JP2015231055A - Transmission device and reception device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmission device and a reception device that enables execution of processing at a specific timing at a reception side in a mechanism of transmitting data by using a sound transmission medium.SOLUTION: An acoustic transmission system has at least a transmission device 1 for superimposing information on an acoustic signal and emitting sounds, and a reception device 2 for collecting the sounds and extracting the information. The transmission device 1 divides a frame containing a command and Elapse time into plural blocks and transmits the blocks on a frequency-band basis. The reception device 2 demodulates these blocks to obtain the command and the Elapse Time, and executes the processing specified by the command at a specified timing by the Elapse Time. Accordingly, the processing can be executed at a specific timing at the reception side in a mechanism for transmitting data by using a sound as a medium for transmitting sounds.

Description

  The present invention relates to a technique for transmitting data using sound (sound wave) as a transmission medium.

  A technique for transmitting data using an acoustic signal or sound (sound wave) as a transmission medium is known. In this type of technology, a mechanism for superimposing data only on sounds belonging to a specific frequency band that cannot be heard by humans is conceivable. For example, in a data transmission environment where there is a lot of reverberant sound (reflected sound). In some cases, data such as multipath fading and noise may not be able to be extracted from the sound.

JP 2010-288246 A JP 2006-251676 A

  Here, as shown in FIG. 10, on the transmission side, 1 / n of a period required to transmit one frame composed of three blocks a, b, and c in each of different frequency bands F1, F2, and F3. A mechanism is assumed in which transmission of each frame is started while being delayed by a period corresponding to (1/3 in the figure). For example, in the frequency band F1, transmission of the first block a of the frame is started at time t6, transmission of the block a is started at time t5 in the frequency band F2, and transmission of block a is started at time t4 in the frequency band F3. Start. Then, on the receiving side, for example, the block b1 and the block c1 that have been received in the frequency bands F2 and F1 different from the block a1 are selected starting from the block a1 that has been received at the time point t0 (procedure 1 in the figure). In this procedure 1, since each block is selected one by one from all frequency bands in one block transmission period, the period required for the reception device 2 to collect the sound on which transmission data for one frame is superimposed is One block transmission period is sufficient. However, when the block c2 cannot be received due to the influence of multipath fading or the like, on the receiving side, for example, the block b1 that has been received in the frequency band F2 different from the block a1, and the time point one block before the time point t7 At time t6, the block c2 that has been received in the same frequency band F3 as the block a1 is selected (procedure 2). That is, in this procedure 2, each block is selected from a plurality of frequency bands in an arbitrary combination in a period longer than one block transmission period and shorter than a period required for transmission of one frame.

  As described above, in the mechanism shown in FIG. 10, since a plurality of frequency bands are used, resistance to multipath fading and the like (so-called robustness) is improved, but the reception completion timing of one frame consisting of a, b, and c is improved. Becomes undefined. For this reason, it is not suitable for a usage scene in which, for example, a frame transmitted from the transmission side is used to instruct the reception side to execute a certain process at a specific timing.

  Accordingly, an object of the present invention is to provide a mechanism for executing processing at a specific timing on the receiving side in a mechanism for transmitting data using sound as a transmission medium.

In order to solve the above-described problem, the transmission device according to the present invention relates to processing designation information that designates processing to be executed by the receiving device, and the elapsed time from the time of reception by the receiving device to the timing to execute the processing. Different frequency bands based on division means for dividing a frame including timing specifying information for specifying timing for executing processing into a plurality of blocks, and on each block obtained by dividing a frame including the different elapsed time into a plurality of blocks Modulation signal generating means for generating a modulated signal obtained by modulating the carrier wave a plurality of times before the timing for executing the processing arrives, and sound emitting means for emitting a sound corresponding to the generated modulated signal.
The receiving device according to the present invention includes a sound collecting unit that collects the sound emitted from the transmitting device, and a modulated acoustic signal corresponding to the sound collected by the sound collecting unit in different frequency bands. Designated by separating means for separating, frame generating means for generating a frame composed of blocks obtained by demodulating the modulated acoustic signal for each of the separated frequency bands, and the processing designation information included in the generated frame Processing execution means for executing the processed processing at a timing designated by the timing designation information.

