JP2014029406A - Information transmission device, information transmission program, information reception device, information reception program, and information communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an information transmission device, an information transmission program, an information reception device, an information reception program and an information communication method for enabling sound wave information communication that is hardly affected by noise while suppressing sound quality deterioration of sound.SOLUTION: An information transmission device 100 performs amplitude modulation of a carrier wave signal of a mosquito band being a frequency band difficult to hear regardless of being included in a human audible band on the basis of information to be transmitted, and transmits the information by outputting the carrier wave signal subjected to the amplitude modulation from a speaker 110. An information reception device 200 receives sound of a human audible band with a microphone, extracts the amplitude of the carrier wave signal being a frequency component of the mosquito band from the received sound, and recovers the information on the basis of the extracted amplitude.

Description

  The present invention relates to an information transmission apparatus, an information transmission program, an information reception apparatus, an information reception program, and an information communication method for transmitting information by sound waves.

  Non-Patent Document 1 discloses a method of transmitting information by transforming an OFDM modulated signal obtained by modulating information by OFDM (Orthogonal Frequency Division Multiplexing) so as not to be uncomfortable to hearing and superimposing it on speech / music. It is disclosed. In this method, an OFDM modulated signal obtained by modulating a subcarrier having a frequency in the human audible band with a transmission signal is generated, and the power of the subcarrier is adjusted by matching the OFDM modulated signal with the spectrum envelope of the original sound source. The OFDM modulation signal is modified so as not to be uncomfortable.

Y. Matsumoto, two others, “Sonic Information Transmission Technology in the Audible Band”, IEICE Technical Report, IEICE, EA 2006-24, p. 25-29

In the method described in Non-Patent Document 1 described above, phase modulation is used to suppress the influence on the sound in the audible band. However, since the phase of sound is more susceptible to noise than amplitude, the method described in Non-Patent Document 1 has a problem that it is vulnerable to noise.
On the other hand, although the amplitude is strong against noise, the amplitude of sound has a large effect on the sound quality felt when heard by humans. End up.

  Accordingly, the present invention provides an information transmission device, an information transmission program, an information reception device, and an information transmission device that enable sound wave information communication that is less susceptible to noise while suppressing the effect on sound quality that is perceived by a human being. It is an object to provide a receiving program and an information communication method.

(1) The present invention provides a signal processing unit that performs amplitude modulation on a carrier signal in a specific band that is included in a human audible band but is difficult to hear, based on information to be transmitted, and a human audible band An audible sound output unit capable of outputting the sound of the audible sound, wherein the audible sound output unit outputs the carrier wave signal amplitude-modulated by the signal processing unit as the sound of the specific band, thereby obtaining the information. This is an information transmission device for transmission.
According to the present invention, information is carried on a carrier wave signal by amplitude modulation, so that it is not easily affected by noise. In addition, since it is difficult for humans to listen to sound in a specific band, it is possible to suppress the influence of communication on human hearing. Moreover, the output part for outputting a sound should just be what can output the sound of the audible band widely marketed, and can suppress manufacturing cost.

(2) A synthesizer for synthesizing the carrier wave signal subjected to amplitude modulation to a sound signal (music signal or the like) to be listened to by a human, and the audible sound output unit is listened to by a human It is preferable to output a signal obtained by synthesizing the carrier signal that has been subjected to amplitude modulation to the sound signal. Since sound in a specific band is difficult to be heard by humans, even if the carrier wave signal subjected to amplitude modulation is synthesized with a sound signal (music signal, etc.) to be heard by humans, Sound quality deterioration of sound signals (music signals, etc.) can be suppressed.

(3) The sound signal in which the signal component in the specific band in the sound signal to be heard by a human is attenuated, and the synthesis unit attenuates the signal component in the specific band by the filter In addition, it is preferable to synthesize the carrier wave signal subjected to amplitude modulation. In this case, the sound signal to be heard by a human can be suppressed from becoming noise with respect to the carrier wave signal subjected to amplitude modulation.

(4) The signal processing unit may adjust the phase of the carrier wave signal subjected to amplitude modulation so as to reduce a difference between the maximum value and the minimum value of the amplitude of the carrier wave signal subjected to amplitude modulation. preferable.
In this case, the difference between the maximum value and the minimum value of the amplitude of the carrier wave signal can be reduced. When outputting sound, the power of the entire sound needs to be below a certain level. When a carrier signal is output together with other sound signals in an audible band other than a specific band, the maximum and minimum amplitudes of the carrier signal If the difference from the value is large, it is necessary to suppress the amplitude (dynamic range) of other sound signals so that the power of the entire sound is not saturated at the maximum value. For this reason, with the above configuration, the dynamic range of the other sound signal can be increased.

(5) It is preferable that the signal processing unit is configured to adjust the phase of the carrier signal x (t) according to the equations (1) to (3).

Here, N represents a positive integer, s (n) represents the amplitude of the carrier signal, θ (n) represents the phase of the carrier signal, and fc represents the fundamental frequency of the carrier signal.
In the Schroeder phase given by the equations (1) to (3), it is possible to minimize the difference between the maximum value and the minimum value of the amplitude in the waveform. Therefore, with the above configuration, the difference between the maximum value and the minimum value of the amplitude of the carrier wave signal can be made as small as possible.

(6) Preferably, the signal processing unit is configured to perform amplitude modulation on the carrier wave signal while compensating that the sound pressure level indicated by the sound pressure frequency characteristic of the audible sound output unit differs depending on the frequency. .
Depending on the audible sound output unit, the sound pressure level in a high frequency region, particularly in a specific band, may be lower than the sound pressure level in other frequency bands. With the above configuration, the sound pressure frequency characteristic of the audible sound output unit can be compensated.

(7) It further includes an identification signal generation unit for generating an identification signal for identifying whether or not the information exists in a range where the information can be received, and the identification signal is a signal within the specific band. Preferably, the identification signal generation unit generates the identification signal regardless of whether there is information to be transmitted other than the identification signal.
In this case, since the receiving side can easily determine whether or not information can be received by receiving the identification signal, convenience is improved.

(8) The signal processing unit is configured to allocate information to be transmitted to a plurality of frequencies in the specific band, and to modulate the amplitude of each carrier signal of each frequency based on the allocated information. preferable.
In this case, since there are a plurality of carrier wave signals, a large amount of information can be transmitted at a time.

(9) According to another aspect of the present invention, a computer having an audible sound output unit capable of outputting sounds in a human audible band includes a specific band that is included in the human audible band but is difficult to hear. A step of performing amplitude modulation on the carrier wave signal based on information to be transmitted, and outputting the carrier wave signal subjected to amplitude modulation by the signal processing unit as sound of the specific band from the audible sound output unit, And an information transmission program for executing the step of transmitting the information.

