態を適宜変更することが可能である。 An acoustic communication system and an acoustic communication method according to embodiments will be described below with reference to the drawings. The following embodiments are merely examples, and the embodiments can be combined as appropriate and each embodiment can be modified as appropriate.
《１》実施の形態１
《１－１》構成
　図１は、実施の形態１に係る音響通信システムの構成を示すブロック図である。図１に示される音響通信システムは、第１の通信機１０及び第２の通信機２０を有し、これらの間で音波である音響送信信号を送受信する。第１の通信機１０は、第１の信号処理部１１、音響信号出力部（「第１の音声信号出力部」ともいう。）１２、及び音響信号入力部（「第１の音声信号入力部」ともいう。）１３を有している。第２の通信機２０は、第２の信号処理部２１、音響信号出力部（「第２の音声信号出力部」ともいう。）２２、及び音響信号入力部（「第２の音声信号入力部」ともいう。）２３を有している。音響信号出力部１２は、例えば、デジタルアナログ変換器とスピーカとを有する。音響信号入力部１３は、例えば、アナログデジタル変換器とマイクとを有するマイク。また、音響信号出力部２２は、例えば、デジタルアナログ変換器とスピーカとを有する。音響信号入力部２３は、例えば、アナログデジタル変換器とマイクとを有する。実施の形態１では、第１の通信機１０から第２の通信機２０へ音響送信信号１５を送信する片方向通信と、第１の通信機１０と第２の通信機２０との間で音響送信信号１５、２５を送受信する双方向通信とを説明する。なお、第１及び第２の通信機１０、２０のそれぞれは、「送受信機」とも呼ばれる。 <<1>> Embodiment 1
<<1-1>> Configuration FIG. 1 is a block diagram showing the configuration of the acoustic communication system according to the first embodiment. The acoustic communication system shown in FIG. 1 has a first communicator 10 and a second communicator 20 for transmitting and receiving acoustic transmission signals, which are sound waves, therebetween. The first communication device 10 includes a first signal processing unit 11, an acoustic signal output unit (also referred to as "first audio signal output unit") 12, and an acoustic signal input unit ("first audio signal input unit ) 13. The second communication device 20 includes a second signal processing unit 21, an acoustic signal output unit (also referred to as “second audio signal output unit”) 22, and an acoustic signal input unit (“second audio signal input unit”). ”). The acoustic signal output unit 12 has, for example, a digital-analog converter and a speaker. The acoustic signal input unit 13 is, for example, a microphone having an analog-to-digital converter and a microphone. Also, the acoustic signal output unit 22 has, for example, a digital-analog converter and a speaker. The acoustic signal input section 23 has, for example, an analog-to-digital converter and a microphone. In Embodiment 1, one-way communication in which the acoustic transmission signal 15 is transmitted from the first communication device 10 to the second communication device 20 and acoustic communication between the first communication device 10 and the second communication device 20 are described. Two-way communication for transmitting and receiving transmission signals 15 and 25 will be described. Note that each of the first and second communication devices 10 and 20 is also called a "transmitter/receiver".
　実施の形態１では、第１の通信機１０は、例えば、外付けのスピーカと外付けのマイクとを備えたパーソナルコンピュータ（ＰＣ）であり、送信機として動作する。また、第２の通信機２０は、例えば、スピーカとマイクとを備えた移動可能なスマート端末であり、受信機として動作する。実施の形態１では、ＰＣ内の情報をスマート端末（例えば、スマートフォン、タブレット端末など）に、音響によって無線伝送するケースを説明する。 In Embodiment 1, the first communication device 10 is, for example, a personal computer (PC) equipped with an external speaker and an external microphone, and operates as a transmitter. Also, the second communication device 20 is, for example, a mobile smart terminal equipped with a speaker and a microphone, and operates as a receiver. In Embodiment 1, a case will be described in which information in a PC is wirelessly transmitted to a smart terminal (for example, a smart phone, a tablet terminal, etc.) using sound.
　実施の形態１では、第１の通信機１０は、送信情報に基づいて第１の信号処理部１１で生成された送信信号１４を音響信号出力部１２から音響送信信号１５として出力し、第２の通信機２０は、音響信号入力部２３から入力された音響送信信号１５に基づく受信信号２６を第２の信号処理部２１にて等化処理して元の送信情報へと復調する。第２の信号処理部２１によって実施される等化処理は、第１の通信機１０から出力された音響送信信号１５が伝搬路にて受ける遅延波の影響を低減することを目的としており、第２の通信機２０が移動する場合には、時変となる遅延波に対応する必要がある。遅延波の影響は周波数歪として現れるため、第２の通信機２０は、音響信号入力部２３から得た受信信号２６に重畳される遅延波による周波数歪を、信号受信の度に逐次推定し、補正することが望ましい。 In Embodiment 1, the first communication device 10 outputs the transmission signal 14 generated by the first signal processing unit 11 based on the transmission information from the acoustic signal output unit 12 as the acoustic transmission signal 15, and outputs the second The communication device 20 equalizes the reception signal 26 based on the acoustic transmission signal 15 input from the acoustic signal input section 23 in the second signal processing section 21 and demodulates it to the original transmission information. The equalization process performed by the second signal processing unit 21 aims to reduce the influence of delayed waves received in the propagation path on the acoustic transmission signal 15 output from the first communication device 10. When two communication devices 20 move, it is necessary to deal with delayed waves that change with time. Since the effect of the delayed waves appears as frequency distortion, the second communication device 20 sequentially estimates the frequency distortion due to the delayed waves superimposed on the received signal 26 obtained from the acoustic signal input unit 23 each time the signal is received, Correction is desirable.
　また、実施の形態１では、第１の通信機１０の音響信号出力部１２及び音響信号入力部１３と、第２の通信機２０の音響信号出力部２２及び音響信号入力部２３とは、通信用に校正されたものでなく、音響機器であり、固有の周波数歪を有している。そのため、第１の通信機１０から第２の通信機２０への通信において、第２の通信機２０の音響信号入力部２３が受け取る音響送信信号１５に基づく受信信号２６には、伝搬路の影響に加えて第１の通信機１０の音響信号出力部１２の周波数歪及び第２の通信機２０の音響信号入力部２３の周波数歪が重畳されている。 Further, in Embodiment 1, the acoustic signal output unit 12 and the acoustic signal input unit 13 of the first communication device 10 and the acoustic signal output unit 22 and the acoustic signal input unit 23 of the second communication device 20 are It is an acoustic instrument, not calibrated for, and has inherent frequency distortion. Therefore, in communication from the first communication device 10 to the second communication device 20, the received signal 26 based on the acoustic transmission signal 15 received by the acoustic signal input unit 23 of the second communication device 20 has the influence of the propagation path. In addition, the frequency distortion of the acoustic signal output section 12 of the first communication device 10 and the frequency distortion of the acoustic signal input section 23 of the second communication device 20 are superimposed.
　周波数歪は、音響通信システムの復調性能の劣化要因となるため、音響通信システムでは、周波数歪の補正処理の実施が求められる。このような音響機器に固有の周波数歪の影響は、第２の通信機２０における等化処理にて推定及び補正することも可能である。しかし、第２の通信機２０で、変動する遅延波の影響を含めて受信信号２６の周波数歪を推定及び補正する場合、時不変の周波数歪を補正する場合と比較して、推定精度が劣化する。このため、変動値である遅延波による周波数歪の推定と固定値である音響機器に固有の周波数歪の推定とは、別々に実施することが望ましい。 　Frequency distortion is a factor that degrades the demodulation performance of acoustic communication systems, so frequency distortion correction processing is required in acoustic communication systems. It is also possible to estimate and correct the effects of such frequency distortion unique to acoustic equipment through equalization processing in the second communication device 20 . However, when the second communication device 20 estimates and corrects the frequency distortion of the received signal 26 including the influence of the fluctuating delayed wave, the estimation accuracy deteriorates compared to the case of correcting the time-invariant frequency distortion. do. Therefore, it is desirable to separately perform the estimation of the frequency distortion due to the delayed wave, which is a variable value, and the estimation of the frequency distortion, which is a fixed value, unique to the acoustic device.
　音響機器に固有の周波数歪の補正方法として、実施の形態１では、第１の信号処理部１１は、第１の通信機１０の音響信号出力部１２の周波数特性の逆特性と第２の通信機２０の音響信号入力部２３の周波数特性の逆特性とを用いて、プリコーディング処理を行うことで周波数特性が予め補正された送信信号１４を生成し、送信信号１４をアナログ変換した音響送信信号１５を音響信号出力部１２から出力し、第２の通信機２０の音響信号入力部２３から得られた受信信号２６に重畳される周波数歪の影響を低減する例を説明する。 As a method for correcting frequency distortion inherent in acoustic equipment, in Embodiment 1, the first signal processing unit 11 corrects the inverse characteristic of the frequency characteristic of the acoustic signal output unit 12 of the first communication device 10 and the second communication A transmission signal 14 whose frequency characteristics have been corrected in advance is generated by performing precoding processing using the inverse characteristics of the frequency characteristics of the acoustic signal input unit 23 of the equipment 20, and the transmission signal 14 is converted into an analog acoustic transmission signal. 15 is output from the acoustic signal output unit 12 to reduce the effect of frequency distortion superimposed on the received signal 26 obtained from the acoustic signal input unit 23 of the second communication device 20. FIG.
　第１の通信機１０及び第２の通信機２０は、自身の機器の周波数特性を既知であり、メモリ等に格納した音響機器の周波数特性を任意のタイミングで読み出し可能である。これに対して、第１の通信機１０及び第２の通信機２０は、通信相手の音響機器の周波数特性を知らず、第１の通信機１０は、第２の通信機２０から音響信号入力部２３の周波数特性を取得する必要がある。 The first communication device 10 and the second communication device 20 know the frequency characteristics of their own equipment, and can read the frequency characteristics of the acoustic equipment stored in the memory or the like at any timing. On the other hand, the first communication device 10 and the second communication device 20 do not know the frequency characteristics of the acoustic equipment of the communication partner, and the first communication device 10 receives the acoustic signal input from the second communication device 20. 23 frequency characteristics must be obtained.
　このような条件にて音響通信システムを運用するために、実施の形態１では、第１の通信機１０から第２の通信機２０へのデータ通信を実施する前に、第２の通信機２０から第１の通信機１０へ音響信号入力部２３の周波数特性を伝達し、第１の通信機１０にて補正用のプリコーディング係数を算出することを目的としたキャリブレーション設定を事前に実施する。 In order to operate the acoustic communication system under such conditions, in Embodiment 1, before performing data communication from the first communication device 10 to the second communication device 20, the second communication device 20 transmits the frequency characteristics of the acoustic signal input unit 23 to the first communication device 10, and performs calibration settings in advance for the purpose of calculating precoding coefficients for correction in the first communication device 10. .
