JP2021196564A - Acoustic signal receiving method in acoustic receiving device, program and acoustic receiving device - Google Patents

Abstract

To provide an acoustic signal receiving method in an acoustic receiving device, a program and an acoustic receiving device which can suppress power consumption by optimizing whether or not to perform decoding process.SOLUTION: An acoustic receiving device 30 receives an acoustic signal AS in which embedded information SC is embedded by a microphone 31. The sound receiving device 30 includes: a volume detection unit 34 that detects volume of the acoustic signal Sas picked up by the microphone 31; a determination unit 35 that determines whether or not the detection volume detected by the volume detection unit 34 exceeds a threshold value; an extraction unit 36 that performs an extraction process for extracting the embedded information SC from the acoustic signal Sas; and a decoding unit 37 that performs a decoding process that decodes the embedded information SC into identification information ID. The decoding unit 37 performs decoding process when the detection volume exceeds the threshold value, and does not perform decoding process when the detection volume is equal to or less than the threshold value.SELECTED DRAWING: Figure 3

Description

The present invention relates to an acoustic signal receiving device, a program, and an acoustic signal receiving device for receiving information by embedding it in an acoustic signal such as a sound wave.

As an acoustic communication system, the technique described in Patent Document 1 is known. The acoustic communication system described in Patent Document 1 is an acoustic signal transmission device that emits an acoustic signal in which identification information is embedded by sound electron watermarking technology, and collects (receives) the emitted acoustic signal with a microphone. It is equipped with a sound receiving device (portable terminal). The acoustic receiving device extracts identification information from an acoustic signal and outputs the related information associated with the identification information to a display unit or a sound emitting unit to provide the user with the identification information. Embedded information in which identification information is encoded is embedded in an acoustic signal transmitted by an acoustic signal transmitter. Therefore, the acoustic receiving device includes a decoding unit that decodes the embedded information extracted from the received acoustic signal into identification information. The sound receiving device is used by being built in a mobile terminal such as a smartphone or a tablet, for example.

Japanese Unexamined Patent Publication No. 2016-153906

By the way, when the volume of the acoustic signal received by the acoustic receiver is low, a reception error occurs repeatedly. In this case, the decoding unit in the acoustic receiving device repeats the decoding process as long as the acoustic signal is received. In this way, the decoding unit repeats the decoding process without guaranteeing that the decoding process will succeed. Therefore, there is a problem that the power of the battery of the mobile terminal is wasted. Further, when the acoustic receiving device is configured to receive power from a commercial power source, there is a problem that power consumption increases.

Therefore, we provide an acoustic signal receiving method in an acoustic receiving device, a program, and an acoustic receiving device that can suppress power consumption by optimizing whether or not to perform decoding processing.

Hereinafter, means for solving the above problems and their actions and effects will be described.
(1) The sound receiving device that solves the above-mentioned problems is an sound receiving device that picks up an acoustic signal in which embedded information is embedded in a sound collecting unit, and collects the volume of the sound signal collected by the sound collecting unit. A volume detection unit for detection, a determination unit for determining whether or not the detection volume detected by the volume detection unit exceeds a threshold value, an extraction unit for extracting the embedded information from the acoustic signal, and the extraction unit. The decoding unit includes a decoding unit that decodes the embedded information into identification information, and the decoding unit performs the decoding process when the detection volume exceeds the threshold value, and the detection volume is equal to or lower than the threshold value. In that case, the decoding process is not performed.

According to this configuration, when the detection volume of the acoustic signal picked up by the sound picking unit is equal to or less than the threshold value, the decoding unit does not perform the decoding process. That is, when there is no acoustic signal or when the volume of the acoustic signal is excessively low and there is a high possibility that the decoding process will fail, the useless decoding process will not be performed. Therefore, the power consumption of the portable sound receiving device can be reduced. Therefore, the power consumption of the acoustic receiver can be suppressed by optimizing whether or not the decoding process is performed.

(2) In the acoustic receiving device, the volume detection unit may calculate the average volume of the acoustic signal per unit time, and the determination unit may make a determination by comparing the average volume with the threshold value. good.