  According to the present invention, in a mechanism for transmitting data using sound as a transmission medium, processing can be executed at a specific timing on the receiving side.

The block diagram which shows the structural example of the acoustic transmission system which concerns on one Embodiment of this invention. Block diagram showing a hardware configuration example of a modulation unit of a transmission device or a demodulation unit of a reception device Block diagram showing a functional configuration example of the modulation unit of the transmission device (A) A diagram showing an example of a frame structure of data, (b) a diagram conceptually showing a relationship between a frame and a block. Conceptual diagram for explaining frame transmission timing Conceptual diagram for explaining the relationship between frame transmission timing and event generation timing Flow chart showing processing procedure of transmitting apparatus The block diagram which shows the structural example of the demodulation part of a receiver Flow chart showing processing procedure of receiving apparatus Conceptual diagram for explaining frame transmission timing in robust mode

[1. Outline of acoustic transmission system]
An acoustic transmission system according to an embodiment of the present invention is a system that transmits and receives information to be transmitted using sound (sound wave) as a transmission medium. The acoustic transmission system includes at least a transmission device that emits sound by superimposing information on an acoustic signal, and a reception device that collects the sound and extracts information. Since the sound emission of the sound on which information is superimposed corresponds to the transmission of information, it is expressed below that the transmission device transmits information as necessary. Moreover, since the sound collection of the sound on which the information is superimposed corresponds to the reception of the information, it is expressed below that the receiving device receives the information as necessary.

This acoustic transmission system is used, for example, in the following scenes (1) to (3), but is not necessarily limited to these examples.
(1) Information for causing a receiving device such as a smartphone possessed by a user to execute a certain process at a specific timing from a transmission device installed in a place where a plurality of users are present such as a road or a store. Is superimposed on the sound and transmitted, and the receiving apparatus performs processing at a timing according to the information.
(2) A television device in the house functions as a transmission device, and a receiving device such as a smart phone or a personal computer used by the user from the television device executes a certain process in synchronization with the television program, for example. Information is superimposed on the sound and transmitted, and the receiving apparatus performs processing at a specific timing synchronized with the television program.
(3) One of portable devices such as smart phones possessed by each of a plurality of users functions as a transmission device and the other functions as a reception device. For example, the transmission device causes the reception device to execute a certain process. The information is superimposed on the sound and transmitted, and the receiving device performs processing at a specific timing.
In the above scenes (1) to (3), the information to be transmitted may be superimposed on the sound in the non-audible range, and further may be superimposed on the music or sound belonging to the audible range such as background music. Alternatively, the music and sound in the audible range may not exist, and the information to be transmitted may be superimposed only on the sound in the non-audible range.
In the following description, performing a specified process at a timing specified by the transmitting apparatus in the receiving apparatus is referred to as “event occurrence”.

[2. Overall configuration of acoustic transmission system]
FIG. 1 is a block diagram illustrating a configuration example of an acoustic transmission system. Here, for the sake of simplicity, the minimum configuration of the transmission device 1 and the reception device 2 is illustrated, but the transmission device 1 and the reception device 2 may each have a configuration other than that illustrated. Good.