　実施の形態１に係る音響通信システムの運用モードは、補正用のプリコーディング係数を算出するキャリブレーションモードと、通常のデータ通信を実施するデータ通信モードとから構成される。音響通信システムの運用開始時は、キャリブレーションモードが選択され、第１の通信機１０と第２の通信機２０との間の双方向通信による音響信号のやりとりにより、第１の通信機１０は、第２の通信機２０の音響信号入力部２３の周波数特性を取得し、プリコーディング係数を算出する。音響通信システムは、プリコーディング係数の算出後に、運用モードをキャリブレーションモードからデータ通信モードに切り替え、第１の通信機１０から第２の通信機２０への音響信号による片方向通信を実施する。データ通信モードでは、第１の通信機１０は、キャリブレーションモードにて算出したプリコーディング係数を用いた補正処理によって送信信号１４を生成し、第２の通信機２０への音響送信信号１５の伝送を行う。ここで、音響機器の周波数特性は、時不変の値であるため、第１の通信機１０は、運用モードがデータ通信モードに切り替えられた後は、基本的に同じプリコーディング係数に基づく補正を実施した上でデータ通信を実施すればよい。しかし、例えば、受信端末である第２の通信機２０が、他の第２の通信機に置き換わった場合などのように、再度キャリブレーションが必要になった場合には、第１の通信機１０は、運用モードをキャリブレーションモードへと切り替える。 The operation mode of the acoustic communication system according to Embodiment 1 consists of a calibration mode in which precoding coefficients for correction are calculated and a data communication mode in which normal data communication is performed. At the start of the operation of the acoustic communication system, the calibration mode is selected, and the exchange of acoustic signals by two-way communication between the first communication device 10 and the second communication device 20 causes the first communication device 10 to , the frequency characteristics of the acoustic signal input unit 23 of the second communication device 20 are obtained, and the precoding coefficients are calculated. After calculating the precoding coefficients, the acoustic communication system switches the operation mode from the calibration mode to the data communication mode, and performs one-way communication using acoustic signals from the first communication device 10 to the second communication device 20 . In the data communication mode, the first communication device 10 generates the transmission signal 14 by correction processing using the precoding coefficients calculated in the calibration mode, and transmits the acoustic transmission signal 15 to the second communication device 20. I do. Here, since the frequency characteristic of the audio equipment is a time-invariant value, the first communication device 10 performs correction based on basically the same precoding coefficients after the operation mode is switched to the data communication mode. Data communication may be performed after the implementation. However, when recalibration becomes necessary, for example, when the second communication device 20, which is the receiving terminal, is replaced with another second communication device, the first communication device 10 switches the operational mode to calibration mode.
　図２は、第１の通信機１０の第１の信号処理部１１の構成を示すブロック図である。第１の通信機１０の第１の信号処理部１１は、予め決められたキャリブレーションデータ（一般には、周波数帯域の特性が均一なキャリブレーションデータ）を生成するキャリブレーションデータ生成部１０１と、データ通信モードにて伝送する送信情報を生成する送信情報生成部１０２と、キャリブレーションデータ、又は送信情報のどちらかをプリコーディング処理部へ出力する切替部１０３と、切替部１０３の出力に対してプリコーディング処理を実施するプリコーディング処理部１０４と、プリコーディング処理における係数を算出するプリコーディング係数算出部１０５とを有している。また、第１の信号処理部１１は、音響信号入力部１３から得られた受信信号１６に対してポストコーディング処理を実施するポストコーディング処理部１０６と、ポストコーディング処理における係数を算出するポストコーディング係数算出部１０７と、ポストコーディング処理部１０６からの出力信号について周波数特性を推定する周波数特性推定部１０８とを有している。加えて、第１の信号処理部１１は、周波数特性推定部１０８からの書き込みとプリコーディング係数算出部１０５及びポストコーディング係数算出部１０７への読み出しとが可能な周波数特性メモリ１０９を有している。周波数特性メモリ１０９には、予め音響信号出力部１２の周波数特性、音響信号入力部１３の周波数特性が格納されている。第１の通信機１０の第１の信号処理部１１は、動作制御信号にしたがって各モードにおける信号処理動作を制御する。 FIG. 2 is a block diagram showing the configuration of the first signal processing section 11 of the first communication device 10. As shown in FIG. The first signal processing unit 11 of the first communication device 10 includes a calibration data generation unit 101 that generates predetermined calibration data (generally, calibration data with uniform frequency band characteristics), and a data A transmission information generation unit 102 that generates transmission information to be transmitted in the communication mode, a switching unit 103 that outputs either calibration data or transmission information to a precoding processing unit, and a precoding unit for the output of the switching unit 103. It has a precoding processing unit 104 that performs coding processing and a precoding coefficient calculation unit 105 that calculates coefficients in the precoding processing. The first signal processing unit 11 also includes a post-coding processing unit 106 that performs post-coding processing on the received signal 16 obtained from the acoustic signal input unit 13, and a post-coding coefficient that calculates coefficients in the post-coding processing. It has a calculating section 107 and a frequency characteristic estimating section 108 for estimating the frequency characteristic of the output signal from the postcoding processing section 106 . In addition, the first signal processing unit 11 has a frequency characteristic memory 109 in which writing from the frequency characteristic estimating unit 108 and reading to the precoding coefficient calculating unit 105 and the postcoding coefficient calculating unit 107 are possible. . The frequency characteristic memory 109 stores the frequency characteristic of the acoustic signal output section 12 and the frequency characteristic of the acoustic signal input section 13 in advance. The first signal processing section 11 of the first communication device 10 controls the signal processing operation in each mode according to the operation control signal.
　図３は、第２の信号処理部２１の構成を示すブロック図である。第２の信号処理部２１は、周波数帯域の特性が均一なキャリブレーションデータを生成するキャリブレーションデータ生成部２０１と、キャリブレーションデータに対してプリコーディング処理を実施するプリコーディング処理部２０２と、プリコーディング処理における係数を算出するプリコーディング係数算出部２０３とを有している。また、第２の信号処理部２１は、音響信号入力部２３から得られた受信信号２６の接続先を決定する接続先選択部２０４と、接続先選択部２０４に接続先として選択された場合に送信信号に対してポストコーディング処理を実施するポストコーディング処理部２０５と、ポストコーディング処理における係数を算出するポストコーディング係数算出部２０６と、ポストコーディング処理部２０５の出力信号について周波数特性を推定する周波数特性推定部２０７と、接続先選択部２０４に接続先として選択された場合に送信信号１４の伝搬路特性を算出する伝搬路特性推定部２０８と、推定した伝搬路特性を用いて等化処理を実施する等化処理部２０９と、等化処理後の信号を復調する復調部２１０とを有している。加えて、第２の信号処理部２１は、周波数特性推定部２０７からの書き込みとプリコーディング係数算出部２０３、ポストコーディング係数算出部２０６とへの読み出しが可能な周波数特性メモリ２１１を有している。周波数特性メモリ２１１には、予め音響信号出力部２２の周波数特性、音響信号入力部２３の周波数特性が格納されている。第２の信号処理部２１は、動作制御信号にしたがって各モードにおける信号処理動作を制御する。 FIG. 3 is a block diagram showing the configuration of the second signal processing section 21. As shown in FIG. The second signal processing unit 21 includes a calibration data generation unit 201 that generates calibration data with uniform frequency band characteristics, a precoding processing unit 202 that performs precoding processing on the calibration data, and a precoding processing unit 202 that performs precoding processing on the calibration data. and a precoding coefficient calculation unit 203 for calculating coefficients in the coding process. In addition, the second signal processing unit 21 includes a connection destination selection unit 204 that determines the connection destination of the received signal 26 obtained from the acoustic signal input unit 23, and when the connection destination selection unit 204 selects the connection destination, A postcoding processing unit 205 that performs postcoding processing on a transmission signal, a postcoding coefficient calculation unit 206 that calculates coefficients in the postcoding processing, and a frequency characteristic that estimates the frequency characteristics of the output signal of the postcoding processing unit 205. An estimating unit 207, a channel characteristics estimating unit 208 that calculates the channel characteristics of the transmission signal 14 when selected as a connection destination by the connection destination selecting unit 204, and performs equalization processing using the estimated channel characteristics. and a demodulator 210 for demodulating the equalized signal. In addition, the second signal processing unit 21 has a frequency characteristic memory 211 in which data can be written from the frequency characteristic estimation unit 207 and read out to the precoding coefficient calculation unit 203 and the postcoding coefficient calculation unit 206. . The frequency characteristic memory 211 stores the frequency characteristic of the acoustic signal output section 22 and the frequency characteristic of the acoustic signal input section 23 in advance. The second signal processing section 21 controls the signal processing operation in each mode according to the operation control signal.
　図４は、図２に示される第１の通信機１０のハードウェア構成の例を示す図である。図４に示されるように、第１の通信機１０は、ＣＰＵ（Ｃｅｎｔｒａｌ　Ｐｒｏｃｅｓｓｉｎｇ　Ｕｎｉｔ）などのプロセッサ１５１と、揮発性の記憶装置であるメモリ１５２と、ハードディスクドライブ（ＨＤＤ）又はソリッドステートドライブ（ＳＳＤ）などの不揮発性の記憶装置１５３と、デジタルアナログ変換器１５４およびスピーカ１５５から成る音響信号出力部１２と、アナログデジタル変換器１５６およびマイク１５７から成る音響信号入力部１３とを有している。メモリ１５２は、例えば、ＲＡＭ（Ｒａｎｄｏｍ　Ａｃｃｅｓｓ　Ｍｅｍｏｒｙ）などの、揮発性の半導体メモリである。 FIG. 4 is a diagram showing an example of the hardware configuration of the first communication device 10 shown in FIG. As shown in FIG. 4, the first communication device 10 includes a processor 151 such as a CPU (Central Processing Unit), a memory 152 that is a volatile storage device, a hard disk drive (HDD) or solid state drive (SSD). ), an acoustic signal output section 12 comprising a digital-to-analog converter 154 and a speaker 155, and an acoustic signal input section 13 comprising an analog-to-digital converter 156 and a microphone 157. The memory 152 is, for example, a volatile semiconductor memory such as RAM (Random Access Memory).
　第１の通信機１０の第１の信号処理部１１の各機能は、処理回路により実現される。処理回路は、専用のハードウェアであっても、メモリ１５２に格納されるプログラムを実行するプロセッサ１５１であってもよい。プロセッサ１５１は、処理装置、演算装置、マイクロプロセッサ、マイクロコンピュータ、及びＤＳＰ（Ｄｉｇｉｔａｌ　Ｓｉｇｎａｌ　Ｐｒｏｃｅｓｓｏｒ）のいずれであってもよい。図２に示される動作制御信号は、例えば、プロセッサ１５１によって生成される。 Each function of the first signal processing unit 11 of the first communication device 10 is realized by a processing circuit. The processing circuitry may be dedicated hardware or processor 151 executing programs stored in memory 152 . The processor 151 may be any of a processing device, an arithmetic device, a microprocessor, a microcomputer, and a DSP (Digital Signal Processor). The motion control signals shown in FIG. 2 are generated by processor 151, for example.