According to this configuration, the determination unit makes a determination by comparing the average volume with the threshold value. For this reason, even if there is a momentary low volume part due to breathing of words in the voice contained in the acoustic signal or acoustic noise, there is a problem even if the acoustic signal is decoded by using the average volume per unit time. It is possible to appropriately determine whether or not the volume is appropriate.

(3) In the sound receiving device, the extraction unit may perform the extraction process when the detection volume exceeds the threshold value, and may not perform the extraction process when the detection volume is equal to or less than the threshold value. ..

According to this configuration, when the detection volume of the acoustic signal picked up by the sound picking unit is equal to or lower than the threshold value, the extraction processing is not performed in addition to the decoding processing. That is, when there is no acoustic signal or when the volume of the acoustic signal is excessively low and there is a high possibility that the decoding process will fail, the extraction process is not performed in addition to the decoding process. Therefore, the power consumption of the sound receiving device can be further reduced.

(4) In the acoustic receiving device, the determination unit further determines the presence / absence of the embedded information in the acoustic signal, and the decoding unit does not have the embedded information even if the detected volume exceeds the threshold value. If it is determined, the decoding process may not be performed.

According to this configuration, the determination unit determines whether or not there is embedded information in the acoustic signal. If there is no embedded information, the decoding process is not performed even if the detection volume exceeds the threshold value. That is, when the embedded information is not embedded in the acoustic signal, useless decoding processing is not performed. Therefore, the power consumption of the sound receiving device can be reduced. Therefore, the power consumption of the acoustic receiver can be suppressed by optimizing whether or not the decoding process is performed.

(5) In the sound receiving device, the determination unit may determine the presence or absence of the embedded information based on the extraction processing result by the extraction unit or the decoding processing result by the decoding unit.

According to this configuration, the presence / absence of the embedded information is determined by using the extraction processing result by the extraction unit or the decoding processing result by the decoding unit, so that it is not necessary to separately provide a processing unit for detecting the presence / absence of the embedded information. Moreover, the presence or absence of embedded information can be accurately determined. Therefore, there are fewer problems that the decoding process is not performed even though there is embedded information, and conversely, the decoding process is performed even though there is no embedded information. Therefore, the power consumption of the sound receiving device can be appropriately reduced.

(6) In the sound receiving device, if it is determined that there is no embedded information even if the detection volume exceeds the threshold value, the extraction unit may stand by without performing the extraction process.
According to this configuration, when it is determined that there is no embedded information even if the detection volume exceeds the threshold value, the decoding unit waits without performing the decoding process, and the extraction unit waits without performing the extraction process. Therefore, the power consumption of the sound receiving device can be further reduced.

(7) In the sound receiving device, when the detected volume exceeds the threshold value, the output unit is made to output the provided information corresponding to the identification information obtained by the decoding by the decoding unit, and the detected volume is equal to or lower than the threshold value. If this is the case, the output unit may be provided with a control unit that outputs the fact that there is no provided information.

According to this configuration, when the detection volume exceeds the threshold value, the provided information corresponding to the identification information obtained by the decoding by the decoding unit is output to the output unit. On the other hand, when the detection volume is equal to or less than the threshold value, the decoding unit does not perform decoding, and the output unit outputs that there is no provided information. In addition to being able to appropriately provide useful information to users, it is possible to reduce errors in which inappropriate information is provided due to decoding failure. Therefore, the power consumption of the sound receiving device can be appropriately reduced, and useful information can be appropriately provided to the user.

(8) In the acoustic receiving device, the embedded information in which the same identification information is encoded is embedded in the acoustic signal a plurality of times in succession, and each time the decoding unit succeeds in decoding, the embedded information is embedded. May wait without decoding during the first waiting time corresponding to the plurality of times in succession.

According to this configuration, even if the sound collecting unit receives the acoustic signal, at least decoding is not performed during the predetermined standby time, so that the power consumption of the battery can be further reduced. In this case, when the volume exceeds the threshold value, if the embedded information is successfully decoded for the first time out of a plurality of consecutive times, the embedded information is the same identification information for the remaining number of repetitions. Since the decoding is performed in the meantime, the number of unnecessary decodings can be reduced by waiting without performing the decoding during that time. The predetermined waiting time corresponding to a plurality of times is not limited to the waiting time corresponding to a plurality of times, but may be a waiting time corresponding to one or two times less than the plurality of times.