(10) Further, the present invention from another viewpoint is included in the human audible band from the audible sound input unit that can input the sound of the human audible band and the sound received by the audible sound input unit. Is an information receiving device comprising: a signal analysis unit that extracts the amplitude of a frequency component in a specific band that is a frequency band that is difficult to listen to, and restores information based on the extracted amplitude.

  According to the present invention, since information is acquired from an amplitude-modulated carrier wave signal, it is less susceptible to noise. In addition, since it is difficult for human beings to listen to sound in a specific band, it is possible to suppress the influence of communication on human hearing. The audible sound input unit may be anything that can input sound in the audible band that is widely marketed, and the information receiving device is configured using a smartphone, a mobile phone, or other portable information terminal equipped with a microphone. Can do.

(11) The signal analysis unit includes an identification signal for identifying whether or not the information receiving side is present in the specific band of the sound received by the audible sound input unit within a range where the information can be received. Receivable information indicating that the information exists in a receivable range when the signal analyzing unit determines that the identification signal is included. It is preferable to further include a display unit that displays the receivability information when the signal analysis unit determines that the receivability identification signal is not included.
In this case, since the user can easily determine whether or not information can be received based on whether or not the receivable information is displayed, convenience is improved.

(12) Furthermore, according to another aspect of the present invention, a computer having an audible sound input unit capable of inputting a sound of a human audible band is used to generate a human audible band from the sound received by the audible sound input unit. Is an information receiving program for executing the steps of extracting the amplitude of a frequency component of a specific band that is a frequency band that is difficult to listen to, and restoring the information based on the extracted amplitude .

(13) Further, according to another aspect of the present invention, the step of performing amplitude modulation on a carrier signal in a specific band, which is a frequency band included in a human audible band but difficult to hear, based on information to be transmitted And transmitting the information by outputting the amplitude-modulated carrier wave signal from an audible sound output unit capable of outputting a sound in a human audible band; and receiving a sound in a human audible band And extracting the amplitude of the carrier wave signal, which is a frequency component of the specific band, from the received sound, and restoring the information based on the extracted amplitude.

  According to the present invention, it is possible to perform sound wave information communication that is less susceptible to noise while suppressing the effect of communication on human hearing.

The schematic diagram which shows the whole structure of the sound wave information communication system which concerns on embodiment. The functional block diagram which shows the structure of the information transmitter which concerns on embodiment. The functional block diagram which shows the detailed structure of a signal processing part. The graph which shows an example of the relationship between the frequency and power of sound signal data. The graph which shows the audio | voice waveform after removing a mosquito band component from the sound signal data shown to FIG. 4A. The graph for demonstrating the signal which synthesize | combined sound signal data and the carrier wave signal. The graph which shows the bit string in a packet, and the definition of the information linked | related with each bit. The graph which shows a speaker characteristic. The schematic diagram which shows the audio | voice waveform at the time of outputting the audio | voice signal of a fixed level with a speaker in each frequency. The schematic diagram for demonstrating the characteristic compensation of a speaker. The graph which shows the time waveform of the audio | voice signal obtained by giving a zero phase. The graph which shows the time waveform of the audio | voice signal obtained by giving a random phase. The graph which shows the time waveform of the audio | voice signal obtained by giving a Schroeder phase. The block diagram which shows the structure of the information transmitter which concerns on embodiment. The functional block diagram which shows the structure of the information receiver which concerns on embodiment. The block diagram which shows the structure of the information receiver which concerns on embodiment. The flowchart which shows the operation | movement procedure of the information transmitter which concerns on embodiment. The flowchart which shows the operation | movement procedure of the information receiver which concerns on embodiment.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

[1. Overall Configuration of Sonic Information Communication System]
FIG. 1 is a schematic diagram showing an overall configuration of a sound wave information communication system according to the present embodiment. The sound wave information communication system 1 according to the present embodiment includes an information transmission device 100 and a plurality of information reception devices 200, 200, 200. The information transmitting apparatus 100 includes a speaker 110 that is an audible sound output unit.
The speaker 110 of the information transmitting apparatus 100 is for outputting a sound in a human audible band, and outputs a normal sound signal (music signal or the like) to be heard by a human such as music, and also transmits information ( It is possible to output a signal for data transmission.
The audible sound is captured by a microphone included in the information receiving devices 200, 200, 200, and the information receiving device 200 extracts information from the sound (audible sound) received by the microphone, and displays the information on the screen. It has become.
The sound wave information communication system is suitably used for outputting a normal sound signal to be listened to by a human such as music and transmitting information related to the sound signal (for example, music lyrics information).

[2. Configuration of information transmission apparatus]
FIG. 2 is a functional block diagram showing a configuration of the information transmitting apparatus according to the present embodiment. The information transmitting apparatus 100 includes a sound source data storage unit 101 that stores sound source data, a low-pass filter 102, an information storage unit 103, an encoder 104, a signal processing unit 105, a service area signal generation unit 106, and a synthesis unit 107. A D / A converter 108, an amplifier 109, and a speaker 110.

  The sound source data storage unit 101 stores sound signal data (music data or the like) intended to be listened to by a person such as music. Sound signal data is read from the sound source data storage unit 101 and output to the low-pass filter 102. Note that the sound source data storage unit 101 may exist outside the information transmission apparatus 100.

The low pass filter 102 is a filter for removing high frequency components included in the sound signal data. FIG. 4A shows an example of the relationship between the frequency and power of sound signal data. The sound signal data is data indicating the sound of the human audible band. In addition to signal components in a band that can be easily heard by humans (for example, a band of 17 kHz or less), a band that is difficult for humans to hear (hereinafter referred to as “mosquito”). The signal component of “band” is included.
The mosquito band (specific band) is, for example, a band of about 17.4 kHz to 22.05 kHz in the audible band. A more preferable lower limit of the mosquito band is 19 kHz from the viewpoint that human listening becomes more difficult. Since a mosquito sound having a frequency of about 17.4 kHz may be audible to a young person, conventionally, the mosquito sound having such a frequency has been used for the purpose of giving unpleasant feeling to the young person. However, when importance is attached to listening difficulty, it is preferable that the frequency be slightly higher (for example, 19 kHz or higher) than the frequency of a general mosquito sound (about 17.4 kHz).
A more preferable upper limit of the mosquito band is 21 kHz, and a more preferable upper limit is 20 kHz.
The low-pass filter 102 is used to attenuate signal components in the mosquito band (specific band) from the sound signal data. 4B shows the frequency spectrum of the audible sound after removing the mosquito band component from the sound signal data shown in FIG. 4A. As shown in FIG. 4B, the low-pass filter 102 removes the mosquito band component from the sound signal data. Thereby, it can prevent that a sound signal becomes noise with respect to the communication signal (carrier wave signal) using a mosquito band.
The filter 102 only needs to be a filter for attenuating signal components in the mosquito band (specific band), and is not limited to a low-pass type. A cut filter may be used.