  The transmission device 1 is an example of a transmission device according to the present invention, and includes a modulation unit 10, an output unit 11, and a speaker 12. The modulation unit 10 is an example of a modulation device according to the present invention, and is a unit that modulates a carrier wave having a high frequency band with transmission data D to be transmitted and superimposes it on the acoustic data S. The high band here is a frequency band higher than the upper limit (about 10 to 20 kHz) of the frequency band of sound that can be heard by humans. For example, in the case of the above (2), the acoustic data S is the sound or music of a television program, and the transmission data D is subjected to certain processing at a specific timing in accordance with the content of the television program in the receiving device 2. This is information to specify. For example, the acoustic data S and the transmission data D may be stored in a storage medium in the transmission device 1 or may be supplied to the transmission device 1 from the outside of the transmission device 1. . The output unit 11 includes a D / A converter that converts the digital signal output from the modulation unit 10 into an analog signal, and an amplifier that amplifies the analog signal output from the D / A converter and supplies the analog signal to the speaker 12. The speaker 12 is a sound emitting unit that emits a sound corresponding to the analog signal input from the output unit 11. The emitted sound propagates through space (atmosphere) and is collected by the microphone 20 of the receiving device 2.

  The receiving device 2 is an example of a receiving device according to the present invention, and includes a microphone 20, an input unit 21, a demodulation unit 22, a control device 23, and a control target 24. The microphone 20 is a sound collection unit that collects sound emitted from the speaker 12 and outputs an acoustic signal corresponding to the sound. The input unit 21 includes an amplifier that amplifies an acoustic signal output from the microphone 20 and an A / D converter that converts an analog acoustic signal output from the amplifier into a digital signal. The demodulator 22 is an example of a demodulator according to the present invention, and demodulates the transmission data D from the digital signal output from the A / D converter. The transmission data D is a bit string composed of “1” or “0”, and is input to the control device 23. The control device 23 includes a microprocessor, a RAM (Random Access Memory), and the like, and is a process execution unit that executes a process specified by the transmission data D at a timing specified by the transmission data D. The control target includes, for example, an output device that outputs information based on the transmission data D as an image or sound, a toy or a device / mechanism called a gadget that operates based on the transmission data D, and the like.

  Each structure of the modulation | alteration part 10 and the demodulation part 22 may be implement | achieved by hardware, and may be implement | achieved when hardware and software cooperate. When the configuration of the modulation unit 10 is realized by cooperation of hardware and software, the hardware of the modulation unit 10 is configured as a computer, for example, as shown in FIG. In this case, as illustrated in FIG. 2, the modulation unit 10 includes at least a control unit 1000 including a microprocessor and a RAM, and a storage unit 1001 that is a large-capacity storage such as a hard disk. Each configuration (described later) of the modulation unit 10 is realized by the microprocessor of the control unit 1000 reading the program stored in the storage unit 1001 into the RAM and executing the read program. Further, the hardware of the demodulation unit 22 when the configuration of the demodulation unit 22 is realized by the cooperation of hardware and software is also a configuration as shown in FIG. In this case, each configuration (described later) of the demodulating unit 22 is realized by the microprocessor of the control unit 1000 reading the program stored in the storage unit 1001 into the RAM and executing the read program.

[3. Configuration of modulation unit in transmission apparatus]
FIG. 3 is a diagram illustrating a configuration example of the modulation unit 10 of the transmission device 1. The modulation unit 10 includes an LPF 101 as a processing system for the acoustic data S, and includes a division unit 104, LPFs 1021 to 1023, a VCO (Voltage-controlled oscillator) 1031 to 1033, and an adder 105 as a processing system for the transmission data D. The LPF 101 is connected to the adder 105. The LPFs 1021 to 1023 are connected to the dividing unit 104 and also connected to the adder 105 via the VCOs 1031 to 1033.

  The LPF 101 removes high-band frequency components from the acoustic data S. The cut-off frequency of the LPF 101 is, for example, an upper limit value of an audible frequency band (about 10 to 20 kHz) so as to ensure sound quality of the acoustic data S by the listener and to secure a band used for modulation (referred to as a modulation band). ) Is set to a degree. This cutoff frequency becomes the lower limit frequency of the modulation band. For example, if the cut-off frequency of the LPF 101 is made too low, the sound quality of the sound data S at the time of sound emission is deteriorated, and if the frequency of the modulation band is lowered in accordance with the low cut-off frequency, it belongs to this modulation band. This is because the sound when the modulated signal is emitted is likely to be attached to the listener's ear. Conversely, if the cut-off frequency of the LPF 101 is too high, the modulation band cannot be widened, and the transmission speed of transmission data decreases. The signal output from the LPF 101 is input to the adder 105.