(9) In the sound receiving device, when the number of consecutive times when the detection volume is determined by the determination unit to be equal to or less than the threshold value reaches the set number of times, the volume detection unit performs the detection volume during the second standby time. You may wait without detecting.

According to this configuration, when the number of consecutive times when the detection volume is determined to be equal to or less than the threshold value reaches the set number of times, the detection volume is not detected during the second standby time. When the embedded information cannot be correctly decoded due to the noise around the user carrying the mobile terminal, not only the decoding is not performed, but also the unnecessary detection volume is not detected and determined. Therefore, the power consumption of the battery of the mobile terminal can be further reduced.

(10) The acoustic receiving device is provided in a mobile terminal having a battery, and includes a control unit for detecting the remaining amount of the battery, and the control unit is more than when the remaining amount of the battery is the first remaining amount. The second standby time may be set to a longer time when the remaining amount is smaller than that of the first remaining amount.

According to this configuration, the lower the remaining battery level of the mobile terminal, the longer the second standby time is set, and the power consumption of the battery can be reduced.
(11) The program for solving the above-mentioned problems is a program for causing a computer included in an acoustic receiving device for collecting an acoustic signal in which embedded information is embedded to be picked up by a sound collecting unit, and the program is a program for collecting the computer. A volume detection unit that detects the volume of the acoustic signal picked up by the sound unit, a determination unit that determines whether or not the detection volume detected by the volume detection unit exceeds a threshold value, and an embedded information is extracted from the acoustic signal. When the detection volume exceeds the threshold value, the extraction process is performed to decode the embedded information into identification information, and when the detection volume is equal to or less than the threshold value, the decoding process is performed. It functions as a decoding unit that does not perform. Therefore, by letting the computer execute the program, the power consumption of the sound receiving device can be suppressed by optimizing whether or not the decoding process is performed.

(12) The acoustic signal receiving method in the acoustic receiving device that solves the above-mentioned problems is the acoustic signal receiving method in the acoustic receiving device that picks up the acoustic signal in which the embedded information is embedded in the sound collecting unit, and is the sound collecting method. A volume detection step for detecting the volume of the acoustic signal collected by the unit, a determination step for determining whether or not the detected volume detected in the volume detection step exceeds a threshold value, and the embedded information from the acoustic signal. An extraction step for performing extraction processing for extraction and a decoding process for decoding the embedded information into identification information when the detection volume exceeds the threshold value are performed, and when the detection volume is equal to or lower than the threshold value, the decoding process is performed. It includes a decoding step that does not perform processing. Therefore, the power consumption of the acoustic receiving device can be suppressed by optimizing whether or not the decoding process is performed.

According to the present invention, the power consumption of the acoustic receiving device can be suppressed by optimizing whether or not to decode the embedded information.

The schematic diagram which shows the acoustic communication system in 1st Embodiment. The schematic diagram which shows the acoustic communication system. The block diagram which shows the structure of an acoustic communication system. A graph illustrating the echo diffusion method. A flowchart showing an acoustic signal reception process. The block diagram which shows the structure of the acoustic receiving apparatus in 2nd Embodiment. A flowchart showing an acoustic signal reception process.

(First Embodiment)
Hereinafter, the acoustic communication system 10 of the first embodiment will be described with reference to FIGS. 1 to 5.
As shown in FIG. 1, the acoustic communication system 10 has an acoustic transmission device 20 having a speaker 12 as an example of one or a plurality of sound emitting units, and a portable device that receives an acoustic signal AS emitted from the speaker 12. A sound receiving device 30 built in the terminal 15 is provided. Embedded information SC (see FIG. 2) is embedded in the acoustic signal AS. The user carries a portable mobile terminal 15 and moves around. The acoustic receiving device 30 built in the mobile terminal 15 receives the embedded information SC embedded in the acoustic signal AS. For example, the user receives the acoustic signal AS broadcast from the speaker 12 of the broadcasting main body such as a station, a shopping district, or a public facility by the acoustic receiving device 30 of the mobile terminal 15. The mobile terminal 15 is, for example, a mobile phone, a smartphone, a tablet, a notebook computer, or the like. The sound receiving device 30 acquires the provided information provided by the broadcasting subject based on the embedded information SC embedded in the sound signal AS. In this way, the user who uses the sound receiving device 30 can receive the provided information provided by the broadcasting subject.