  The information storage unit 103 stores information to be transmitted by sonic information communication (hereinafter referred to as “embedded information”). The embedded information read from the information storage unit 103 is given to the encoder 104. The embedded information may be given to the information transmission apparatus 100 from outside the information transmission apparatus 100.

  The encoder 104 encodes the embedded information into a digital signal according to a predetermined rule. The embedded information after conversion by the encoder 104 is given to the signal processing unit 105.

  The signal processing unit 105 performs amplitude modulation on the carrier signal (carrier) in the mosquito band based on the given embedded information, and places the embedded information on the carrier signal. FIG. 3 is a functional block diagram showing a detailed configuration of the signal processing unit 105. As illustrated in FIG. 3, the signal processing unit 105 includes an amplitude setting unit 151, a phase adjustment unit 153, and an inverse fast Fourier transform unit 154. The amplitude setting unit 151 is supplied with data from the speaker characteristic storage unit 152.

The embedded information output from the encoder 104 is first given to the amplitude setting unit 151. The amplitude setting unit 151 divides the received embedded information into 8 bits. FIG. 5 is a graph showing a bit string in a packet and the definition of information associated with each bit. In FIG. 5, the vertical axis represents signal power, and the horizontal axis represents frequency. As shown in FIG. 5, information transmitting apparatus 100 according to the present embodiment transmits information by frequency division multiplexing in which 11-bit information is transmitted together by 11 carrier signals (subcarriers).
Of the 11-bit information, 8 bits are used as a data signal, and the remaining 3 bits are used as a control signal. A signal including this 11-bit information is defined as a packet. That is, the information transmitting apparatus 100 generates a packet including 8-bit data from the embedded information, and transmits the packet superimposed on the sound signal data. Therefore, the amplitude setting unit 151 divides the embedded information into 8 bits.
In this embodiment, a single carrier signal (subcarrier) represents a 1-bit signal (0 or 1) depending on the amplitude, but a single carrier signal may represent a multi-bit signal. Good.

  Each of the 3-bit control signals included in the packet includes a trigger 1 signal, a trigger 2 signal, and a condition signal. Each of the trigger 1 signal and the trigger 2 signal is used to indicate that a packet is being transmitted. That is, the trigger 1 signal is a control signal for transmitting a first transmission identification flag indicating that a packet is being transmitted, and the trigger 2 signal is a second transmission identification flag indicating that a packet is being transmitted. Is a control signal for transmitting. In the packet, either the first transmission identification flag in the trigger 1 signal or the second transmission identification flag in the trigger 2 signal is always turned on. That is, when the first transmission identification flag is on in the trigger 1 signal of a packet, the second transmission identification flag is off in the trigger 2 signal of the packet. Conversely, when the first transmission identification flag is off in the trigger 1 signal of a packet, the second transmission identification flag is on in the trigger 2 signal of the packet. Therefore, when one of the first transmission identification flag and the second transmission identification flag is on and the other is off, it can be determined that the information is a packet.

  In two packets sent in succession, the flag to be turned on is switched between the first transmission identification flag and the second transmission identification flag. That is, when the first transmission identification flag is turned on and the second transmission identification flag is turned off in the packet transmitted before, the first transmission identification flag is turned off in the packet transmitted later, The second transmission identification flag is turned on. On the other hand, when the first transmission identification flag is turned off and the second transmission identification flag is turned on in the packet transmitted before, the first transmission identification flag is turned on in the packet transmitted later. And the second transmission identification flag is turned off. In this way, by switching the first transmission flag and the second transmission flag alternately and turning them on, it is possible to determine packet switching on the reception side. Further, when both the first transmission flag and the second transmission flag of the same packet are on or both are off at the receiving side, the frame including the packet is ignored.

  The condition signal is used to indicate a start packet and an end packet. That is, the condition signal is a control signal for transmitting a start / end flag indicating the start and end of a packet. In the start packet, the start / end flag in the condition signal is turned on, and in the 8-bit data signal, information identifying whether the packet is the start or end, and information to be transmitted is lyrics, title, Information indicating the type of information, such as a URL, is transmitted. The end packet gives the receiving side the display timing of the embedded information. That is, on the receiving side, a series of packets from the start packet to the end packet is received, and when the end packet is received, the embedded information transmitted in the series of packets is displayed.

  In packets other than the start packet and the transmission packet (hereinafter referred to as “data packet”), the start / end flag is turned off in the condition signal, and the embedded information is transmitted in the data signal. When generating a data packet, the amplitude setting unit 151 further divides the embedded information divided into 8 bits for packet transmission into 1-bit units. The amplitude setting unit 151 assigns the information of each bit to the frequency (carrier wave signal) of the data signal in the mosquito band. That is, 8-bit embedded information is assigned to each of the eight frequencies for each bit. Each of the eight data signals is amplitude modulated based on the assigned bits.

  The speaker characteristic storage unit 152 stores information indicating the frequency characteristic (sound pressure frequency characteristic) of the speaker 110. Based on this frequency characteristic (hereinafter referred to as “speaker characteristic”), the amplitude setting unit 151 performs speaker characteristic compensation when amplitude-modulating the data signal.

The speaker characteristic compensation will be described below. FIG. 6A is a graph showing speaker characteristics, and FIG. 6B is a schematic diagram showing an audio waveform when an audio signal having a constant level is output from the speaker at each frequency. 6A, the vertical axis represents the power (sound pressure) of the sound output of the speaker 110, and the horizontal axis represents the frequency. As shown in FIG. 6A, some speakers may have a characteristic that the output level in the mosquito band is lower than the output level in the audible band other than the mosquito band. That is, the output power (sound pressure) of the speaker 11 may differ depending on the frequency. Ideally, the characteristic of FIG. 6A should be flat even in the mosquito band.
As shown in FIG. 6B, when a sound signal having a constant power is output at each frequency using a speaker having such characteristics, the signal in the mosquito band is attenuated along the envelope of the speaker characteristics shown in FIG. 6A. . That is, the amplitude of the carrier signal (subcarrier) that transmits information by amplitude modulation is distorted regardless of the content of the information. In such a case, it is conceivable that a demodulation error of embedded information embedded in the mosquito band occurs on the receiving side.