  In the transmission apparatus 1, one frame is divided into n units (n is a positive integer, in this embodiment, n = 3 as an example), and transmitted in this divided unit. This divided unit is called a block. Here, FIG. 4A shows an example of the structure of this frame. One frame F is composed of a header including information on frame attributes such as a frame length, a payload including actual data, and a footer corresponding to the rear end of the frame in order from the top. The payload includes a command that is process designation information that designates a process to be executed in the reception apparatus 2 and an Elapse Time that is timing designation information that designates a timing at which the reception apparatus 2 executes the process. FIG. 4B is a diagram conceptually showing the relationship between frames and blocks. As shown in FIG. 4B, one frame is composed of three blocks a, b, and c having an equal data length.

  The dividing unit 104 of the modulation unit 10 illustrated in FIG. 3 is a dividing unit that divides one frame into a plurality of (here, three) blocks. Each of the LPFs 1021 to 1023 is a filter for removing a frequency component corresponding to a high band in order to limit the band of the baseband signal, and is called a Nyquist filter. The Nyquist filter is generally composed of an FIR filter called a cosine roll-off filter. The order of the filter, the roll-off rate, and the like are determined according to application conditions. The transmission data D is filtered by the LPFs 1021 to 1023 and then input to the VCOs 1031 to 1033 to generate a modulation signal. In the adder 105, the modulation signal based on the transmission data D and the acoustic signal based on the acoustic data S are added. The LPFs 1021 to 1023, the VCOs 1031 to 1033, and the adder 105 constitute modulation signal generation means. The acoustic signal to which the modulation signal has been added is supplied to the output unit 11, and a sound based on the acoustic signal to which the modulation signal has been added is emitted from the speaker 12.

  Here, FIG. 5 is a conceptual diagram for explaining the transmission timing of each block. FIG. 6 is a conceptual diagram for explaining the relationship between the frame transmission timing and the event generation timing. In FIG. 5, the notation “a” means block a, the notation “b” means block b, and the notation “c” means block c. F1, F2, and F3 mean frequency bands of carrier waves of transmission data. As shown in FIG. 5, the transmission apparatus 1 transmits blocks a1, b1, and c1 that constitute one frame in each of different frequency bands F1, F2, and F3 by time t4. For example, the first block a1 of the frame is transmitted in the frequency band F1, the block b1 is transmitted in the frequency band F2, and the block c1 is transmitted in the frequency band F3. As shown in FIG. 6, the payload of the frame composed of these blocks a1, b1, and c1 includes the elapsed time from the reception completion time t4 of these blocks (that is, one frame) in the receiving device 2 to the event occurrence time t0. “4000ms” is described as Elapse Time. The receiving device 2 demodulates these blocks a1, b1, and c1 to obtain a command and Elapse Time, and executes a process specified by this command at a timing specified by this Elapse Time.

The transmission device 1 generates and transmits a plurality of frames having the same command and different Elapse Times until the timing for executing the process (event occurrence time point) arrives. For example, by time t3, the transmission device 1 transmits blocks a2, b2, and c2 constituting one frame in each of the different frequency bands F1, F2, and F3, and by time t2, the transmission device 1 is different. In each of the frequency bands F1, F2, and F3, blocks a3, b3, and c3 constituting one frame are transmitted, and by the time point t1, the transmission apparatus 1 has 1 in each of the different frequency bands F1, F2, and F3. Blocks a4, b4 and c4 constituting one frame are transmitted. As shown in FIG. 6, in the payload of the frame composed of blocks a2, b2, and c2, “3000 ms” that is an elapsed time from the reception completion time t3 of these blocks to the event occurrence time t0 is described as Elapse Time. . In the payload of the frame composed of the blocks a3, b3, and c3, “2000 ms” that is an elapsed time from the reception completion time t2 to the event occurrence time t0 is described as Elapse Time. In the payload of the frame composed of the blocks a4, b4, and c4, “1000 ms” that is an elapsed time from the reception completion time t1 to the event occurrence time t0 is described as Elapse Time.
Thus, the transmission device 1 improves the communication success rate by performing frame transmission a plurality of times (here, four times) with a time interval before an event occurs. In the example of FIG. 6, three out of four frame transmissions have failed, but since one has succeeded, the acoustic communication itself has succeeded.