　処理回路が専用のハードウェアである場合、処理回路は、例えば、単一回路、複合回路、プログラム化したプロセッサ、並列プログラム化したプロセッサ、ＡＳＩＣ（Ａｐｐｌｉｃａｔｉｏｎ　Ｓｐｅｃｉｆｉｃ　Ｉｎｔｅｇｒａｔｅｄ　Ｃｉｒｃｕｉｔ）、ＦＰＧＡ（Ｆｉｅｌｄ－Ｐｒｏｇｒａｍｍａｂｌｅ　Ｇａｔｅ　Ａｒｒａｙ）、又はこれらのうちのいずれかを組み合わせたものである。処理回路がプロセッサ１５１である場合、音響通信を行うための音響通信プログラムは、ソフトウェア、ファームウェア、又はソフトウェアとファームウェアとの組み合わせにより実現される。ソフトウェア及びファームウェアは、プログラムとして記述され、メモリ１５２に格納される。プロセッサ１５１は、メモリ１５２に記憶されたプログラムを読み出して実行することにより、図２に示される各部の機能を実現する。 If the processing circuit is dedicated hardware, the processing circuit may be, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array) ), or a combination of any of these. When the processing circuit is the processor 151, an acoustic communication program for performing acoustic communication is implemented by software, firmware, or a combination of software and firmware. Software and firmware are written as programs and stored in memory 152 . The processor 151 implements the functions of the units shown in FIG. 2 by reading and executing programs stored in the memory 152 .
　なお、第１の通信機１０の第１の信号処理部１１は、一部を専用のハードウェアで実現し、一部をソフトウェア又はファームウェアで実現するようにしてもよい。このように、処理回路は、ハードウェア、ソフトウェア、ファームウェア、又はこれらのうちのいずれかの組み合わせによって、上述の各機能を実現することができる。 It should be noted that the first signal processing unit 11 of the first communication device 10 may be partially realized by dedicated hardware and partially realized by software or firmware. As such, the processing circuitry may implement each of the functions described above in hardware, software, firmware, or any combination thereof.
　図５は、図３に示される第２の通信機２０のハードウェア構成の例を示す図である。図５に示されるように、第２の通信機２０は、ＣＰＵなどのプロセッサ２５１と、揮発性の記憶装置であるメモリ２５２と、ＨＤＤ又はＳＳＤなどの不揮発性の記憶装置２５３と、デジタルアナログ変換器２５４およびスピーカ２５５から成る音響信号出力部２２と、アナログデジタル変換器２５６およびマイク２５７から成る音響信号入力部２３とを有している。メモリ２５２は、例えば、ＲＡＭなどの、揮発性の半導体メモリである。 FIG. 5 is a diagram showing an example of the hardware configuration of the second communication device 20 shown in FIG. As shown in FIG. 5, the second communication device 20 includes a processor 251 such as a CPU, a memory 252 which is a volatile storage device, a nonvolatile storage device 253 such as an HDD or SSD, and a digital-to-analog converter. It has an acoustic signal output section 22 consisting of a device 254 and a speaker 255 and an acoustic signal input section 23 consisting of an analog-to-digital converter 256 and a microphone 257 . Memory 252 is, for example, a volatile semiconductor memory such as RAM.
　第２の通信機２０の第２の信号処理部２１の各機能は、処理回路により実現される。処理回路は、専用のハードウェアであっても、メモリ２５２に格納されるプログラムを実行するプロセッサ２５１であってもよい。プロセッサ２５１は、処理装置、演算装置、マイクロプロセッサ、マイクロコンピュータ、及びＤＳＰのいずれであってもよい。図３に示される動作制御信号は、例えば、プロセッサ２５１によって生成される。 Each function of the second signal processing section 21 of the second communication device 20 is realized by a processing circuit. The processing circuitry may be dedicated hardware or processor 251 executing programs stored in memory 252 . Processor 251 may be any of a processing unit, an arithmetic unit, a microprocessor, a microcomputer, and a DSP. The motion control signals shown in FIG. 3 are generated by processor 251, for example.
　処理回路が専用のハードウェアである場合、処理回路は、例えば、単一回路、複合回路、プログラム化したプロセッサ、並列プログラム化したプロセッサ、ＡＳＩＣ、ＦＰＧＡ、又はこれらのうちのいずれかを組み合わせたものである。処理回路がプロセッサ１５１である場合、音響通信を行うための音響通信プログラムは、ソフトウェア、ファームウェア、又はソフトウェアとファームウェアとの組み合わせにより実現される。ソフトウェア及びファームウェアは、プログラムとして記述され、メモリ２５２に格納される。プロセッサ２５１は、メモリ２５２に記憶されたプログラムを読み出して実行することにより、図２に示される各部の機能を実現する。 Where the processing circuitry is dedicated hardware, the processing circuitry may be, for example, a single circuit, multiple circuits, programmed processors, parallel programmed processors, ASICs, FPGAs, or any combination thereof. is. When the processing circuit is the processor 151, an acoustic communication program for performing acoustic communication is implemented by software, firmware, or a combination of software and firmware. Software and firmware are written as programs and stored in memory 252 . The processor 251 implements the functions of the units shown in FIG. 2 by reading and executing programs stored in the memory 252 .
　なお、第２の通信機２０の第２の信号処理部２１は、一部を専用のハードウェアで実現し、一部をソフトウェア又はファームウェアで実現するようにしてもよい。このように、処理回路は、ハードウェア、ソフトウェア、ファームウェア、又はこれらのうちのいずれかの組み合わせによって、上述の各機能を実現することができる。 It should be noted that the second signal processing unit 21 of the second communication device 20 may be partially realized by dedicated hardware and partially realized by software or firmware. As such, the processing circuitry may implement each of the functions described above in hardware, software, firmware, or any combination thereof.
《１－２》動作
　図６は、実施の形態１に係る音響通信システムのキャリブレーションモードの動作を示すフローチャートである。なお、本音響通信システムは、データ通信モードにおいて、第２の通信機２０の移動を許容しているが、キャリブレーションモード中は、伝搬路特性が時不変となるようにするため、第１の通信機１０及び第２の通信機２０は移動しないことが望ましい。 <<1-2>> Operation FIG. 6 is a flow chart showing the operation in the calibration mode of the acoustic communication system according to the first embodiment. In the data communication mode, this acoustic communication system allows the second communication device 20 to move. It is desirable that the communicator 10 and the second communicator 20 not move.
　第１の通信機１０は、キャリブレーションモードが開始された後、切替部１０３の出力をキャリブレーションデータ生成部１０１からの出力信号とした上で、キャリブレーションデータ生成ステップＳ１０１にてキャリブレーションデータを生成する。 After the calibration mode is started, the first communication device 10 uses the output of the switching unit 103 as the output signal from the calibration data generation unit 101, and then generates the calibration data in the calibration data generation step S101. Generate.
　次に、プリコーディング係数算出ステップＳ１０２では、第１の通信機１０は、周波数特性メモリ１０９より音響信号出力部１２の周波数特性（ＴＳ）を読み出し、音響信号出力部１２の周波数特性（ＴＳ）の逆特性（１／ＴＳ）をプリコーディング係数とする。 Next, in precoding coefficient calculation step S102, the first communication device 10 reads out the frequency characteristic (TS) of the acoustic signal output unit 12 from the frequency characteristic memory 109, and reads the frequency characteristic (TS) of the acoustic signal output unit 12. Let the inverse characteristic (1/TS) be the precoding coefficient.
　さらに、プリコーディング処理ステップＳ１０３では、第１の通信機１０は、キャリブレーションデータに対して、プリコーディング係数算出ステップＳ１０２にて算出した逆特性（１／ＴＳ）をプリコーディング係数として用いたプリコーディング処理を実施する。 Further, in precoding processing step S103, the first communication device 10 precodes the calibration data using the inverse characteristic (1/TS) calculated in precoding coefficient calculation step S102 as a precoding coefficient. Take action.
　第１の通信機１０は、これらの処理を実施することで得られた送信信号１４を、音響信号出力部１２から音響送信信号１５として出力する。ここで、送信信号１４は、音響信号出力部１２を通る際に音響信号出力部１２が有する周波数歪の影響を受けるが、送信信号１４は、予め音響信号出力部１２の周波数特性（ＴＳ）の逆特性（１／ＴＳ）により補正されているため、音響送信信号１５の周波数特性は、フラットである。 The first communication device 10 outputs the transmission signal 14 obtained by performing these processes as the acoustic transmission signal 15 from the acoustic signal output unit 12 . Here, the transmission signal 14 is affected by the frequency distortion of the acoustic signal output section 12 when passing through the acoustic signal output section 12. Since it is corrected by the inverse characteristic (1/TS), the frequency characteristic of the acoustic transmission signal 15 is flat.
　次に、第２の通信機２０は、ポストコーディング係数算出ステップＳ１０４にて周波数特性メモリ２１１より音響信号入力部２３の周波数特性（ＲＭ）を読み出し、音響信号入力部２３の周波数特性（ＲＭ）の逆特性（１／ＲＭ）をポストコーディング係数に設定する。 Next, the second communication device 20 reads out the frequency characteristic (RM) of the acoustic signal input unit 23 from the frequency characteristic memory 211 in postcoding coefficient calculation step S104, and reads the frequency characteristic (RM) of the acoustic signal input unit 23. Set the inverse characteristic (1/RM) to the postcoding coefficients.
　ポストコーディング処理ステップＳ１０５では、第２の通信機２０は、音響信号入力部２３より得られた受信信号２６に対して、ポストコーディング係数算出ステップＳ１０４にて算出したポストコーディング係数を用いたポストコーディング処理を実施する。 In postcoding processing step S105, the second communication device 20 performs postcoding processing on the received signal 26 obtained from the acoustic signal input unit 23 using the postcoding coefficients calculated in the postcoding coefficient calculation step S104. to implement.
　その後、周波数特性推定ステップＳ１０６では、第２の通信機２０は、ポストコーディング処理部２０５からの出力について周波数特性の推定を実施し、推定した周波数特性を周波数特性メモリ２１１内の一時メモリに格納する。ここで、ポストコーディング処理部２０５からの出力信号は、音響信号入力部２３を通る際に受けた周波数歪の影響をポストコーディング処理にて補正されているため、一時メモリに格納する周波数特性は、第１の通信機１０の音響信号出力部１２と第２の通信機２０の音響信号入力部２３の周波数歪の影響を受けていない伝搬路特性（Ｈ）とみなすことができる。 After that, in the frequency characteristic estimation step S106, the second communication device 20 estimates the frequency characteristic of the output from the postcoding processing unit 205, and stores the estimated frequency characteristic in the temporary memory in the frequency characteristic memory 211. . Here, since the output signal from the post-coding processing unit 205 has undergone post-coding processing to correct the influence of frequency distortion received when passing through the acoustic signal input unit 23, the frequency characteristic stored in the temporary memory is It can be regarded as a propagation path characteristic (H) that is not affected by frequency distortion of the acoustic signal output section 12 of the first communication device 10 and the acoustic signal input section 23 of the second communication device 20 .
　次に、第２の通信機２０は、プリコーディング係数算出ステップＳ１０７にて、周波数特性メモリ２１１の一時メモリに格納した周波数特性（Ｈ）と音響信号出力部２２の周波数特性（ＲＳ）を読み出し、これらの周波数特性を乗算した値（Ｈ×ＲＳ）の逆特性（１／（Ｈ×ＲＳ））をプリコーディング係数として設定する。そして、第２の通信機２０は、周波数特性メモリ２１１より音響信号入力部２３の周波数特性（ＲＭ）をさらに読み出し、（１／（Ｈ×ＲＳ））に乗算する。 Next, in the precoding coefficient calculation step S107, the second communication device 20 reads the frequency characteristic (H) stored in the temporary memory of the frequency characteristic memory 211 and the frequency characteristic (RS) of the acoustic signal output unit 22, An inverse characteristic (1/(H×RS)) of a value (H×RS) obtained by multiplying these frequency characteristics is set as a precoding coefficient. Then, the second communication device 20 further reads the frequency characteristic (RM) of the acoustic signal input section 23 from the frequency characteristic memory 211 and multiplies it by (1/(H×RS)).