The broadcasting subject is, for example, a person or a business operator who broadcasts the acoustic signal AS, or a person or a business operator who requests the broadcasting of the acoustic signal AS. The broadcasting subject may be a person or a business operator who forms the acoustic signal AS by himself / herself. The broadcaster does not have to be a person or a business operator who forms the acoustic signal AS by himself / herself. For example, broadcasters are businesses that operate stores, businesses that operate public transportation such as railways, businesses or groups of learning facilities including schools, businesses that operate museums and exhibitions, pools, etc. Businesses that operate leisure facilities, businesses that operate accommodation facilities, local governments that broadcast disaster warnings, etc.

The provided information is information provided by the broadcaster to the user. The storage location of the provided information is not limited. In one example, the provided information is stored in a server on the Internet IN. In another example, the provided information is stored in the acoustic receiver 30. The following is an example of the information provided. In the case of a business operator whose broadcasting entity operates a store, the provided information is the detailed contents of the products in the store. If the broadcaster is a municipality, the information provided is a map showing where to evacuate in the event of a disaster. If the broadcaster is the operator of the exhibition, the information provided is information that indicates the details of the exhibit. The provided information may be an announcement obtained by translating an announcement broadcast as an acoustic signal AS into another language. When the broadcasting subject is a movie theater, the provided information may be subtitles of the dialogue of the movie. The provided information may be link information (for example, URL: Uniform Resource Locator) indicating a place where detailed information is stored. In this embodiment, the provided information is provided as a URL on the Internet IN. The provided information may be displayed on the display unit 17 of the mobile terminal 15, may be emitted from the headphones or earphones connected to the earphone jack of the mobile terminal 15, or may be emitted from the speaker of the mobile terminal 15. You may.

The acoustic signal AS is a sound wave including frequencies in the audible range. The embedded information SC is embedded in the acoustic signal AS by a digital watermark. The acoustic signal AS is broadcast from the broadcasting device 11. Examples of acoustic signals AS include announcements, alarms, general or visually impaired sound signs, BGM (background music), explanatory audio output at museums and exhibitions, and program broadcasts. The data length of one embedded information SC embedded by a digital watermark is, for example, about 8 bits. Further, in the acoustic signal AS, acoustic noise is added to the acoustic signal AS due to various causes such as the propagated distance, the volume of sound emitted, the presence or absence of obstacles, and the noise around the user carrying the mobile terminal 15. Or the volume of the acoustic signal AS becomes excessively low. In this case, there is a high possibility that the mobile terminal 15 cannot receive the embedded information SC embedded in the acoustic signal AS. Therefore, the sound transmitting device 20 repeatedly emits the same embedded information SC a plurality of times so that even if the sound receiving device 30 fails to receive the embedded information SC once, it can be received next time.

As shown in FIG. 2, the acoustic transmission device 20 includes a device main body 20A and a speaker 12 connected to the device main body 20A. The acoustic transmission device 20 generates an acoustic signal Sas, which is a digital signal, by embedding the embedded information SC in the original sound signal OS (see FIG. 3), and emits an acoustic signal AS based on the acoustic signal Sas from the speaker 12. .. The acoustic signal AS is composed of an original sound signal OS composed of voice or music, and a plurality of embedded information SCs embedded one by one for one original sound in the original sound signal OS.