  In order to solve this problem, in the characteristic compensation of the speaker, the signal level in the mosquito band is compensated based on the speaker characteristic. FIG. 6C is a schematic diagram for explaining the characteristic compensation of the speaker. As shown in FIG. 6C, in the speaker characteristic compensation, the signal level is increased using the inverse of the power of the sound output of the speaker characteristic of each frequency as a coefficient. As a result, the power of the signal in the mosquito band with a low output level is increased. When this sound signal is output from the speaker, the output level of each frequency becomes appropriate as shown in the right diagram of FIG. 6C. Thus, it is possible to suppress the demodulation error of the embedded information. Inexpensive speakers often exhibit such characteristics, and thus the characteristic compensation of such speakers is particularly effective when using inexpensive speakers.

In the amplitude setting unit 151 of the present embodiment, information is embedded depending on the presence or absence of power in the mosquito band. That is, only the amplitude information of the carrier signal in the mosquito band is used for information communication, and the phase information of the carrier signal is not used for information communication.
Therefore, an arbitrary phase can be given to the carrier wave signal in the mosquito band. Therefore, in the present embodiment, the carrier wave signal in the mosquito band that has been amplitude-modulated by the amplitude setting unit 151 is supplied to the phase adjustment unit 153. The phase adjustment unit 153 is for adjusting the phase of the carrier signal so as to reduce the difference between the maximum value and the minimum value of the amplitude of the carrier signal.

  The phase adjustment of the carrier wave signal will be described below. When outputting sound, the power of the entire sound must be below a certain level, and when the carrier signal is output together with other sounds in the audible band other than the mosquito band, the maximum and minimum amplitudes of the carrier signal If the difference is large, it is necessary to suppress the amplitude of other sounds so that the power of the entire sound is not saturated at the maximum value. That is, in the case of signals having the same energy, it is preferable to minimize the difference between the maximum value and the minimum value of the amplitude.

In order to meet this requirement, in this embodiment, a Schroeder phase is added to a signal to adjust the phase of the signal and minimize the difference between the maximum value and the minimum value of the amplitude. When the phase of the carrier wave signal is also used for information transmission (when not only amplitude modulation but also phase modulation is performed), phase adjustment by the phase adjustment unit 153 cannot be performed.
Here, the Schroeder phase will be described. The Schroeder phase θ (n) is given by the following expression when the input waveform x (t) is a periodic signal having a fundamental frequency f _c Hz.

N is a positive integer, and s (n) is the amplitude of the carrier signal.

  In order to calculate the Schroeder phase, s (n) is given a value from n = 1, but s (n) = 0 in n other than the 11-bit section used in the present embodiment.

  7A is a graph showing a time waveform of a signal obtained by giving a zero phase, FIG. 7B is a graph showing a time waveform of a signal obtained by giving a random phase, and FIG. 7C shows a Schroeder phase. It is a graph which shows the time waveform of the signal obtained by giving. 7A to 7C, the vertical axis indicates the amplitude of the signal, and the horizontal axis indicates time. 7A to 7C show results of phase adjustment of signals having the same energy. As shown in FIG. 7A, a periodic peak is observed in a signal with a zero phase added, that is, no phase adjustment, and therefore the difference between the maximum and minimum amplitudes compared to the other two. Is getting bigger. The dynamic range of this signal was 14.5. Next, as shown in FIG. 7B, the difference between the maximum value and the minimum value of the signal with the random phase, that is, the signal with the phase adjusted at random, is smaller than that of the signal with the zero phase. The difference between the maximum value and the minimum value of the amplitude was larger than that of the signal with phase. The dynamic range of this signal was 11.8. Further, as shown in FIG. 7C, the difference between the maximum value and the minimum value of the amplitude was the smallest in the signal to which the Schroeder phase was added, that is, the phase was adjusted according to the above equations (1) to (3). The dynamic range of this signal was 8.4.

  The carrier wave signal whose phase has been adjusted by the phase adjustment unit 153 is given to the inverse fast Fourier transform unit 154. The inverse fast Fourier transform unit 154 performs inverse fast Fourier transform on the given plurality of carrier signals.

The service area signal generation unit 106 is a reception availability identification signal for identifying whether the information reception device 200 exists in a range where the information transmitted from the information transmission device 100 can be received (hereinafter referred to as “service area”). (Hereinafter referred to as “service area signal”).
As shown in FIG. 5, this service area signal is a signal different from the frequency of the carrier signal (data signal and control signal) having information to be transmitted, but the frequency within the mosquito band (hereinafter referred to as “service area”). Frequency)).
This service area signal is a signal having a specific amplitude at the service area frequency.
The service area signal generation unit 106 always generates a service area signal regardless of the presence / absence of information other than the service area signal to be transmitted (information output from the encoder 104 and given to the signal processing unit 105).

  The sound signal data from which the mosquito band component has been removed by the low-pass filter 102, the carrier wave signal subjected to the inverse fast Fourier transform by the inverse fast Fourier transform unit 154, and the service area signal generated by the service area signal generation unit 106 are synthesized. To the unit 107. The synthesizing unit 107 is for synthesizing the sound signal data, the carrier wave signal, and the service area signal. FIG. 4C is a diagram for explaining a signal obtained by synthesizing sound signal data and a carrier wave signal. As described above, the mosquito band component is removed from the sound signal data by the low-pass filter 102. In the synthesis unit 107, a carrier signal (embedded information) in the mosquito band is added to the sound signal data. Although not shown in FIG. 4C, a service area signal is also added to the sound signal data. The service area signal is output from the synthesizing unit 107 regardless of the presence / absence of a sound signal output from the low-pass filter 102 or the sound source data storage unit 101 and the presence / absence of a carrier wave signal output from the signal processing unit 105. .

  The synthesized sound signal is output from the synthesis unit 107 to the D / A converter 108. The D / A converter 108 is for converting a sound signal, which is a digital signal, into an analog sound signal.

  The sound signal of the analog signal output from the D / A converter 108 is given to the amplifier 109. The amplifier 109 is for amplifying the sound signal.

  The sound signal amplified by the amplifier 109 is given to the speaker 110. The speaker 110 can output sound in an audible band including a mosquito band. The speaker 110 reproduces a sound signal and outputs a sound.