　また、第２の通信機２０は、キャリブレーションデータ生成ステップＳ１０８にて、新たにキャリブレーションデータを生成する。ここで、生成するキャリブレーションデータの系列は、キャリブレーションデータ生成ステップＳ１０１にて生成したキャリブレーション信号と同じ系列である。プリコーディング処理ステップＳ１０９では、第２の通信機２０は、生成したキャリブレーションデータに対してプリコーディング係数算出ステップＳ１０７にて算出したプリコーディング係数（ＲＭ／（Ｈ×ＲＳ））を用いたプリコーディング処理を実施する。 Also, the second communication device 20 newly generates calibration data in the calibration data generation step S108. Here, the generated calibration data series is the same series as the calibration signal generated in the calibration data generation step S101. In precoding processing step S109, the second communication device 20 precodes the generated calibration data using the precoding coefficients (RM/(H×RS)) calculated in precoding coefficient calculation step S107. Take action.
　第２の通信機２０は、プリコーディング処理されたキャリブレーションデータを音響信号出力部２２から音響送信信号２５として出力し、第１の通信機１０は、音響信号入力部１３により音響送信信号２５を受信信号１６として受け取る。ここで、受け取った受信信号１６の周波数特性には、第２の通信機２０で実施したプリコーディング処理によって、第２の通信機２０の音響信号入力部２３の周波数特性（ＲＭ）と第１の通信機１０の音響信号入力部１３の周波数特性（ＴＭ）の影響が残留している。 The second communication device 20 outputs the precoded calibration data as an acoustic transmission signal 25 from the acoustic signal output unit 22, and the first communication device 10 outputs the acoustic transmission signal 25 from the acoustic signal input unit 13. Received as received signal 16 . Here, the frequency characteristic (RM) of the acoustic signal input section 23 of the second communication device 20 and the first The influence of the frequency characteristic (TM) of the acoustic signal input section 13 of the communication device 10 remains.
　第１の通信機１０は、ポストコーディング係数算出ステップＳ１１０にて、周波数特性メモリ１０９より音響信号入力部１３の周波数特性（ＴＭ）を読み出し、その逆特性（１／ＴＭ）をポストコーディング係数として設定する。ポストコーディング処理ステップＳ１１１では、第１の通信機１０は、音響信号入力部１３から得た受信信号１６に対してポストコーディング係数を用いてポストコーディング処理を実施する。このポストコーディング処理後の信号には、第２の通信機２０の音響信号入力部２３の周波数特性（ＲＭ）の影響が残留している。 In the postcoding coefficient calculation step S110, the first communication device 10 reads the frequency characteristic (TM) of the acoustic signal input unit 13 from the frequency characteristic memory 109, and sets the inverse characteristic (1/TM) as the postcoding coefficient. do. In postcoding processing step S111, the first communication device 10 performs postcoding processing on the received signal 16 obtained from the acoustic signal input unit 13 using the postcoding coefficients. The influence of the frequency characteristic (RM) of the acoustic signal input section 23 of the second communication device 20 remains in the signal after this postcoding process.
　第１の通信機１０は、周波数特性推定ステップＳ１１２にて、ポストコーディング処理後の信号の周波数特性を推定し、推定結果を音響信号入力部２３の周波数特性とみなして周波数特性メモリ１０９に格納する。最後に、第１の通信機１０は、プリコーディング係数算出ステップＳ１１３にて、周波数特性メモリ１０９より音響信号入力部２３の周波数特性（ＲＭ）と音響信号出力部１２の周波数特性（ＴＳ）を読み出し、その逆特性を乗算した値（１／（ＲＭ×ＴＳ））をプリコーディング係数として設定する。 In the frequency characteristic estimation step S112, the first communication device 10 estimates the frequency characteristic of the post-coding signal, regards the estimation result as the frequency characteristic of the acoustic signal input unit 23, and stores it in the frequency characteristic memory 109. . Finally, in the precoding coefficient calculation step S113, the first communication device 10 reads the frequency characteristics (RM) of the acoustic signal input section 23 and the frequency characteristics (TS) of the acoustic signal output section 12 from the frequency characteristic memory 109. , and a value (1/(RM×TS)) multiplied by its inverse characteristic is set as a precoding coefficient.
　プリコーディング係数算出ステップＳ１１３が終了した後、音響通信システムは、キャリブレーションモードが完了したとし、データ通信モードへと移行する。データ通信モードでは、第１の通信機１０は、切替部１０３の出力を送信情報生成部１０２の出力に切り替えた上で、プリコーディング係数算出ステップＳ１１３にて設定したプリコーディング係数を用いて送信情報に対するプリコーディング処理を実施し音響信号出力部１２より音響送信信号１５として出力する。一方、第２の通信機２０は、接続先選択部２０４の接続先を伝搬路特性推定部２０８とした上で、音響信号入力部２３から得られた受信信号２６の伝搬路特性を算出し、等化処理部２０９にて伝搬路特性推定値を用いて等化処理したのちに復調部２１０にて復調処理を施して元の送信情報を生成する。 After the precoding coefficient calculation step S113 ends, the acoustic communication system assumes that the calibration mode is completed, and shifts to the data communication mode. In the data communication mode, the first communication device 10 switches the output of the switching unit 103 to the output of the transmission information generation unit 102, and then uses the precoding coefficients set in the precoding coefficient calculation step S113 to generate transmission information. , and is output as an acoustic transmission signal 15 from the acoustic signal output unit 12 . On the other hand, the second communication device 20 sets the connection destination of the connection destination selection unit 204 to the propagation path characteristic estimation unit 208, calculates the propagation path characteristics of the received signal 26 obtained from the acoustic signal input unit 23, After the equalization processing section 209 performs equalization processing using the propagation path characteristics estimation value, the demodulation section 210 performs demodulation processing to generate the original transmission information.
《１－３》効果
　実施の形態１によるキャリブレーションモードでは、第２の通信機２０が、伝搬路特性（Ｈ）を推定し、キャリブレーションデータに対して推定した伝搬路特性と音響信号出力部２２からの周波数歪とを補正するプリコーディング係数を算出した上で、音響信号入力部２３の周波数特性をプリコーディング係数に更に重畳させることによって、第１の通信機１０に音響信号入力部２３の周波数特性（ＲＭ）のみを伝えることが可能である。そのため、実施の形態１は、キャリブレーション時に第１の通信機１０と第２の通信機２０との間に空間的に長い距離があるような環境下でも、第１の通信機１０が音響信号入力部２３の周波数歪を正しく推定してプリコーディング係数（１／（ＲＭ×ＴＳ））に反映できる。よって、データ通信時における音響通信システムにおける復調性能を向上させることができる。 <<1-3>> Effect In the calibration mode according to the first embodiment, the second communication device 20 estimates the channel characteristics (H), and the estimated channel characteristics and the acoustic signal output unit for the calibration data. After calculating the precoding coefficients for correcting the frequency distortion from 22, the frequency characteristic of the acoustic signal input unit 23 is further superimposed on the precoding coefficients, thereby providing the first communication device 10 with the sound signal input unit 23. It is possible to convey only the frequency response (RM). Therefore, in the first embodiment, even in an environment where there is a long spatial distance between the first communication device 10 and the second communication device 20 during calibration, the first communication device 10 can generate an acoustic signal. The frequency distortion of the input unit 23 can be correctly estimated and reflected in the precoding coefficient (1/(RM×TS)). Therefore, it is possible to improve the demodulation performance in the acoustic communication system during data communication.
《１－４》変形例１
　図７は、実施の形態１の変形例１に係る音響通信システムの第１の通信機の第１の信号処理部１１ａの構成を示すブロック図である。図７の音響通信システムは、第１の信号処理部１１ａが、時間ダイバ―シチ用データメモリ１２２と時間ダイバ―シチ処理部１２１とを有する点において、図１から図６に示される音響通信システムと相違する。 <<1-4>> Modification 1
FIG. 7 is a block diagram showing the configuration of the first signal processing unit 11a of the first communication device of the acoustic communication system according to Modification 1 of Embodiment 1. As shown in FIG. The acoustic communication system shown in FIG. 7 is similar to the acoustic communication system shown in FIGS. differ from
　ポストコーディング処理の際には、雑音強調の影響を低減する必要がある。実施の形態１のキャリブレーションモードにおけるポストコーディング処理についても雑音強調の影響を低減することが望ましい。そこで、変形例１の第１の通信機の第１の信号処理部１１ａは、複数の音響送信信号２５を保管する時間ダイバ―シチ用データメモリ１２２と、時間ダイバ―シチ用データメモリから読み出した複数の音響送信信号２５を時間同期させた上で平均化処理する時間ダイバ―シチ処理部１２１をさらに有している。この点以外に関し、変形例１に係る音響通信システムは、図１から図６に示されるものと同じである。 　In the postcoding process, it is necessary to reduce the effects of noise enhancement. It is also desirable to reduce the effects of noise enhancement in postcoding processing in the calibration mode of the first embodiment. Therefore, the first signal processing unit 11a of the first communication device of Modification 1 reads out from the time-diversity data memory 122 storing a plurality of acoustic transmission signals 25 and the time-diversity data memory. It further has a time diversity processing unit 121 for averaging the plurality of acoustic transmission signals 25 after synchronizing them in time. Other than this point, the acoustic communication system according to Modification 1 is the same as that shown in FIGS.
　第１の通信機にて雑音強調が発生しうるのは、図６におけるポストコーディング処理ステップＳ１１１であり、プリコーディング処理ステップＳ１０９、ポストコーディング係数算出ステップＳ１１０の間の音響送信信号２５の伝送にて音響送信信号２５に重畳する白色雑音が雑音強調の原因となる。そこで、ポストコーディング処理ステップＳ１１１を実施する前に、第２の通信機２０は、音響送信信号２５の伝送を複数回実施し、第１の通信機は、音響信号入力部１３から得た複数の受信信号１６を時間ダイバ―シチ用データメモリに格納し、その後時間ダイバ―シチ用データメモリ１２２から読み出した信号をダイバ―シチ処理部１２１にて平均化した上でポストコーディング処理部１０６に引き渡す。 Noise enhancement can occur in the first communication device in the postcoding processing step S111 in FIG. White noise superimposed on the acoustic transmission signal 25 causes noise enhancement. Therefore, before performing the postcoding processing step S111, the second communication device 20 transmits the acoustic transmission signal 25 a plurality of times, and the first communication device receives a plurality of The received signal 16 is stored in the time diversity data memory, and then the signal read out from the time diversity data memory 122 is averaged by the diversity processing unit 121 and transferred to the postcoding processing unit 106 .
　本処理によって受信信号を平均化することで、ポストコーディング処理ステップＳ１１１における雑音強調の影響を低減させることができる。 By averaging the received signal by this process, the influence of noise enhancement in the postcoding process step S111 can be reduced.
　また、第２の通信機２０に、同様の時間ダイバ―シチ用データメモリと時間ダイバ―シチ処理部とを備え、ポストコーディング処理ステップＳ１０５において、同様の処理を実施することも可能である。 It is also possible to equip the second communication device 20 with a similar data memory for time diversity and a time diversity processing unit, and perform similar processing in the postcoding processing step S105.