The mobile terminal 15 has a built-in sound receiving device 30. The sound receiving device 30 is composed of an application (software) installed in the mobile terminal 15 and a CPU (not shown) that executes the application. The mobile terminal 15 includes a microphone 31 as an example of a sound collecting unit. The mobile terminal 15 collects the acoustic signal AS by the microphone 31. Further, the acoustic receiving device 30 takes in the acoustic signal AS picked up by the microphone 31 as an electric signal, and extracts the embedded information SC from the acoustic signal Sas composed of the electric signal. The sound receiving device 30 restores the embedded information SC to the identification information ID. The sound receiving device 30 outputs the provided information corresponding to the identification information ID to the mobile terminal 15. As a result, the user can see the provided information displayed on the display unit 17 (see FIG. 3) of the mobile terminal 15, or the headphones, earphones, or speakers connected to the earphone jack of the mobile terminal 15 (all not shown). ) Can listen to the provided information output.

Next, the configuration of the sound transmitting device 20 and the sound receiving device 30 will be described with reference to FIG. In this embodiment, the sound wave is referred to as an acoustic signal AS and the electrical signal is referred to as an acoustic signal Sas in order to distinguish between a sound signal generated by a sound wave transmitted in space and an electric signal. Further, the original sound signal OS is an electric signal. Further, in the embedded information SC, what is embedded in the acoustic signal AS is a sound wave, and what is embedded in the acoustic signal Sas is an electric signal.

The sound transmission device 20 embeds the identification information ID in the original sound signal OS by the sound digital watermarking technique, and emits the sound from the speaker 12 as the sound signal AS. The identification information ID is embedded in the acoustic signal AS as the embedded information SC. The acoustic transmission device 20 may be built in a broadcasting device 11 including a speaker 12 that outputs an acoustic signal AS as a sound wave. On the other hand, the sound receiving device 30 is built in a mobile terminal 15 such as a smartphone. The sound receiving device 30 extracts the embedded information SC from the sound signal Sas picked up by the microphone 31. The sound receiving device 30 is configured as a device built in the mobile terminal 15, but may be the mobile terminal 15 itself.

First, a detailed configuration of the acoustic transmission device 20 will be described with reference to FIG.
The sound transmission device 20 includes a first input unit 21 for inputting the original sound signal OS and a second input unit 22 for inputting the identification information ID. The sound transmission device 20 includes a first control unit 23 that collectively controls the sound transmission device 20. Further, the acoustic transmission device 20 includes a diffusion code generator 26, an encoding unit 27, an embedded unit 28 having a function of convolving the embedded information SC in the original sound signal OS, and a transmission unit 29 including an amplifier and the like.

Further, the diffusion code generator 26 generates a diffusion code. The diffusion code may be any code. For example, the PN sequence is used as the diffusion code. The PN sequence is a sequence called Pseudo-Noise Sequence: pseudo-noise sequence.

The encoding unit 27 encodes (encodes) the identification information ID into the embedded information SC. The embedded information SC in which the identification information ID is encoded is, for example, 8-bit information.
The embedding unit 28 embeds the embedding information SC in the acoustic signal AS by convolving the embedding information SC in the original sound signal OS. The original sound signal OS is, for example, an audio signal such as an announcement or a music signal such as BGM. The original sound signal OS of this example functions as a transmission medium (carrier wave) in which the embedded information SC is embedded. Further, the original sound signal OS of this example has a frequency in the audible range. The original sound signal OS may have a frequency in the non-audible range.

The method in which the embedding unit 28 convolves the embedding information SC in the original sound signal OS and embeds it is an echo diffusion method or a spread spectrum method. The embedding method may be another method. It is preferable to adopt a diffusion method in which the diffusion code of the PN sequence functions as a secret key in terms of enhancing the confidentiality of the embedded information SC.

The sound transmission device 20 includes an electronic board on which a CPU, a memory, and the like are mounted. A program for acoustic signal generation processing is stored in the memory. By executing the program read from the memory by the CPU, each part 23, 26 to 28 made of software is configured in the sound transmission device 20. That is, the program stored in the memory in the sound transmission device 20 causes the computer to function as each unit 23, 26 to 28. Each unit 23, 26 to 28 may be configured by software and hardware, or may be configured by hardware.