  Next, the hardware configuration of the information transmission apparatus 100 will be described. FIG. 8 is a block diagram showing a configuration of information transmitting apparatus 100 according to the present embodiment. The information transmitting apparatus 100 is realized by a computer 100a. As shown in FIG. 8, the computer 100 a includes a main body 121, a display unit 122, an input device 123, and a speaker 110. The main body 121 includes a CPU 131, ROM 132, RAM 133, hard disk 134, reading device 135, input / output interface 136, and image output interface 137. The CPU 131, ROM 132, RAM 133, hard disk 134, reading device 135, input / output interface 136, The image output interface 137 is connected by a bus 138.

  The CPU 131 can execute a computer program loaded in the RAM 133. Then, when the CPU 131 executes the information transmission program 139, the computer 100a functions as the information transmission apparatus 100.

  The ROM 132 is configured by a mask ROM, PROM, EPROM, or the like, and stores a computer program executed by the CPU 131, data used for the same, and the like.

  The RAM 133 is configured by SRAM, DRAM, or the like. The RAM 133 is used for reading the information transmission program 139 recorded on the hard disk 134. Further, when the CPU 131 executes a computer program, it is used as a work area for the CPU 131.

  The hard disk 134 is installed with various computer programs to be executed by the CPU 131 such as an operating system and application programs, and data used for executing the computer programs. An information transmission program 139 is also installed in the hard disk 134.

  The reading device 135 is configured by a flexible disk drive, a CD-ROM drive, a DVD-ROM drive, or the like, and can read a computer program or data recorded on the portable recording medium 140. In addition, the portable recording medium 140 stores an information transmission program 139 for causing the computer to function as the information transmission apparatus 100. The computer 100a reads the information transmission program 139 from the portable recording medium 140, and the information The transmission program 139 can be installed on the hard disk 134.

  The information transmission program 139 is not only provided by the portable recording medium 140 but also from an external device that is communicably connected to the computer 100a through an electric communication line (whether wired or wireless). It is also possible to provide it through a line. For example, the information transmission program 139 is stored in the hard disk of a server computer on the Internet. The computer 100a can access the server computer, download the computer program, and install it on the hard disk 134. It is.

  When the CPU 131 executes the information transmission program 139, the CPU 131 has the above-described low-pass filter 102, encoder 104, signal processing unit 105 (amplitude setting unit 151, phase adjustment unit 153, and inverse fast Fourier transform unit 154), service area signal. It functions as the generation unit 106 and the synthesis unit 107.

  On the hard disk 134, for example, a multitask operating system such as Windows (registered trademark) manufactured and sold by US Microsoft Corporation is installed. In the following description, the information transmission program 139 according to the present embodiment is assumed to operate on the operating system.

  The storage area of the hard disk 134 stores the sound signal data, embedded information, and information indicating the frequency characteristics of the speaker 110. That is, the hard disk 134 functions as the sound source data storage unit 101, the information storage unit 103, and the speaker characteristic storage unit 152.

  The input / output interface 136 is, for example, a serial interface such as USB, IEEE1394, or RS-232C, a parallel interface such as SCSI, IDE, or IEEE1284, and an analog interface including a D / A converter, an A / D converter, or the like. It is configured. An input device 123 including a keyboard and a mouse is connected to the input / output interface 136, and the user can input data to the computer 100 a by using the input device 123. A speaker 110 is connected to the input / output interface 136. The D / A converter 108 and the amplifier 109 described above are provided in the input / output interface 136.

  The image output interface 137 is connected to the display unit 122 configured by an LCD, a CRT, or the like, and outputs a video signal corresponding to the image data given from the CPU 131 to the display unit 122. The display unit 122 displays an image (screen) according to the input video signal.

[3. Configuration of information receiving apparatus]
FIG. 9 is a functional block diagram showing the configuration of the information receiving apparatus according to the present embodiment. The information receiving apparatus 200 includes a microphone 201, an amplifier 202, an A / D converter 203, a buffer 204, a fast Fourier transform unit 205, a plurality of amplitude detection units 206, 206,..., And a plurality of bit determination units. 207, 207,..., An information restoration unit 208, a decoder 209, and a display unit 210.

  A microphone (audible sound input unit) 201 can input sound in a human audible band including a mosquito band. The sound output by the information transmitting apparatus 100 is received by the microphone 201 and converted into a sound signal that is an analog signal.

  The sound signal captured by the microphone 201 is given to the amplifier 202. The amplifier 202 is for amplifying the sound signal.

  The sound signal amplified by the amplifier 202 is given to the A / D converter 203. The A / D converter 203 is for converting a sound signal which is an analog signal into a digital sound signal.

  The digital sound signal output from the A / D converter 203 is stored in the buffer 204. The buffer 204 is a storage unit capable of storing information, and is for temporarily storing a sound signal.

  The sound signal stored in the buffer 204 is given to the fast Fourier transform unit 205. The fast Fourier transform unit 205 performs fast Fourier transform on the given sound signal.

  The sound signal converted into the frequency domain representation by the fast Fourier transform unit 205 is given to each amplitude detection unit 206. In information receiving apparatus 200 according to the present embodiment, twelve amplitude detectors 206 are provided. Each amplitude detector 206 is associated with one frequency of the mosquito band. That is, the frequency of the three control signals, the frequency of the eight data signals, and the frequency of one service area signal are associated with the amplitude detectors 206, 206,.

  The amplitude detection unit 206 extracts the associated frequency component from the sound signal and detects the amplitude of the frequency component. That is, each amplitude detection unit 206 extracts three control signals, eight data signals, and one service area signal, and detects the amplitude of each signal.

  The amplitude of the signal detected by each amplitude detection unit 206, 206,... Is given to each of the 12 bit determination units 207, 207,. .. And the bit determination units 207, 207,... Have a one-to-one correspondence, and the amplitude detected by the amplitude detection unit 206 is given to the corresponding bit determination unit 207. It has become. The bit determination unit 207 compares the given amplitude with a predetermined threshold, and whether the amplitude exceeds the predetermined threshold (bit is set) or whether the amplitude does not exceed the predetermined threshold (whether the bit is not set) ). The bit determination unit 207 outputs “1” when the amplitude exceeds a predetermined threshold, and outputs “0” when the amplitude does not exceed the predetermined threshold.

  The determination result of each bit determination unit 207, 207,... The information restoring unit 208 receives data “1” or “0”, which is the determination result of the bit determining units 207, 207,..., And combines these data to restore digital data.

  The digital data restored by the information restoration unit 208 is given to the decoder 209. The decoder 209 determines the value of the flag of each control signal, and determines whether the received data is a packet, a start packet, an end packet, or a data packet. Further, when the start / end flag is on, it is determined from the data of the data signal whether it is a start packet or an end packet, and it is determined whether the transmitted information is lyrics, a title, or a URL.