《１－５》変形例２
　図８は、実施の形態１の変形例２に係る音響通信システムの第１の通信機の第１の信号処理部１１ｂの構成を示すブロック図である。図８の音響通信システムは、第１の信号処理部１１ｂが、干渉波電力計測部１３１と干渉波電力メモリ１３２とを有する点、及び周波数特性推定部１０８ａによって行われる処理の内容の点において、図１から図６に示される音響通信システムと相違する。 <<1-5>> Modification 2
FIG. 8 is a block diagram showing the configuration of the first signal processing section 11b of the first communication device of the acoustic communication system according to Modification 2 of Embodiment 1. As shown in FIG. In the acoustic communication system of FIG. 8, the first signal processing unit 11b has an interference wave power measurement unit 131 and an interference wave power memory 132, and the details of the processing performed by the frequency characteristic estimation unit 108a are as follows: It differs from the acoustic communication system shown in FIGS.
　上記変形例１では、伝搬路にて発生する雑音が白色雑音である場合を説明した。しかし、例えば、様々な周波数帯の機器音が発生する工場内等で本音響通信システムを実現する場合、白色雑音に加えて特定の周波数帯に干渉波が発生した際にも第１の通信機１０が第２の通信機２０の音響信号入力部２３の周波数歪を正しく推定できることが望ましい。ここで、白色雑音は、平均化により電力を低減できるが、このような干渉波は、平均化による電力の低減ができないという差異がある。そこで、第１の通信機の第１の信号処理部１１ｂは、周囲の干渉波を計測し電力を算出する干渉波電力計測部１３１と、計測した干渉波の周波数帯と干渉波電力を格納する干渉波電力メモリ１３２とをさらに有している。この点以外に関し、変形例２に係る音響通信システムは、図１から図６に示されるものと同じである。 In the above modified example 1, the case where the noise generated in the propagation path is white noise has been described. However, for example, when realizing this acoustic communication system in a factory where equipment sounds of various frequency bands are generated, even if interference waves occur in a specific frequency band in addition to white noise, the first communication device 10 can correctly estimate the frequency distortion of the acoustic signal input section 23 of the second communication device 20 . Here, the power of white noise can be reduced by averaging, but the power of such an interference wave cannot be reduced by averaging. Therefore, the first signal processing unit 11b of the first communication device includes an interference wave power measurement unit 131 that measures the surrounding interference wave and calculates the power, and stores the measured frequency band of the interference wave and the interference wave power. It further has an interference wave power memory 132 . Other than this point, the acoustic communication system according to Modification 2 is the same as that shown in FIGS.
　第１の通信機は、キャリブレーションモード開始時に干渉波電力計測部１３１にて計測した干渉波の情報を干渉波電力メモリ１３２に格納し、キャリブレーションモードにおける周波数特性推定ステップＳ１１２にて、周波数特性推定部１０８は、干渉波電力メモリ１３２を参照した上で、予め定めた閾値を超える干渉波電力が発生した周波数帯を読み出し、本周波数帯における周波数特性を、本周波数帯域の希望の周波数帯における周波数特性を用いて補間処理することにより推定する。なお、補間処理の方法としては、一次補間又はフィルタリングを用いることができる。 The first communication device stores, in the interference wave power memory 132, the information of the interference wave measured by the interference wave power measuring unit 131 at the start of the calibration mode, and performs frequency characteristic estimation step S112 in the calibration mode. The estimating unit 108 refers to the interference wave power memory 132, reads out the frequency band in which the interference wave power exceeding the predetermined threshold occurs, and calculates the frequency characteristics in this frequency band in the desired frequency band of this frequency band. It is estimated by performing interpolation processing using frequency characteristics. Note that primary interpolation or filtering can be used as a method of interpolation processing.
　本処理によって、干渉波が生じる環境下で伝送された音響送信信号２５について周波数特性の推定精度を向上できる。 This processing can improve the accuracy of estimating the frequency characteristics of the acoustic transmission signal 25 transmitted in an environment where interference waves occur.
　また、第２の通信機２０に、同様の干渉波電力計測部と干渉波電力メモリとを備え、周波数特性推定ステップＳ１０６において、同様の処理を実施することも可能である。 Also, it is possible to equip the second communication device 20 with a similar interference wave power measuring unit and interference wave power memory, and perform similar processing in the frequency characteristic estimation step S106.
《１－５》変形例３
　図９は、実施の形態１の変形例３に係る音響通信システムの第１の通信機の第１の信号処理部１１ｃの構成を示すブロック図である。図９の音響通信システムは、第１の信号処理部１１ｃが、プリコーディング係数メモリ１４２と、機種コード取得部１４１とを有する点において、図１から図６に示される音響通信システムと相違する。 <<1-5>> Variation 3
FIG. 9 is a block diagram showing the configuration of the first signal processing unit 11c of the first communication device of the acoustic communication system according to Modification 3 of Embodiment 1. As shown in FIG. The acoustic communication system in FIG. 9 differs from the acoustic communication systems shown in FIGS. 1 to 6 in that the first signal processing section 11c has a precoding coefficient memory 142 and a model code obtaining section 141. FIG.
　上記例では、受信機である第２の通信機２０がスマート端末である例を説明しているが、このスマート端末は、常に同じ機種である必要はなく、音響通信システムの運用中に別のスマート端末に置換することも可能である。つまり、第２の通信機２０となり得る複数の候補通信機が存在し、複数の候補通信機が異なる機種コードを有している場合がある。このよう場合、スマート端末は、機種及び個体ごとに音響機器の周波数特性が異なる可能性があるため、再度、音響通信システムの運用モードをキャリブレーションモードに切り替える必要がある。そこで、第２の通信機の候補として複数の機種が存在する場合に、図２において、機種コードとプリコーディング係数とを紐づけて保管するプリコーディング係数メモリ１４２と、機種コードを取得する機種コード取得部１４１とを有する構成とし、機種コードとプリコーディング係数を紐づけて保管する例を説明する。 In the above example, the second communication device 20, which is the receiver, is a smart terminal. It is also possible to replace it with a smart terminal. In other words, there are multiple candidate communication devices that can be the second communication device 20, and the multiple candidate communication devices may have different model codes. In such a case, smart terminals may have different frequency characteristics of acoustic equipment for each model and individual, so it is necessary to switch the operation mode of the acoustic communication system to the calibration mode again. Therefore, when there are a plurality of models as candidates for the second communication device, in FIG. An example will be described in which the model code and the precoding coefficient are stored in association with each other.
　第１の通信機は、キャリブレーションモード開始前に機種コード取得部より得た第２の通信機２０の機種コードを読み出す。ここで、第２の通信機２０の機種コードを知る方法は、例えば、第２の通信機２０からの無線伝送（すなわち、電波又は音波による通信）及び、第１の通信機１０への手打ち入力（すなわち、ユーザ操作による入力）がある。第２の通信機２０の機種コードに紐づくプリコーディング係数がプリコーディング係数メモリ１４２に存在しない場合は、そのままキャリブレーションモードに移行し、キャリブレーションモード終了時に第２の通信機２０の機種コードと算出したプリコーディング係数をプリコーディング係数メモリに格納する。また、第２の通信機２０の機種コードに紐づくプリコーディング係数がプリコーディング係数メモリ１４２に存在する場合には、キャリブレーションモードの動作をスキップして、読み出したプリコーディング係数をデータ通信モードにおけるプリコーディング係数として設定すればよい。 The first communication device reads the model code of the second communication device 20 obtained from the model code acquisition unit before starting the calibration mode. Here, the method of knowing the model code of the second communication device 20 is, for example, wireless transmission from the second communication device 20 (that is, communication by radio waves or sound waves) and manual input to the first communication device 10. (that is, input by user operation). If the precoding coefficient associated with the model code of the second communication device 20 does not exist in the precoding coefficient memory 142, the calibration mode is entered as it is, and when the calibration mode ends, the model code of the second communication device 20 is The calculated precoding coefficients are stored in a precoding coefficient memory. Further, when the precoding coefficients associated with the model code of the second communication device 20 exist in the precoding coefficient memory 142, the operation in the calibration mode is skipped, and the read precoding coefficients are stored in the data communication mode. It may be set as a precoding coefficient.
　このような動作とすることで、第２の通信機２０の候補が複数存在する場合にキャリブレーション設定の回数を削減することができる。 With such an operation, it is possible to reduce the number of calibration settings when there are multiple candidates for the second communication device 20 .
《２》実施の形態２
《２－１》構成
　実施の形態１では、送受信機である第１及び第２の通信機１０、２０は、自身が有する音響機器の周波数特性を既知であることを前提とした。しかし、第２の通信機２０がスマート端末である場合、スマート端末自身が有する音響信号出力部及び音響信号入力部の周波数特性は、開示されているとは限らないため、前述の前提が成り立たないケースもありうる。そこで、実施の形態２に係る音響通信システムでは、受信機として使用される第２の通信機３０が自身の音響機器の周波数特性を取得不可の場合に、第２の通信機３０から第１の通信機１０へ、第２の通信機３０の音響信号入力部２３の周波数特性を伝達し、第１の通信機１０にて補正用のプリコーディング係数を算出する方法を説明する。 <<2>> Embodiment 2
<<2-1>> Configuration In the first embodiment, it is assumed that the first and second communication devices 10 and 20, which are transceivers, have known frequency characteristics of their own acoustic devices. However, if the second communication device 20 is a smart terminal, the frequency characteristics of the acoustic signal output section and the acoustic signal input section of the smart terminal itself are not necessarily disclosed, so the above assumption does not hold. There can be cases. Therefore, in the acoustic communication system according to the second embodiment, when the second communication device 30 used as a receiver cannot acquire the frequency characteristics of its own acoustic equipment, the second communication device 30 A method of transmitting the frequency characteristic of the acoustic signal input unit 23 of the second communication device 30 to the communication device 10 and calculating the precoding coefficients for correction in the first communication device 10 will be described.
　図１０は、実施の形態２に係る音響通信システムの構成を示すブロック図である。図１０において、図１に示される構成と同一又は対応する構成には、図１に示される符号と同じ符号が付される。実施の形態２に係る音響通信システムは、第２の通信機３０の構成及び動作の点が、実施の形態に係る音響通信システムと相違する。 FIG. 10 is a block diagram showing the configuration of the acoustic communication system according to the second embodiment. In FIG. 10, the same reference numerals as those shown in FIG. 1 are attached to the same or corresponding configurations as those shown in FIG. The acoustic communication system according to the second embodiment differs from the acoustic communication system according to the embodiment in the configuration and operation of the second communication device 30. FIG.