  FIG. 7 is a flowchart showing a processing procedure in the transmission apparatus 1. First, the modulation unit 10 acquires transmission data D (frame) (step S11). The Elapse Time in the transmission data D at the time when the dividing unit 104 obtains is blank. Next, the modulation unit 10 subtracts the time required for frame transmission / reception as a delay time (for example, 0.7 seconds) from the time from the current time to the event occurrence time, obtains an Elapse Time, and describes it in the frame ( Step S12). Next, the modulation unit 10 divides the frame into three (step S13), and after performing modulation processing for each frequency band (step S14), transmits the frame (step S15).

[4. Configuration of demodulation unit in receiving apparatus]
FIG. 8 is a block diagram illustrating a configuration example of the demodulation unit 22 of the reception device 2. The demodulation unit 22 includes a bit decoding unit 220 and a data detection unit 230. The bit decoding unit 220 receives an acoustic signal collected by the microphone 20 and A / D converted by the input unit 21. Since the acoustic signal input at this time includes an acoustic signal corresponding to the transmission data D modulated by the transmission apparatus 1, the acoustic signal input to the bit decoding unit 220 is referred to as a modulated acoustic signal A. . The bit decoding unit 220 converts the acoustic signal corresponding to the transmission data D out of the input modulated acoustic signal A into binary data “1” or “0”, decodes the bit value, and the data detection unit 230. To output. The data detection unit 230 extracts transmission data D from the binary data output from the bit decoding unit 220. Hereinafter, the details of these parts will be described.

  The bit decoding unit 220 includes an HPF 221, an STFT unit 222, subtracters 2231 to 2233, DC cut units 2251 to 2253, and binarization units 2261 to 2263. The HPF 221 removes a low-band signal component corresponding to the acoustic data S from the input modulated acoustic signal A, and extracts a high-band signal component corresponding to the transmission data D. That is, the cutoff frequency of the HPF 221 is set to the lower limit frequency of the modulation band.

  The STFT unit 222 is a separation unit that separates the signal output from the HPF 221 into signal components belonging to the frequency bands f1, f2, and f3 used at the time of transmission. Specifically, the STFT unit 222 performs a short-time Fourier transform (STFT) on the signal output from the HPF 221, and applies the signal components belonging to the frequency bands F1, F2, and F3 described above. Separate and output a time-varying waveform of each signal component. At this time, the overlap rate in the short-time Fourier transform is 50%, that is, the STFT unit 222 performs STFT with half overlap. For example, the FFT length is 1024 samples, the 1-symbol sample length is 1536 samples, and the sampling frequency after STFT is 86.1328125 Hz. One symbol sample length is, for example, 1 time, 1.5 times, 2 times the FFT length, but is 1.5 times in this embodiment. The sampling frequency after STFT is calculated from the FFT length and the overlap rate.

  The LPFs 2241 to 2243 remove signal components corresponding to the high band and extract signal components in the frequency band to which the baseband signal belongs. Note that the LPFs 1021 to 1023 of the transmission apparatus 1 and the LPFs 2241 to 2243 of the reception apparatus 2 are configured to be complete Nyquist filters.

  The DC cut units 2251 to 2253 are provided corresponding to the frequency bands F1, F2, and F3, and extract a baseband signal from the signals output from the LPFs 2241 to 2243. Specifically, the DC cut units 2251 to 2253 perform the process of correcting the envelope on the signals output from the LPFs 2241 to 2243 (referred to as envelope processing), thereby removing the DC offset and extracting the baseband signal. To do.