  When the received data is a data packet, the decoder 209 decodes the digital data of the data signal according to a predetermined rule. That is, the decoder 209 corresponds to the encoder 104, and generates embedded information before encoding from given data (encoded data).

  Further, the decoder 209 can receive, from the output data of the bit determination unit 207 corresponding to the service area frequency, whether or not the information receiving device 200 exists in the service area, that is, the embedded information superimposed on the sound signal. It is possible to determine whether or not. That is, when the output data of the bit determination unit 207 corresponding to the service area frequency is “1”, the decoder 209 determines that the embedded information can be received, and the output of the bit determination unit 207 corresponding to the service area frequency. When the data is “0”, the decoder 209 determines that the embedded information cannot be received.

  The decoder generates a screen from the decoded information and the determination result, and causes the display unit 210 to output the screen. That is, the display unit 210 displays lyrics, titles, URLs, embedded information reception availability information, and the like.

  Next, the hardware configuration of the information receiving apparatus 200 will be described. FIG. 10 is a block diagram showing a configuration of information receiving apparatus 200 according to the present embodiment. The information receiving apparatus 200 is realized by a smartphone, a mobile phone, or other portable information terminal, that is, a portable computer 200a. As illustrated in FIG. 10, the portable information terminal 200 a includes a processor 221, a storage device 222, a wireless communication interface 223, an input device 224, a microphone 201, and a display unit 210. The processor 221, the storage device 222, the wireless communication interface 223, the input device 224, the microphone 201, and the display unit 210 are connected via the bus 5 so that data communication is possible.

  The processor 221 is an integrated circuit in which a CPU is integrated with a semiconductor memory, an input / output interface, and an image output interface. The processor 221 has the functions of the amplifier 202, the A / D converter 203, and the buffer 204 described above.

  The storage device 222 includes a flash memory that is a nonvolatile storage device. In the external storage device 222, various computer programs to be executed by the CPU 221 such as an operating system and application programs, and data used for executing the computer programs are installed. An information receiving program 225 is also installed in the external storage device 222.

  Note that the information receiving program 225 is provided through the electric communication line from an external device that is communicably connected to the portable information terminal 200a via an electric communication line (whether wired or wireless). For example, the information receiving program 225 is stored in an external storage device of a server computer on the Internet, and the portable information terminal 200a accesses the server computer to download the computer program, which is stored in the storage device 222. To install.

  When the processor 221 executes the information receiving program 225, the processor 221 has the above-described fast Fourier transform unit 205, amplitude detection units 206, 206,..., Bit determination units 207, 207,. Function as.

  In the storage device 222, for example, a multitask operating system such as an iOS manufactured and sold by Apple Inc. or an Android (registered trademark) OS manufactured and sold by Google Inc. is installed. In the following description, the information receiving program 225 according to the present embodiment is assumed to operate on the operating system.

  The display unit 210 is configured by an LCD and is connected to the processor 221. The display unit 210 displays an image (screen) according to the video signal given from the processor 221.

  The input device 224 is configured by a touch panel attached to the display unit 210. In other words, the display unit 210 and the input device 224 constitute a touch panel. By using the input device 224, the user can input data to the portable information terminal 200a.

  The microphone 210 is connected to the processor 221. The microphone 210 gives the received sound (sound) to the processor 221.

  The wireless communication interface 223 is a communication interface for performing wireless communication according to a wireless communication standard such as IEEE802.11 or W-CDMA. The portable information terminal 200a can transmit and receive data to and from other external devices via the wireless communication interface 223.

[4. Operation of information transmitting apparatus]
Next, the operation of the sound wave information communication system 1 according to the present embodiment will be described. First, the operation of the information transmitting apparatus 100 will be described.

  FIG. 11 is a flowchart showing an operation procedure of information transmitting apparatus 100 according to the present embodiment. The user of the information transmission apparatus 100 causes the CPU 131 to execute the information transmission program 139, thereby causing the computer 100a to function as the information transmission apparatus 100.

  When the information transmission program 139 is activated, the CPU 131 first generates a service area signal (step S101). Next, the CPU 131 determines whether or not an information transmission instruction has been received from the user (step S102). If the information transmission instruction has not been received (NO in step S102), the service area signal is used as the mosquito band sound signal. Are output to the speaker 110 (step S103). After the process of step S103, the CPU 131 returns the process to step S101. As a result, the service area signal is continuously transmitted even when music or the like is listened to by humans and the target signal is not output, and the user (information receiving side) It is possible to grasp whether or not it exists.

  By operating the input device 123, the user can designate music or the like to which information such as lyrics is transmitted and instruct the information transmission apparatus 100 to transmit information. If the CPU 131 accepts such an information transmission instruction in step S102 (YES in step S102), the CPU 131 reads sound source data from the sound source data storage unit 101 of the hard disk 134 (step S104). Note that there is no need to issue an information transmission request instruction from the user, and information transmission may be performed autonomously on the information transmission apparatus 100 side.

Next, the CPU 131 removes the mosquito band component from the sound source data (sound signal data) (step S105).
The CPU 131 reads out embedded information from the hard disk 134 (step S106), and encodes the embedded information into a digital signal according to a predetermined rule (step S107).

  Next, the CPU 131 determines whether or not to start packet transmission (step S108). That is, if packet transmission has not started yet, the CPU 131 determines that packet transmission has started (YES in step S108), and generates the above-described start packet (step S109).

  If packet transmission has already been performed in step S108, the CPU 131 determines that packet transmission has not started (NO in step S108), and the process proceeds to step S110. In step S110, the CPU 131 determines whether or not the packet transmission is finished (step S109). That is, when information to be transmitted as a packet still remains, the CPU 131 determines that the packet transmission is not finished (NO in step S110), and generates a data packet (step S114).

  If all the information to be transmitted as a packet has been transmitted in step S109, the CPU 131 determines that the packet transmission has ended (YES in step S110), and the CPU 131 generates the above-described end packet. (Step S115).

In order to generate each packet, the CPU 131 performs amplitude modulation on the carrier wave signal. At that time, based on the speaker characteristic information stored in the speaker characteristic storage unit 152 of the hard disk 134, the amplitude in which the speaker characteristic is compensated is set in each carrier wave signal.
Next, the CPU 131 performs phase adjustment on the carrier wave signal by adding the Schroeder phase to the carrier wave signal. Further, the CPU 131 performs inverse fast Fourier transform on the carrier wave signal.