Next, with reference to FIG. 3, a mobile terminal 15 having a built-in sound receiving device 30 will be described.
The mobile terminal 15 has a microphone 31 that functions as an example of a sound collecting unit that collects an acoustic signal AS, an operation unit 16 that is operated by a user, and a display unit 17 that is an example of an output unit that outputs provided information and the like. And a battery BT, and various functional units that function as a mobile terminal. The various functional units include a telephone function unit, a mail function unit, an Internet communication function unit, a GPS function unit, and the like.

The sound receiving device 30 includes a second control unit 32 that collectively controls the sound receiving device 30. Further, the acoustic receiving device 30 includes a receiving unit 33 including an amplifier and the like, which converts the acoustic signal AS picked up by the microphone 31 into the acoustic signal Sas which is an electric signal.

The acoustic receiving device 30 includes a volume detecting unit 34 that detects the volume of the acoustic signal Sas output from the receiving unit 33, and a determining unit 35 that determines whether or not the detected volume detected by the volume detecting unit 34 exceeds the threshold value. To prepare for. Further, the acoustic receiving device 30 uses the extraction unit 36 that extracts the embedded information SC from the acoustic signal Sas input from the receiving unit 33 and the embedded information SC extracted from the acoustic signal Sas by the extraction unit 36 as the identification information ID. A decoding unit 37 for decoding is provided. Further, the sound receiving device 30 includes a memory 38 that stores necessary data including a reference table DT and set values, and a display processing unit 39 that performs processing for displaying provided information and the like on the display unit 17. The set value includes a threshold value for determination, a set number of times to be described later, a first waiting time T1 and a second waiting time T2.

The acoustic signal Sas output from the receiving unit 33 is input to the volume detection unit 34 and the extraction unit 36. The volume detection unit 34 detects the volume of the acoustic signal AS picked up by the microphone 31. Specifically, the volume detection unit 34 calculates the average level of the volume of the acoustic signal Sas per unit time based on the acoustic signal Sas input from the receiving unit 33, so that the average of the acoustic signals AS picked up by the microphone 31 is obtained. Detect the volume. The determination unit 35 determines whether or not the average volume, which is an example of the detection volume detected by the volume detection unit 34, exceeds the threshold value. Here, the threshold value is set to the upper limit of the volume of the predetermined value or less, which is considered that the embedded information SC cannot be correctly decoded into the identification information ID. In this example, by determining the average volume of the acoustic signal Sas, whether or not the volume of the embedded information SC embedded at a constant ratio to the volume of the original sound in the acoustic signal Sas can be correctly decoded. Is indirectly determined.

Here, the threshold value can be set to an appropriate value from the viewpoint of power saving and utilization of the provided information. For example, the threshold value may be set to a value that allows selection not to decode when the probability of not being correctly decoded becomes 100%. Further, the threshold value may be set to a value that allows selection not to decode when the probability of not being correctly decoded is 50% or more.

When the average volume of the acoustic signal Sas exceeds the threshold value, the determination unit 35 activates the extraction unit 36 and the decoding unit 37. On the other hand, the determination unit 35 does not activate the extraction unit 36 and the decoding unit 37 when the average volume of the acoustic signal Sas does not exceed the threshold value. Specifically, when the average volume exceeds the threshold value, the determination unit 35 outputs the determination value “1” to the extraction unit 36 and the decoding unit 37. On the other hand, if the average volume does not exceed the threshold value, the determination unit 35 outputs the determination value “0” to the extraction unit 36 and the decoding unit 37.

The extraction unit 36 is activated when the determination value "1" is input, and is not activated or is stopped when the determination value "0" is input. Further, the decoding unit 37 is activated when the determination value "1" is input, and is not activated or is stopped when the determination value "0" is input. In this way, when the extraction unit 36 is activated, the decoding unit 37 is also activated, while when the extraction unit 36 is not activated, the decoding unit 37 is not activated either. Therefore, although the volume detection unit 34 and the determination unit 35 are activated while the sound receiving device 30 is being activated, the extraction unit 36 and the decoding unit 37 are being received while the acoustic signal Sas whose average volume is equal to or less than the threshold value is being received. Does not start. Then, during the activation of the acoustic receiving device 30, the extraction unit 36 and the decoding unit 37 are activated only when the acoustic signal Sas whose average volume exceeds the threshold value is received.