The binarization units 2261 to 2263 binarize the baseband signal using the threshold th, decode the bit value, and output the decoded bit value to the data detection unit 230.
The data detection unit 230 extracts transmission data from the bit data output from the binarization units 2261 to 2263. Then, the data detection unit 230 outputs a frame generated through decoding and error detection as transmission data.

  FIG. 9 is a flowchart illustrating a processing procedure in the reception device 2. First, the demodulator 22 of the receiving device 2 acquires an acoustic modulation signal (step S21). The demodulator 22 supplies the transmission data obtained by demodulating it to the control device 23 (step S22). The control device 23 refers to a timer as its own time measuring means and determines whether or not Elapse Time has elapsed (step S23). If the Elapse Time elapses (step S23; Yes), the control device 23 executes the process specified by the transmission data command (step S24).

  According to the embodiment described above, in a mechanism for transmitting data using sound as a transmission medium, it is possible to execute processing at a specific timing on the receiving side.

[Modification]
[Modification 1: Combined use with robust mode]
The above embodiment is an embodiment in which processing timing is emphasized, and is referred to as a trigger mode here. On the other hand, the mechanism shown in FIG. 10 is intended to improve robustness, and is referred to herein as a robust mode. The sound transmission system may switch between the trigger mode and the robust mode. The robust mode will be described below. FIG. 10 is a conceptual diagram for explaining conditions when a frame is generated by extracting a block in the robust mode. In FIG. 10, a1, b1, b2, c1, and c2 are the same blocks as a, b, and c respectively represented by the same alphabet, but 1 or 2 for easy understanding of the description of the selected block. It was distinguished by appending the number. The time interval between t0 and t6 is a period required for reception of one block (1/3 of a period required for transmission of one frame, hereinafter referred to as one block transmission period). It is assumed that the current time is time t0, and the blocks received by the receiving device 2 in each frequency band F1, F2, F3 up to time t0 are stored in a storage unit (not shown) of the receiving device 2.

  The transmitting apparatus 1 has a predetermined period, that is, a period required for transmitting one frame (a period in which one frame is superimposed in a certain frequency band) in each of the different frequency bands F1, F2, and F3. Transmission of each frame is started while being delayed by a period corresponding to n (for example, 1/3). For example, in the frequency band F1, transmission of the first block a of the frame is started at time t6, transmission of the block a is started at time t5 in the frequency band F2, and transmission of block a is started at time t4 in the frequency band F3. Has started. Accordingly, the transmission start timing of the next frame after the frame is always the transmission period of one frame, such as time t3 in the frequency band F1, time t2 in the frequency band F2, and time t1 in the frequency band F3. Delay by a period corresponding to 1/3. Therefore, “1/3 of the period required for transmitting one frame” described above corresponds to the length of the period required for transmitting one block.

  The data detection unit 230 starts from the block a that has been received at the time point t0, that is, the first block (block a1 in the figure) of one frame, and the remaining blocks b and c necessary to form the frame. Are selected according to a predetermined selection method. The predetermined selection method includes four procedures described below. If the data detection unit 230 attempts to decode the frame and detect an error in the order of the procedure 1 to the procedure 4 and can correctly demodulate the transmission data for one frame in a certain procedure, the data detection unit 230 processes the subsequent procedures. Do not do.

  Procedure 1: At the time t0 when reception of the block a1 is completed, the block b1 and the block c1 that have been received in the frequency bands F2 and F1 different from the block a1 are selected (block a1, block b1, Block c1). That is, in this procedure 1, one block is selected from each of all frequency bands in one block transmission period. Therefore, the period required for the reception device 2 to collect the sound with the transmission data for one frame superimposed is only one block transmission period.