　図１１は、実施の形態２に係る音響通信システムの第２の通信機３０の第２の信号処理部３１の構成を示すブロック図である。第２の通信機３０の第２の信号処理部３１は、周波数帯域の特性が均一なキャリブレーションデータを生成するキャリブレーションデータ生成部５０１と、音響信号入力部２３から得られた受信信号２６の接続先を決定する接続先選択部５０２と、接続先選択部５０２に接続先として選択された場合に送信信号１４の伝搬路特性を算出する伝搬路特性推定部５０３と、推定した伝搬路特性を用いて等化処理を実施する等化処理部５０４と、等化処理後の信号に復調処理を施す復調部５０５とを有している。加えて、第２の信号処理部３１は、接続先選択部５０２に接続先として選択された場合に受信信号２６を格納するデータメモリ５０６を有しており、キャリブレーションデータ生成部５０１からの出力、又はデータメモリ５０６からの読み出し信号のどちらかを音響信号出力部２２に出力する切替部５０７を有している。なお、第２の通信機３０は、動作制御信号により各モードにおける信号処理動作を制御する。 FIG. 11 is a block diagram showing the configuration of the second signal processing section 31 of the second communication device 30 of the acoustic communication system according to the second embodiment. The second signal processing unit 31 of the second communication device 30 includes a calibration data generation unit 501 that generates calibration data with uniform frequency band characteristics, and a reception signal 26 obtained from the acoustic signal input unit 23. A connection destination selection unit 502 that determines a connection destination, a propagation path characteristics estimation unit 503 that calculates the propagation path characteristics of the transmission signal 14 when the connection destination selection unit 502 selects the connection destination, and the estimated propagation path characteristics. and a demodulation unit 505 for demodulating the equalized signal. In addition, the second signal processing unit 31 has a data memory 506 that stores the received signal 26 when it is selected as a connection destination by the connection destination selection unit 502, and the output from the calibration data generation unit 501 is , or a read signal from the data memory 506 to the acoustic signal output unit 22 . The second communication device 30 controls the signal processing operation in each mode according to the operation control signal.
《２－２》動作
　図１２は、実施の形態２によるキャリブレーションモードの動作を示すフローチャートである。なお、本音響通信システムでは、キャリブレーションモード中の伝搬路特性の影響を最小限にするため、第１の通信機１０のすぐ前の位置に第２の通信機３０を固定して図１２の処理を実施することが望ましい。 <<2-2>> Operation FIG. 12 is a flow chart showing the operation of the calibration mode according to the second embodiment. In this acoustic communication system, in order to minimize the influence of the propagation path characteristics during the calibration mode, the second communication device 30 is fixed at a position immediately in front of the first communication device 10 as shown in FIG. Treatment is desirable.
　第２の通信機３０は、キャリブレーションモードが開始された後、切替部５０７の出力をキャリブレーションデータ生成部５０１からの出力信号とした上で、キャリブレーションデータ生成ステップＳ２０１にてキャリブレーションデータを生成し、音響信号出力部２２から音響送信信号２５として出力する。ここで、第２の通信機３０では、プリコーディング処理を実施していないため、音響送信信号２５には、音響信号出力部２２の周波数歪（ＲＳ）が重畳されることになる。 After the calibration mode is started, the second communication device 30 uses the output of the switching unit 507 as the output signal from the calibration data generation unit 501, and then generates the calibration data in the calibration data generation step S201. It is generated and output as an acoustic transmission signal 25 from the acoustic signal output unit 22 . Here, since precoding processing is not performed in the second communication device 30 , frequency distortion (RS) of the acoustic signal output section 22 is superimposed on the acoustic transmission signal 25 .
　次に、第１の通信機１０は、ポストコーディング係数算出ステップＳ２０２にて周波数特性メモリ１０９より音響信号入力部１３の周波数特性（ＴＭ）を読み出し、その逆特性（１／ＴＭ）をプリコーディング係数に設定する。そして、ポストコーディング処理ステップＳ２０３にて、音響信号入力部１３より得た受信信号１６に対してポストコーディング係数算出ステップＳ２０２で算出したポストコーディング係数を用いてポストコーディング処理を実施する。この処理により、受信信号１６が音響信号入力部１３を通る際に重畳されていた音響信号入力部１３の周波数歪が補正され、ポストコーディング処理後の信号の周波数特性は、音響信号出力部２２の周波数特性（ＲＳ）となる。その後、第１の通信機１０は、周波数特性推定ステップＳ２０４にてポストコーディング後の信号について周波数特性を推定し、推定結果を一時メモリに格納する。 Next, the first communication device 10 reads out the frequency characteristic (TM) of the acoustic signal input unit 13 from the frequency characteristic memory 109 in a postcoding coefficient calculation step S202, and uses its inverse characteristic (1/TM) as a precoding coefficient. set to Then, in postcoding processing step S203, postcoding processing is performed on the received signal 16 obtained from the acoustic signal input unit 13 using the postcoding coefficients calculated in the postcoding coefficient calculation step S202. This processing corrects the frequency distortion of the acoustic signal input section 13 superimposed when the received signal 16 passes through the acoustic signal input section 13, and the frequency characteristic of the signal after the postcoding process is the same as that of the acoustic signal output section 22. It becomes a frequency characteristic (RS). After that, the first communication device 10 estimates the frequency characteristic of the signal after postcoding in the frequency characteristic estimation step S204, and stores the estimation result in the temporary memory.
　さらに、第１の通信機１０は、切替部１０３の出力をキャリブレーションデータ生成部１０１からの出力信号とした上で、キャリブレーションデータ生成ステップＳ２０５にてキャリブレーションデータを生成する。 Furthermore, the first communication device 10 uses the output of the switching unit 103 as the output signal from the calibration data generation unit 101, and then generates calibration data in the calibration data generation step S205.
　次に、プリコーディング係数算出ステップＳ２０６にて、周波数特性メモリ１０９より音響信号出力部１２の周波数特性（ＴＳ）と一時メモリに格納された周波数特性（ＲＳ）を読み出し、両特性を乗算した周波数特性の逆特性（１／（ＴＳ×ＲＳ））をプリコーディング係数とする。 Next, in precoding coefficient calculation step S206, the frequency characteristic (TS) of the acoustic signal output unit 12 and the frequency characteristic (RS) stored in the temporary memory are read out from the frequency characteristic memory 109, and the frequency characteristic obtained by multiplying both characteristics is obtained. Let the inverse characteristic (1/(TS×RS)) be the precoding coefficient.
　さらに、プリコーディング処理ステップＳ２０７では、キャリブレーションデータに対してプリコーディング係数算出ステップＳ２０６にて算出した係数を用いたプリコーディング処理を実施する。第１の通信機１０は、これらの処理を実施した送信信号１４を音響信号出力部１２から音響送信信号１５として出力する。ここで、出力された音響送信信号１５の周波数特性には、音響信号出力部２２の周波数歪の逆特性（１／ＲＳ）のみが与えられた状態となる。 Furthermore, in precoding processing step S207, precoding processing using the coefficients calculated in precoding coefficient calculation step S206 is performed on the calibration data. The first communication device 10 outputs the transmission signal 14 subjected to these processes as an acoustic transmission signal 15 from the acoustic signal output unit 12 . Here, only the inverse characteristic (1/RS) of the frequency distortion of the acoustic signal output section 22 is given to the frequency characteristic of the output acoustic transmission signal 15 .
　次に、第２の通信機３０は、接続先選択部５０２の接続先をデータメモリ５０６とした上で音響送信信号１５をマイク２３にて受信し、受信信号２６をデータメモリ５０６へ格納する。そして、切替部５０７の出力をデータメモリからの読み出し信号とし、読み出し信号を音響信号出力部２２より音響送信信号２５として出力する。これらの処理により、第１の通信機１０が出力した音響送信信号１５は、第２の通信機３０の音響信号入力部２３、音響信号出力部２２を経由して返送されるため、返送される音響送信信号２５の周波数特性には、マイク２３の周波数特性（ＲＭ）が重畳されている状態となる。 Next, the second communication device 30 sets the connection destination of the connection destination selection unit 502 to the data memory 506 , receives the acoustic transmission signal 15 with the microphone 23 , and stores the reception signal 26 in the data memory 506 . Then, the output of the switching unit 507 is used as the readout signal from the data memory, and the readout signal is output as the acoustic transmission signal 25 from the acoustic signal output unit 22 . As a result of these processes, the acoustic transmission signal 15 output by the first communication device 10 is returned via the acoustic signal input section 23 and the acoustic signal output section 22 of the second communication device 30. The frequency characteristic (RM) of the microphone 23 is superimposed on the frequency characteristic of the acoustic transmission signal 25 .
　その後、第１の通信機１０は、ポストコーディング係数算出ステップＳ２０８にて、周波数特性メモリ１０９より音響信号入力部１３の周波数特性（ＴＭ）を読み出し、その逆特性（１／ＴＭ）をポストコーディング係数として設定する。ポストコーディング処理ステップＳ２０９では、音響信号入力部１３から得た受信信号１６に対してポストコーディング処理を実施する。この処理により、ポストコーディング処理後の信号には、音響信号入力部２３の周波数特性（ＲＭ）の影響が残る。次に、第１の通信機１０は、周波数特性ステップＳ２１０にてポストコーディング処理後の信号の周波数特性を推定し、推定結果を音響信号入力部２３の周波数特性とみなして周波数特性メモリ１０９に格納する。最後に、第１の通信機１０は、プリコーディング係数算出ステップＳ２１１にて、周波数特性メモリ１０９より音響信号入力部２３の周波数特性（ＲＭ）と音響信号出力部１２の周波数特性（ＴＳ）を読み出し、その逆特性を乗算した値（１／（ＲＭ×ＴＳ））をプリコーディング係数として設定する。 After that, in the postcoding coefficient calculation step S208, the first communication device 10 reads out the frequency characteristic (TM) of the acoustic signal input unit 13 from the frequency characteristic memory 109, and uses the inverse characteristic (1/TM) as the postcoding coefficient. set as In post-coding processing step S209, the received signal 16 obtained from the acoustic signal input unit 13 is subjected to post-coding processing. By this processing, the influence of the frequency characteristic (RM) of the acoustic signal input section 23 remains in the signal after the postcoding processing. Next, the first communication device 10 estimates the frequency characteristics of the post-coding signal in a frequency characteristics step S210, regards the estimation results as the frequency characteristics of the acoustic signal input unit 23, and stores them in the frequency characteristics memory 109. do. Finally, in the precoding coefficient calculation step S211, the first communication device 10 reads the frequency characteristics (RM) of the acoustic signal input section 23 and the frequency characteristics (TS) of the acoustic signal output section 12 from the frequency characteristic memory 109. , and a value (1/(RM×TS)) multiplied by its inverse characteristic is set as a precoding coefficient.
　プリコーディング係数算出ステップＳ２１１が終了した後、音響通信システムは、キャリブレーションモードが完了したとし、データ通信モードへと移行する。その後は、実施の形態１と同様にデータ通信を実施する。 After the precoding coefficient calculation step S211 ends, the acoustic communication system assumes that the calibration mode is completed, and shifts to the data communication mode. After that, data communication is performed in the same manner as in the first embodiment.