  As described above, when any of the start packet, the data packet, and the end packet is generated, the CPU 131 generates the sound signal data from which the mosquito band component has been removed in step S105, the generated packet, and the step S101. The synthesized service area signal is synthesized (step S116), and the synthesized sound signal is output to the speaker 110 (step S117). As a result, a sound signal with a packet added to the mosquito band is output.

  When the transmission of one packet is completed, the CPU 131 determines whether or not the frame including the packet is completed (step S118). If the frame has not ended in step S118 (NO in step S118), CPU 131 returns the process to step S108, and generates the next packet. On the other hand, if the frame has ended (YES in step S118), CPU 131 determines whether or not all the frames have ended (step S119). If all the frames have not been completed in step S119 (NO in step S119), CPU 131 returns the process to step S106. On the other hand, if all frames have been completed (YES in step S119), CPU 131 ends the process.

[5. Operation of information receiving apparatus]
Next, the operation of the information receiving apparatus 200 will be described.

  FIG. 12 is a flowchart showing an operation procedure of information receiving apparatus 200 according to the present embodiment. The user of the information receiving apparatus 200 causes the processor 221 to execute the information receiving program 225, thereby causing the portable information terminal 200a to function as the information receiving apparatus 200.

  When the information reception program 225 is activated, the processor 221 first accumulates (buffers) the sound signal data received by the microphone 201 in the buffer 204 provided in the internal memory of the processor 221 (step S201). Next, the processor 221 performs fast Fourier transform on the accumulated sound signal data to convert the sound signal data into a frequency domain representation (step S202).

  The processor 221 substitutes the initial value “1” for the variable i (step S203), and detects the amplitude at the frequency of the i-th carrier signal among the plurality of carrier signals (step S204). Further, the CPU 221 compares the detected amplitude with a predetermined threshold value and determines whether or not a bit is set (step S205). At this time, the determination result when the bit is set is “1”, and the determination result when the bit is not set is “0”.

  The processor 221 determines whether or not the value of the variable i is 12 (the number of all carrier signals) (step S206). If the value of the variable i is not 12 (NO in step S206), the processor 221 The value is incremented by 1 (step S207), and the process returns to step S204. On the other hand, when the value of the variable i is 12 in step S206 (YES in step S206), the processor 221 stores the 12 bit determination result data obtained as described above in the storage device 222 ( Step S208).

  Next, the processor 221 determines whether or not the frame of received data has ended (step S209). If the frame has not ended (NO in step S209), the processor 221 returns the process to step S201, and if the frame has ended (YES in step S209), the processor 221 stores it in the storage device 222. The obtained bit determination result data is synthesized to restore information (step S210).

  When only the service area signal is output from the speaker 110, the service area signal is captured by the microphone. Also in this case, the processing of steps S201 to S210 is executed.

Next, the processor 221 determines whether or not a service area signal is included in the restored information (step S211). When the service area signal is included in the restored information (YES in step S211), processor 221 turns on the service area display (step S212). As a result, when the sound signal is output and the service area signal is superimposed on the sound signal, the sound signal is not output and only the service area signal is output from the speaker 110. Also, the service area display is turned on.
In other words, since the service area signal is transmitted regardless of the presence or absence of information other than the service area signal, the service area display may be turned on even when information other than the service area signal is not transmitted. Thus, the user can grasp that the user is present in the service area where information can be received.

  On the other hand, when the restored information does not include a service area signal (NO in step S211), processor 221 turns off the service area display (step S213). For example, when sound is output but the service area signal is not superimposed, sound other than the service area signal is output and the service area signal is superimposed, but the output level of the speaker 110 is low, or When the distance from the speaker 110 to the information receiving apparatus 200 is long and it is not determined that the bit is set in the bit determination of the service area signal, or when the signal other than the service area and the service area signal are not output In this case, the service area display is turned off.

  Here, the service area display will be described. A service area display area is provided on the display screen of the information receiving apparatus 200. In this service area display area, for example, two types of marks in which the shape of the antenna is designed can be displayed. When the restored information includes a service area signal, a mark indicating that the information receiving apparatus 200 is present in the service area (that is, the information receiving apparatus 200 is in a state in which embedded information can be received) Is displayed in the area. That is, a state where this mark is displayed is a state where the service area display is turned on. On the other hand, if the service area signal is not included in the restored information, it means that there is no information receiving apparatus 200 in the service area (that is, the information receiving apparatus 200 is not in a state where it can receive embedded information). A mark to be displayed is displayed in the area. That is, the state where this mark is displayed is the state where the service area display is turned off.

  Next, the processor 221 decodes the restored information (digital signal) according to a predetermined rule, and generates embedded information before the digital signal is encoded (step S214). Further, the processor 221 displays the decoded information on the display unit 210 (step S215). Thereby, the display unit 210 of the information receiving apparatus 200 displays information transmitted from the information transmitting apparatus 100 (the title of the music being played, the URL of the website related to the music being played, the artist name of the music being played) , The lyrics of the music being played, etc.) will be displayed. When the process of step S215 ends, the processor 221 returns the process to step S201.

  With the above configuration, information is put on the carrier wave signal by amplitude modulation, so that it is not easily affected by noise. Further, the sound in the mosquito band is not easily heard by humans, and deterioration of sound quality can be suppressed. Moreover, the speaker 110 should just be what can output the sound of the audible band widely marketed, and can suppress manufacturing cost.

  In the sound wave information communication system according to the present embodiment, the phase of the carrier wave signal is adjusted so as to reduce the difference between the maximum value and the minimum value of the amplitude of the carrier wave signal. When outputting sound, the power of the entire sound must be below a certain level, and when the carrier signal is output together with other sounds in the audible band other than the mosquito band, the maximum and minimum amplitudes of the carrier signal If the difference is large, it is necessary to suppress the amplitude of other sounds so that the power of the entire sound is not saturated at the maximum value. For this reason, by setting it as the said structure, the amplitude of said other sound can be enlarged. Further, in this embodiment, since the carrier signal phase is adjusted using the Schroeder phase, it is possible to minimize the difference between the maximum value and the minimum value of the amplitude in the waveform.

  In the sound wave information communication system according to the present embodiment, the frequency characteristics of the speaker 110 can be compensated, and even if the output level in the mosquito band is smaller than that in other frequency bands, the carrier signal Can be output at a high output level.

  Further, since the service area signal is transmitted separately from the carrier wave signal, when the service area signal is received by the information receiving apparatus 200, the information receiving apparatus 200 can receive the embedded information transmitted by the information transmitting apparatus. It can be judged that there is. For this reason, since it is possible to easily determine whether or not the embedded information can be received on the information receiving apparatus 200 side, convenience is improved.