  Procedure 2: At time t0 when reception of the block a1 is completed, the block b1 that has been received in a frequency band F2 different from the block a1, and the same frequency band F3 as the block a1 at time t1 one block before the time t0 The block c2 for which reception has been completed is selected. That is, in this procedure 2, each block is selected from a plurality of frequency bands in an arbitrary combination in a period longer than one block transmission period and shorter than a period required for transmission of one frame.

  Procedure 3: Block b2 that has been received in the same frequency band F3 as block a1 at time t2 two blocks before time t0, and the same frequency band as block a1 at time t1 one block before time t0 The block c2 that has been received in F3 is selected (block a1, block b2, and block c2 surrounded by dotted lines in the figure). That is, in this procedure 3, each block is selected from one frequency band in a period required for transmission of one frame.

  Procedure 4: The block b2 that has been received in the same frequency band F3 as the block a1 at the time t2 that is two blocks before the time t0, and the frequency band F1 that is different from the block a1 at the time t0 when the reception of the block a1 is completed The block c1 for which reception has been completed is selected. That is, in this procedure 4, each block is selected from an arbitrary combination from a plurality of frequency bands in a period required for transmission of one frame. Procedure 4 is adopted when the influence of multipath fading and noise mixing on one of the frequency bands is greater than that of Procedure 3.

  Assuming that all the blocks a, b, and c are ready at time t0 after the start of data detection, the substantial time required for data detection in step 1 is t0-t1 (that is, one frame is required for transmission). 1/3 of the period). Therefore, in the procedure 1, when all the blocks constituting one frame are successfully detected, the substantial transmission rate is the highest among the procedures 1 to 4. That is, the period required for the microphone 20 to collect the sound in which these blocks are superimposed is the shortest.

  Next, when the data detection is successful in the procedure 2, the substantial time required for the data detection is t0-t2 (that is, 2/3 of the period required for transmitting one frame). Therefore, the procedure 2 has a substantial transmission rate after the procedure 1.

  When data detection is successful in steps 3 and 4, the substantial time required for data detection is t0-t3 (that is, the same period as that required for transmission of one frame). Therefore, when data detection is successful in procedures 3 and 4, the actual transmission rate is the lowest. That is, the period required for the microphone 20 to collect the sound in which these blocks are superimposed is the longest. Procedures 3 and 4 can suppress the effects of multipath fading and noise mixing, but the transmission rate does not change compared to the case where a single frequency band is used.

  Therefore, if there is no multipath fading or the like that adversely affects transmission quality, the period required to transmit one frame is 1 of the period required to transmit one frame without dividing it in the shortest frequency band. / 3 period will be sufficient. Even if transmission quality is expected to deteriorate due to such an adverse effect, in the present embodiment, if a period required to transmit one frame without dividing it in the frequency band is long, There is a high possibility that one frame can be transmitted. Trying to decode a frame and detect an error by selecting a block in the order from step 1 to step 4 means that the period required for the microphone 20 to pick up the sound on which the block to be selected is superimposed is more important. It means that priority is given to shortening. That is, the data detection unit 230 selects a block according to an algorithm that shortens the period required to collect the sound on which the selected block is superimposed.

[Modification 2: Omission of various filters]
In the configuration of the demodulating unit 22, the HPF 221 is used, but when the signal belonging to the band other than the modulation band is not included in the modulated acoustic signal A or when the influence can be ignored, the filtering by the HPF is performed. It does not have to be. Similarly, the LPFs used in the modulation unit 10 and the demodulation unit 22 are unnecessary when the influence of not having them can be ignored.

[Modification 3: Number of blocks and number of frequency bands]
In the embodiment, the number of blocks constituting the frame is 3, but the number is not necessarily limited thereto. Further, although the number of frequency bands F1, F2, and F3 used for modulation is three, it is not necessarily limited thereto.
In addition, when the number of blocks is larger than the number of frequency bands, the substantial transmission rate of transmission data decreases. On the other hand, when the number of frequency bands is larger than the number of blocks, the frequency bands are left over, resulting in a redundant configuration. The number of blocks and the number of frequency bands do not have to be the same as long as such a decrease in transmission rate and a redundant configuration are allowed. For example, the number of blocks constituting one frame may be six, and the number of frequency bands used for modulation may be three. It is arbitrary how the number of blocks constituting one frame and the number of frequency bands used for modulation are determined.