《２－３》効果
　実施の形態２によるキャリブレーションモードでは、第１の通信機１０が音響信号出力部２２の周波数特性を知った上でキャリブレーションデータに対して音響信号出力部２２の周波数歪を補正するプリコーディング処理を実施することで、音響信号出力部２２、音響信号入力部２３を通したキャリブレーションデータにおける音響信号出力部２２の周波数歪の影響を補正して第１の通信機１０に音響信号入力部２３の周波数特性のみを伝えることが可能となる。そのため、実施の形態２は、第２の通信機３０が音響信号出力部２２、音響信号入力部２３の周波数特性を取得できない状況においても第１の通信機１０が第２の通信機３０の音響信号入力部２３の周波数特性を正しく推定してプリコーディング係数に反映できる。よって、データ通信時における音響通信システムにおける復調性能を向上させることができる。 <<2-3>> Effect In the calibration mode according to the second embodiment, the frequency distortion of the acoustic signal output unit 22 is calculated with respect to the calibration data after the first communication device 10 knows the frequency characteristics of the acoustic signal output unit 22. is corrected, the influence of the frequency distortion of the acoustic signal output unit 22 in the calibration data passed through the acoustic signal output unit 22 and the acoustic signal input unit 23 is corrected, and the first communication device 10 Only the frequency characteristic of the acoustic signal input section 23 can be transmitted to the . Therefore, in the second embodiment, even in a situation where the second communication device 30 cannot acquire the frequency characteristics of the acoustic signal output unit 22 and the acoustic signal input unit 23, the first communication device 10 can reproduce the sound of the second communication device 30. The frequency characteristics of the signal input unit 23 can be correctly estimated and reflected in the precoding coefficients. Therefore, it is possible to improve the demodulation performance in the acoustic communication system during data communication.
《２－４》実施の形態２の変形例
　また、実施の形態２においても、実施の形態１の変形例１から３に記載した雑音強調の影響を低減させる方法、干渉波の影響を低減させる方法、第２の通信機２０が複数の候補となる場合に機種コードとプリコーディング係数を紐づけて保管する方法を実施することも可能である。 <<2-4>> Modification of Embodiment 2 Also in Embodiment 2, the method for reducing the influence of noise enhancement described in Modifications 1 to 3 of Embodiment 1, and the influence of interference waves are reduced. It is also possible to implement a method of linking and storing model codes and precoding coefficients when the second communication device 20 is a plurality of candidates.
　１０　第１の通信機、　１１、１１ａ、１１ｂ、１１ｃ　第１の信号処理部、　１２　音響信号出力部、　１３　音響信号入力部、　１４　送信信号、　１５　音響送信信号、　１６　受信信号、　２０、３０　第２の通信機、　２１、３１　第２の信号処理部、　２２　音響信号出力部、　２３　音響信号入力部、　２４　送信信号、　２５　音響送信信号、　２６　受信信号、　１０１　キャリブレーションデータ生成部、　１０２　送信情報生成部、　１０３　切替部、　１０４　プリコーディング処理部、　１０５　プリコーディング係数算出部、　１０６　ポストコーディング処理部、　１０７　ポストコーディング係数算出部、　１０８、１０８ａ　周波数特性推定部、　１０９　周波数特性メモリ、　１２１　時間ダイバ―シチ処理部、　１２２　時間ダイバ―シチ用データメモリ、　１３１　干渉波電力計測部、　１３２　干渉波電力メモリ、　１４１　機種コード取得部、　１４２　プリコーディング係数メモリ、　２０１　キャリブレーションデータ生成部、　２０２　プリコーディング処理部、　２０３　プリコーディング係数算出部、　２０４　接続先選択部、　２０５　ポストコーディング処理部、　２０６　ポストコーディング係数算出部、　２０７　周波数特性推定部、　２０８　伝搬路特性推定部、　２０９　等化処理部、　２１０　復調部、　２１１　周波数特性メモリ、　５０１　キャリブレーションデータ生成部、　５０２　接続先選択部、　５０３　伝搬路特性推定部、　５０４　等化処理部、　５０５　復調部、　５０６　データメモリ、　５０７　切替部。 10 first communication device, 11, 11a, 11b, 11c first signal processing unit, 12 acoustic signal output unit, 13 acoustic signal input unit, 14 transmission signal, 15 acoustic transmission signal, 16 reception signal, 20, 30 2 communication device, 21, 31 second signal processing unit, 22 acoustic signal output unit, 23 acoustic signal input unit, 24 transmission signal, 25 acoustic transmission signal, 26 reception signal, 101 calibration data generation unit, 102 transmission information Generation unit, 103 switching unit, 104 precoding processing unit, 105 precoding coefficient calculation unit, 106 postcoding processing unit, 107 postcoding coefficient calculation unit, 108, 108a frequency characteristic estimation unit, 109 frequency characteristic memory, 121 time diver - 122 Time diversification data memory 131 Interference wave power measurement unit 132 Interference wave power memory 141 Model code acquisition unit 142 Precoding coefficient memory 201 Calibration data generation unit 202 Precoding processing unit 203 precoding coefficient calculation unit 204 connection destination selection unit 205 postcoding processing unit 206 postcoding coefficient calculation unit 207 frequency characteristics estimation unit 208 propagation path characteristics estimation unit 209 equalization processing unit 210 demodulation unit 211 frequency characteristics memory, 501 calibration data generation unit, 502 connection destination selection unit, 503 propagation path characteristics estimation unit, 504 equalization processing unit, 505 demodulation unit, 506 data memory, 507 switching unit.

Claims (9)

  1. 　第１の音響信号出力部、第１の音響信号入力部、及び第１の信号処理部を有する第１の通信機と、
    　第２の音響信号出力部、第２の音響信号入力部、及び第２の信号処理部を有する第２の通信機と、
    　を有し、
    　前記第１の信号処理部は、前記第２の通信機に送信する送信情報に対して第１のプリコーディング係数を用いて第１のプリコーディング処理を行なって第１の送信信号を生成し、
    　前記第１の音響信号出力部は、デジタル信号である前記第１の送信信号をアナログ信号に変換した上で第１の音響送信信号として出力し、
    　前記第２の音響信号入力部は、前記第１の音響送信信号を受信し、前記第１の音響送信信号をデジタル信号に変換することで第２の受信信号を生成し、
    　前記第２の信号処理部は、前記第２の受信信号に復調処理を施して前記送信情報を復元し、
    　前記第１のプリコーディング処理は、前記第１の音響信号出力部の周波数特性の逆特性と前記第２の音響信号入力部の周波数特性の逆特性とを乗算した前記第１のプリコーディング係数を用いた処理である
    　ことを特徴とする音響通信システム。     a first communication device having a first acoustic signal output section, a first acoustic signal input section, and a first signal processing section;
    a second communication device having a second acoustic signal output section, a second acoustic signal input section, and a second signal processing section;
    has
    The first signal processing unit performs a first precoding process on transmission information to be transmitted to the second communication device using a first precoding coefficient to generate a first transmission signal,
    The first acoustic signal output unit converts the first transmission signal, which is a digital signal, into an analog signal and outputs it as a first acoustic transmission signal,
    The second acoustic signal input unit receives the first acoustic transmission signal and converts the first acoustic transmission signal into a digital signal to generate a second reception signal,
    The second signal processing unit restores the transmission information by performing demodulation processing on the second received signal,
    In the first precoding process, the first precoding coefficient obtained by multiplying the inverse characteristic of the frequency characteristic of the first acoustic signal output section by the inverse characteristic of the frequency characteristic of the second acoustic signal input section is calculated. An acoustic communication system characterized by processing using
  2. 　前記第１の信号処理部は、予め前記第１の通信機と前記第２の通信機との間における通信に基づいて前記第２のマイクの前記周波数特性を推定する
    　ことを特徴とする請求項１に記載の音響通信システム。     3. The first signal processing unit estimates the frequency characteristic of the second microphone in advance based on communication between the first communication device and the second communication device. 2. The acoustic communication system according to 1.
  3. 　前記第１の信号処理部は、予め決められた第１のキャリブレーションデータに対して前記第１のスピーカの周波数特性の逆特性をプリコーディング係数とするプリコーディング処理を実施することで前記第１の送信信号の生成を行い、
    　前記第１の音響信号出力部は、前記第１の送信信号を前記第１の音響送信信号として出力し、
    　前記第２の音響信号入力部は、前記第１の音響送信信号をデジタル信号に変換することで第２の受信信号を生成し、
    　前記第２の信号処理部は、前記第２の受信信号に前記第２の音響信号入力部の周波数特性の逆特性をポストコーディング係数とするポストコーディング処理を行うことで伝搬路の周波数特性を推定し、予め決められた第２のキャリブレーションデータに対して、前記伝搬路の前記周波数特性の逆特性、前記第２の音響信号出力部の周波数特性の逆特性、及び前記第２の音響信号入力部の周波数特性に基づくプリコーディング係数を用いたプリコーディング処理を実施することで第２の送信信号の生成を行い、
    　前記第２の音響信号出力部は、前記第２の送信信号を第２の音響送信信号として出力し、
    　前記第１の音響信号入力部は、前記第２の音響送信信号をデジタル信号に変換することで第１の受信信号を生成し、
    　前記第１の信号処理部は、前記第１の受信信号に前記第１の音響信号入力部の周波数特性の逆特性をポストコーディング係数とするポストコーディング処理を行うことで、前記第２の音響信号入力部の周波数特性を推定し、
    　前記第１の信号処理部は、前記第１の音響信号出力部の前記周波数特性の逆特性と、推定された前記第２の音響信号入力部の前記周波数特性の逆特性とを乗算することで前記第１のプリコーディング係数を算出する
    　ことを特徴とする請求項１又は２に記載の音響通信システム。     The first signal processing unit performs precoding processing on predetermined first calibration data using the inverse characteristic of the frequency characteristic of the first speaker as a precoding coefficient. to generate a transmission signal for
    The first acoustic signal output unit outputs the first transmission signal as the first acoustic transmission signal,
    The second acoustic signal input unit converts the first acoustic transmission signal into a digital signal to generate a second reception signal,
    The second signal processing unit estimates the frequency characteristics of a channel by performing postcoding processing on the second received signal using the inverse characteristics of the frequency characteristics of the second acoustic signal input unit as postcoding coefficients. and the inverse characteristic of the frequency characteristic of the propagation path, the inverse characteristic of the frequency characteristic of the second acoustic signal output unit, and the second acoustic signal input with respect to predetermined second calibration data Generate a second transmission signal by performing precoding processing using a precoding coefficient based on the frequency characteristics of the part,
    The second acoustic signal output unit outputs the second transmission signal as a second acoustic transmission signal,
    The first acoustic signal input unit converts the second acoustic transmission signal into a digital signal to generate a first received signal,
    The first signal processing unit performs postcoding processing on the first received signal using a postcoding coefficient that is the inverse characteristic of the frequency characteristic of the first acoustic signal input unit, thereby obtaining the second acoustic signal Estimate the frequency characteristics of the input section,
    The first signal processing unit multiplies the inverse characteristic of the frequency characteristic of the first acoustic signal output unit by the estimated inverse characteristic of the frequency characteristic of the second acoustic signal input unit. 3. The acoustic communication system according to claim 1, wherein said first precoding coefficients are calculated.
  4. 　前記第１の信号処理部は、前記第２の音響信号出力部から出力された複数の前記第２の音響送信信号をデジタル信号に変換した上で平均化処理して得られた前記第１の受信信号に前記第１の音響信号入力部の周波数特性の逆特性をポストコーディング係数とするポストコーディング処理を行うことで、前記第２の音響信号入力部の周波数特性を推定し、
    　前記第１の信号処理部は、前記第１の音響信号出力部の前記周波数特性の逆特性と、推定された前記第２の音響信号入力部の前記周波数特性の逆特性とを乗算することで前記第１のプリコーディング係数を算出する
    　ことを特徴とする請求項３に記載の音響通信システム。     The first signal processing section converts the plurality of second acoustic transmission signals output from the second acoustic signal output section into digital signals and then averages the first estimating the frequency characteristics of the second acoustic signal input unit by performing a postcoding process on the received signal using the inverse characteristic of the frequency characteristics of the first acoustic signal input unit as a postcoding coefficient;
    The first signal processing unit multiplies the inverse characteristic of the frequency characteristic of the first acoustic signal output unit by the estimated inverse characteristic of the frequency characteristic of the second acoustic signal input unit. 4. The acoustic communication system according to claim 3, wherein said first precoding coefficients are calculated.