[6. Other Embodiments]
In the embodiment described above, the configuration in which the embedded information is superimposed on the mosquito band of the sound such as music and transmitted as a sound wave has been described, but the present invention is not limited to this. Instead of superimposing the embedded information on the sound, only the embedded information may be transmitted as a sound wave on the carrier signal in the mosquito band. In this case, the listener feels silence, but the information receiving device can receive the embedded information.

  In the above-described embodiment, the packet including information of a total of 11 bits including the control signal 3 bits and the data signal 8 bits is generated and transmitted. However, the present invention is not limited to this. . For example, the packet may be generated with information of other number of bits such as 16 bits of the data signal. In addition, although one carrier wave signal represents 1-bit information, the present invention is not limited to this. A configuration may be adopted in which information of a plurality of bits is represented by adjusting the amplitude of one carrier signal in multiple stages.

  In the above-described embodiment, the configuration in which the phase adjustment is performed by giving the Schroeder phase to the carrier wave signal is described, but the present invention is not limited to this. For example, the phase of the carrier signal may be adjusted by another method, such as giving a random phase to the carrier signal.

  In the above-described embodiment, the information transmission apparatus 100 is realized by a computer. However, the present invention is not limited to this. For example, hardware capable of executing the same processing as the information transmission program 139 may be configured by an ASIC, FPGA, or the like, and an information transmission apparatus incorporating this may be configured. In addition, instead of configuring the information transmission apparatus 100 by one computer, the information transmission program 139 may be executed by distributed processing by a plurality of computers to form a distributed system including a plurality of computers.

  In the above-described embodiment, the information receiving apparatus 200 is realized by the portable information terminal. However, the present invention is not limited to this. For example, hardware capable of executing processing similar to that of the information reception program 225 may be configured by an ASIC, FPGA, or the like, and an information reception device incorporating the same may be configured.

DESCRIPTION OF SYMBOLS 1 Sound wave information communication system 100 Information transmitter 104 Encoder 105 Signal processing part 106 Service area signal generation part 107 Synthesis | combination part 110 Speaker (audible sound output part)
131 CPU
134 Hard disk 139 Information transmission program 151 Amplitude setting unit 152 Speaker characteristic storage unit 153 Phase adjustment unit 154 Inverse fast Fourier transform unit 200 Information reception device 201 Microphone (audible sound input unit)
205 Fast Fourier Transform Unit 206 Amplitude Detection Unit 207 Bit Determination Unit 208 Information Restoration Unit 209 Decoder 210 Display Unit 221 Processor 222 External Storage Device 225 Information Reception Program (Signal Analysis Unit)

Claims (13)

A signal processing unit that modulates amplitude based on information to be transmitted on a carrier signal in a specific band that is included in a human audible band but is difficult to listen;
An audible sound output unit capable of outputting sounds in the human audible band;
With
The audible sound output unit transmits the information by outputting a carrier wave signal amplitude-modulated by the signal processing unit as a sound of the specific band. A synthesis unit that synthesizes the carrier wave signal subjected to amplitude modulation to a sound signal to be heard by a human;
The information transmitting device according to claim 1, wherein the audible sound output unit outputs a signal obtained by synthesizing the carrier wave signal subjected to amplitude modulation to a sound signal to be heard by a human. A filter for attenuating signal components within the specific band in the sound signal to be heard by a human;
The information transmitting apparatus according to claim 2, wherein the synthesizing unit synthesizes the carrier wave signal subjected to amplitude modulation to the sound signal in which a signal component in the specific band is attenuated by the filter. The signal processing unit adjusts the phase of the carrier wave signal subjected to amplitude modulation so that a difference between the maximum value and the minimum value of the amplitude of the carrier wave signal subjected to amplitude modulation is reduced. The information transmission device according to any one of the above. The signal processing unit is configured to adjust the phase of the carrier signal x (t) according to the equations (1) to (3).
The information transmission device according to claim 4.

Here, N represents a positive integer, s (n) represents the amplitude of the carrier signal, θ (n) represents the phase of the carrier signal, and fc represents the fundamental frequency of the carrier signal. The signal processing unit is configured to perform amplitude modulation on a carrier wave signal while compensating for a difference in sound pressure level indicated by a sound pressure frequency characteristic of the audible sound output unit depending on the frequency. The information transmission device according to any one of the above. An identification signal generator for generating an identification signal for identifying whether or not the information is present in a range in which the information can be received;
The identification signal is a signal within the specific band,
The information transmission apparatus according to claim 1, wherein the identification signal generation unit generates the identification signal regardless of whether there is information to be transmitted other than the identification signal. The signal processing unit is configured to assign information to be transmitted to a plurality of frequencies of the specific band, and to modulate each of the carrier signals of each frequency based on the assigned information.
The information transmission device according to any one of claims 1 to 7. In a computer equipped with an audible sound output unit capable of outputting sounds in the human audible band,
Performing amplitude modulation on a carrier signal in a specific band, which is a frequency band included in the human audible band but difficult to hear, based on information to be transmitted;
Transmitting the information by causing the carrier wave signal amplitude-modulated by the signal processing unit to be output as the sound of the specific band from the audible sound output unit;
Information transmission program to execute. An audible sound input unit capable of inputting sounds in the human audible band;
From the sound received by the audible sound input unit, the amplitude of a frequency component in a specific band that is included in the human audible band but is difficult to hear is extracted, and information is restored based on the extracted amplitude. A signal analyzer to
Comprising
Information receiving device. Whether the signal analysis unit includes an identification signal for identifying whether the information receiving side is within a range where information can be received in the specific band of the sound received by the audible sound input unit Configured to determine whether or not
When it is determined by the signal analysis unit that the identification signal is included, receivable information indicating that the information exists in a receivable range is displayed, and the signal analysis unit identifies the reception availability When it is determined that no signal is included, the display unit further includes a display unit that does not display the receivable information.
The information receiving apparatus according to claim 10. In a computer equipped with an audible sound input unit capable of inputting sounds in the human audible band,
Extracting, from the sound received by the audible sound input unit, the amplitude of a frequency component of a specific band that is a frequency band that is included in a human audible band but difficult to hear;
Recovering information based on the extracted amplitude;
Information receiving program for executing Performing amplitude modulation on a carrier signal in a specific band, which is a frequency band included in the human audible band but difficult to hear, based on information to be transmitted;
Transmitting the information by outputting the amplitude-modulated carrier wave signal from an audible sound output unit capable of outputting sound in a human audible band; and
Receiving a sound in the human audible band;
Extracting the amplitude of the carrier signal that is a frequency component of the specific band from the received sound;
Recovering information based on the extracted amplitude;
Having
Information communication method.