[Modification 4: Sound propagation medium]
In the above embodiment, the atmosphere is assumed as a medium through which sound propagates. However, in addition to gases other than the atmosphere, solids such as buildings, structures, and furniture, and liquids such as water may be used. When the medium through which the sound propagates is solid, the transmission device 1 includes a vibration unit that generates vibration according to the signal output from the output unit 11 instead of the speaker 12, while the reception device 2 is connected to the microphone 20. Instead, vibration detection means such as an acceleration sensor for detecting solid vibration is provided. In addition, when sound is generated from a solid that vibrates by the vibration means of the transmission device 1, the reception device 2 only needs to include the microphone 20 as in the embodiment.

[Modification 5: Aspects of acoustic data and transmission data]
In the above embodiment, transmission data including Elapse Time is superimposed on acoustic data in real time. However, transmission data including Elapse Time is superimposed on acoustic data in advance and supplied to the transmitter 1. Also good.

[Modification 6: Aspects of acoustic data and transmission data]
The control device 23 may give priority to the content of the frame received later in time when a frame having different Elapse Time with the same command is received a plurality of times on the receiving device 2 side. That is, when the contents of the first and second frames are different in the receiving apparatus 2, the contents of the last frame are followed. Since the situation related to the event occurrence may change suddenly on the transmission device 1 side and the event occurrence time may be finely corrected, the idea is to give priority to the last frame.

[Modification 7: Aspects of acoustic data and transmission data]
When receiving a different frame including a different command, the control device 23 performs management at the time of event occurrence for each command. In this way, it is possible to set and execute a plurality of processes in parallel in the receiving device 2.

[Modification 8: Program]
The present invention can also be specified as a program for causing a computer to realize functions equivalent to those of the transmission device 1 and the reception device 2 and a recording medium such as an optical disk storing such a program. The program according to the present invention can be provided in the form of being downloaded to a computer via a network such as the Internet, and being made available after being installed.

DESCRIPTION OF SYMBOLS 1 Transmitter, 2 Receiver, 10, 10a Modulator, 11 Output, 12 Speaker, 20 Microphone, 21 Input, 22, 22a, 22b, 22c, 22d Demodulator, 101, 1021-1023, 2241-2243 LPF , 1031 to 1033 VCO, 104 division unit, 105, 2231 to 2233 adder, 220 bit decoding unit, 221 HPF, 222 STFT unit, 2251 to 2253 DC cut unit, 2261 to 2263, 2261-1 to 2263-1 binary value Conversion unit, 230 data detection unit, 23 control device, 24 control target.

Claims (2)

A frame including process designation information for designating a process to be executed by the receiving apparatus, and timing designation information for designating a timing for executing the process by an elapsed time from a reception time by the receiving apparatus to a timing for executing the process Dividing means for dividing the block into a plurality of blocks;
A modulated signal that generates a modulated signal obtained by modulating a carrier wave of a different frequency band based on each block obtained by dividing a frame including different elapsed times into a plurality of times until the timing for executing the processing arrives A transmission device comprising: generation means; and sound emission means for emitting sound according to the generated modulation signal. Sound collection means for collecting the sound emitted from the transmission device according to claim 1;
Separating means for separating the modulated acoustic signals according to the sound collected by the sound collecting means into different frequency bands;
Frame generating means for generating a frame composed of blocks obtained by demodulating the modulated acoustic signal for each of the separated frequency bands;
A receiving apparatus comprising: a process executing unit configured to execute a process specified by the process specifying information included in the generated frame at a timing specified by the timing specifying information.

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