  5. 　前記第２の信号処理部は、予め決められた第１のキャリブレーションデータを生成し、
    　前記第２の音響信号出力部は、前記第１のキャリブレーションデータを第２の音響送信信号として出力し、
    　前記第１の音響信号入力部は、前記第２の音響送信信号をデジタル信号に変換することで第１の受信信号を生成し、
    　前記第１の信号処理部は、前記第１の受信信号に前記第１の音響信号入力部の周波数特性の逆特性をポストコーディング係数とするポストコーディング処理を行うことで前記第２の音響信号出力部の周波数特性を推定し、予め決められた第２のキャリブレーションデータに対して、前記第２の音響信号出力部の前記周波数特性の逆特性、及び前記第１の音響信号出力部の周波数特性の逆特性を乗算したプリコーディング係数を用いたプリコーディング処理を実施することで前記第１の送信信号の生成を行い、
    　前記第１の音響信号出力部は、前記第１の送信信号を前記第２のキャリブレーションデータに基づく前記第１の音響送信信号として出力し、
    　前記第２の音響信号入力部は、前記第２のキャリブレーションデータに基づく前記第１の音響送信信号から第２の受信信号を生成し、
    　前記第２の音響信号出力部は、前記第２の受信信号を前記第２のキャリブレーションデータに基づく前記第２の音響送信信号として出力し、
    　前記第１の音響信号入力部は、前記第２のキャリブレーションデータに基づく前記第２の音響送信信号から前記第２のキャリブレーションデータに基づく前記第１の受信信号を生成し、
    　前記第１の信号処理部は、前記第２のキャリブレーションデータに基づく前記第１の受信信号に前記第１の音響信号入力部の周波数特性の逆特性をポストコーディング係数とするポストコーディング処理を行うことで、前記第２の音響信号入力部の周波数特性を推定し、
    　前記第１の信号処理部は、前記第１の音響信号出力部の前記周波数特性の逆特性と、推定された前記第２のマイクの前記周波数特性の逆特性とを乗算することで前記第１のプリコーディング係数を算出する
    　ことを特徴とする請求項１又は２に記載の音響通信システム。     The second signal processing unit generates predetermined first calibration data,
    The second acoustic signal output unit outputs the first calibration data as a second acoustic transmission signal,
    The first acoustic signal input unit converts the second acoustic transmission signal into a digital signal to generate a first received signal,
    The first signal processing unit outputs the second acoustic signal by performing postcoding processing on the first received signal using a postcoding coefficient that is the inverse characteristic of the frequency characteristic of the first acoustic signal input unit. estimating the frequency characteristics of the second acoustic signal output unit and the inverse characteristics of the frequency characteristics of the second acoustic signal output unit and the frequency characteristics of the first acoustic signal output unit with respect to predetermined second calibration data. Generate the first transmission signal by performing precoding processing using a precoding coefficient multiplied by the inverse characteristic of
    The first acoustic signal output unit outputs the first transmission signal as the first acoustic transmission signal based on the second calibration data,
    The second acoustic signal input unit generates a second received signal from the first acoustic transmission signal based on the second calibration data,
    The second acoustic signal output unit outputs the second reception signal as the second acoustic transmission signal based on the second calibration data,
    The first acoustic signal input unit generates the first received signal based on the second calibration data from the second acoustic transmission signal based on the second calibration data,
    The first signal processing unit performs post-coding processing on the first received signal based on the second calibration data using the inverse characteristic of the frequency characteristic of the first acoustic signal input unit as a post-coding coefficient. By estimating the frequency characteristic of the second acoustic signal input unit,
    The first signal processing unit multiplies the inverse characteristic of the frequency characteristic of the first acoustic signal output unit by the estimated inverse characteristic of the frequency characteristic of the second microphone, thereby multiplying the first 3. The acoustic communication system according to claim 1, wherein the precoding coefficients of are calculated.
  6. 　前記第１の信号処理部は、前記第２の音響信号出力部から出力された前記第２のキャリブレーションデータに基づく複数の前記第２の音響送信信号を平均化処理して得られた前記第１の受信信号に前記第１のマイクの周波数特性の逆特性をポストコーディング係数とするポストコーディング処理を行うことで、前記第２の音響信号入力部の周波数特性を推定し、
    　前記第１の信号処理部は、前記第１の音響信号出力部の前記周波数特性の逆特性と、推定された前記第２の音響信号入力部の前記周波数特性の逆特性とを乗算することで前記第１のプリコーディング係数を算出する
    　ことを特徴とする請求項４に記載の音響通信システム。     The first signal processing unit averages a plurality of the second acoustic transmission signals based on the second calibration data output from the second acoustic signal output unit. estimating the frequency characteristics of the second acoustic signal input unit by performing postcoding processing on the received signal of 1 using the inverse characteristics of the frequency characteristics of the first microphone as postcoding coefficients,
    The first signal processing unit multiplies the inverse characteristic of the frequency characteristic of the first acoustic signal output unit by the estimated inverse characteristic of the frequency characteristic of the second acoustic signal input unit. 5. The acoustic communication system according to claim 4, wherein said first precoding coefficients are calculated.
  7. 　前記第１の通信機は、
    　周囲の干渉波を計測し電力を算出する干渉波電力計測部と、
    　計測した干渉波の周波数帯と干渉波電力を格納する干渉波電力メモリと、
    　を有し、
    　前記第１の信号処理部は、前記干渉波電力メモリに、予め決められた電力値を超える干渉波電力が存在する場合、
    　前記予め決められた電力値を超える干渉波電力が発生した周波数帯を読み出し、前記周波数帯における周波数特性を、前記周波数帯の近傍の周波数帯における周波数特性を用いて補間処理することにより推定し、
    　前記補間処理が施された前記第１の受信信号に前記第１の音響信号入力部の周波数特性の逆特性をポストコーディング係数とするポストコーディング処理を行うことで、前記第２の音響信号入力部の周波数特性を推定する
    　ことを特徴とする請求項３から６のいずれか１項に記載の音響通信システム。     The first communication device is
    an interference wave power measurement unit that measures surrounding interference waves and calculates power;
    an interference wave power memory that stores the frequency band and interference wave power of the measured interference wave;
    has
    When interference wave power exceeding a predetermined power value exists in the interference wave power memory, the first signal processing unit
    reading out the frequency band in which the interference wave power exceeding the predetermined power value occurs, and estimating the frequency characteristics in the frequency band by interpolation processing using the frequency characteristics in the frequency band in the vicinity of the frequency band;
    post-coding the interpolated first received signal using the inverse characteristic of the frequency characteristic of the first acoustic signal input unit as a post-coding coefficient, thereby obtaining the second acoustic signal input unit. The acoustic communication system according to any one of claims 3 to 6, wherein the frequency characteristic of is estimated.
  8. 　前記第２の通信機となり得る複数の候補通信機が存在し、前記複数の候補通信機は異なる機種コードを有している場合、
    　前記第１の信号処理部は、
    　前記機種コードと前記第１のプリコーディング係数とを紐づけて保管するプリコーディング係数メモリと、
    　前記機種コードを取得する機種コード取得部と、
    　を有し、
    　前記機種コード取得部が取得した前記機種コードに基づいて前記第１のプリコーディング係数を設定する
    ことを特徴とする請求項１から７のいずれか１項に記載の音響通信システム。     When there are a plurality of candidate communication devices that can be the second communication device, and the plurality of candidate communication devices have different model codes,
    The first signal processing unit is
    a precoding coefficient memory that associates and stores the model code and the first precoding coefficient;
    a model code acquisition unit that acquires the model code;
    has
    The acoustic communication system according to any one of claims 1 to 7, wherein the first precoding coefficient is set based on the model code acquired by the model code acquisition unit.
  9. 　第１の音響信号出力部、第１の音響信号入力部、及び第１の信号処理部を有する第１の通信機と、
    　第２の音響信号出力部、第２の音響信号入力部、及び第２の信号処理部を有する第２の通信機と、
    　を有する音響通信システムが実施する音響通信方法であって、
    　前記第１の信号処理部が、前記第２の通信機に送信する送信情報に対して第１のプリコーディング係数を用いて第１のプリコーディング処理を行なって第１の送信信号を生成するステップと、
    　前記第１の音響信号出力部が、前記第１の送信信号を第１の音響送信信号として出力するステップと、
    　前記第２の音響信号入力部が、前記第１の音響送信信号を受信し、前記第１の音響送信信号をデジタル信号に変換することで第２の受信信号を生成するステップと、
    　前記第２の信号処理部が、前記第２の受信信号に復調処理を施して前記送信情報を復元するステップと、
    　を有し、
    　前記第１のプリコーディング処理は、前記第１の音響信号出力部の周波数特性の逆特性と前記第２の音響信号入力部の周波数特性の逆特性とを乗算した前記第１のプリコーディング係数を用いた処理である
    　ことを特徴とする音響通信方法。     a first communication device having a first acoustic signal output section, a first acoustic signal input section, and a first signal processing section;
    a second communication device having a second acoustic signal output section, a second acoustic signal input section, and a second signal processing section;
    An acoustic communication method performed by an acoustic communication system having
    the first signal processing unit performing a first precoding process using a first precoding coefficient on transmission information to be transmitted to the second communication device to generate a first transmission signal; When,
    a step in which the first acoustic signal output unit outputs the first transmission signal as a first acoustic transmission signal;
    the second acoustic signal input receiving the first acoustic transmission signal and converting the first acoustic transmission signal into a digital signal to generate a second reception signal;
    the second signal processing unit performing demodulation processing on the second received signal to restore the transmission information;
    has
    In the first precoding process, the first precoding coefficient obtained by multiplying the inverse characteristic of the frequency characteristic of the first acoustic signal output section by the inverse characteristic of the frequency characteristic of the second acoustic signal input section is calculated. An acoustic communication method characterized by processing using
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JP2015524180A (en) * 2012-05-09 2015-08-20 ハンガー ４ プロジェクトス エルティーディーエー Data transmission method between devices by sound wave
WO2020235078A1 (en) * 2019-05-23 2020-11-26 日本電信電話株式会社 Optical transmission system and compensation method
WO2020235627A1 (en) * 2019-05-22 2020-11-26 Ｎｔｔエレクトロニクス株式会社 Optical transmission characteristics compensating method and optical transmission characteristics compensating system

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JP2002527926A (en) * 1998-10-02 2002-08-27 コムセンス・テクノロジーズ・リミテッド How to use acoustic signals for computer communication
JP2015524180A (en) * 2012-05-09 2015-08-20 ハンガー ４ プロジェクトス エルティーディーエー Data transmission method between devices by sound wave
WO2020235627A1 (en) * 2019-05-22 2020-11-26 Ｎｔｔエレクトロニクス株式会社 Optical transmission characteristics compensating method and optical transmission characteristics compensating system
WO2020235078A1 (en) * 2019-05-23 2020-11-26 日本電信電話株式会社 Optical transmission system and compensation method

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