The extraction unit 36 extracts the embedded information SC from the acoustic signal Sas by a method according to the diffusion method adopted by the acoustic communication system 10 as the method of embedding the embedded information SC. When the embedding method is the echo diffusion method, the extraction unit 36 extracts the embedding information SC diffused on the time axis as an echo of the original sound included in the original sound signal OS from the acoustic signal Sas. Specifically, the extraction unit 36 extracts the embedded information SC consisting of a sequence of binary values "0" and "1" determined by the time interval of a plurality of peaks to be extracted by performing cepstrum conversion on the acoustic signal Sas. .. When the embedding method is a spread spectrum method, the extraction unit 36 extracts the embedding information SC from the acoustic signal Sas by demodulating the embedding information SC spectrum-spread to the original sound included in the original sound signal OS. do. When the embedding method is another method, the extraction unit 36 extracts the embedding information SC from the acoustic signal Sas by an extraction method according to the other method. The details of the echo diffusion method will be described later.

The decoding unit 37 decodes the embedded information SC into the identification information ID. The decoding unit 37 decodes the embedded information SC into the identification information ID by performing despreading with respect to the diffusion using the diffusion code adopted by the encoding unit 27 of the acoustic transmission device 20. Specifically, the decoding unit 37 uses a diffusion code to cross-correlate the PN sequence diffused by the embedding unit 28 with the same PN sequence, thereby converting the embedded information SC into an identification information ID before encoding. Decrypt. The decoding unit 37 sends the decoded identification information ID to the second control unit 32.

The sound receiving device 30 includes an electronic board on which a CPU, a memory 38, and the like are mounted. A program for acoustic signal reception processing (see FIG. 5) is stored in the memory 38. By executing the program read from the memory 38, the CPU functions as each unit 32 to 37, 39 composed of software in the sound receiving device 30. That is, the program stored in the memory 38 in the sound receiving device 30 causes the computer to function as each unit 32 to 37, 39. Specifically, the program stored in the memory 38 in the sound receiving device 30 functions the computer as a second control unit 32, a volume detection unit 34, a determination unit 35, an extraction unit 36, a decoding unit 37, and a display processing unit 39. Let me. Of the units 32 to 37, 39, one or both of the receiving unit 33 and the display processing unit 39 may be the hardware included in the mobile terminal 15. Further, each part 32, 34 to 37 may be configured by software and hardware, or may be configured by hardware.

Next, with reference to FIG. 4, the embedding method for embedding the embedding information SC in the acoustic signal Sas will be described by taking the echo diffusion method as an example. FIG. 4 shows the original sound by the echo diffusion method and the echo kernel. The time axis is divided into multiple time frames from the offset time when the original sound has an offset time for "1", and the PN sequence is used for multiple time frames to correspond to each of the two values "0" and "1". Multiple peaks are located at different time points. α is the embedding strength when the diffusion length L is used. That is, α is the amplitude of the PN sequence that forms the echo. In the echo diffusion method, the same detection accuracy is ensured even if the embedding strength α is set to 1 / L with respect to the embedding strength of the single echo in the echo method. The digital watermark embedding process is performed by the embedding unit 28 convolving the original signal and the echo kernel. At the time of detection, the extraction unit 36 performs cepstrum conversion on the signal of the embedded information SC embedded in the original signal. On the other hand, when the spread spectrum method is adopted, the embedded unit 28 spreads the PN sequence in an occupied band several tens of times as large as that of the carrier wave before modulation. At the time of detection, the extraction unit 36 performs backdiffusion to extract the embedded information SC. Here, the unit intensity "1" of the original sound corresponds to the volume of the original sound in the acoustic signal Sas, and the embedding intensity α corresponds to the volume of the signal component of the embedded information SC. Then, the embedded information SC is embedded in the original sound signal OS at a volume of a constant ratio α with respect to the volume of the original sound.

Next, the operation of the acoustic communication system 10 will be described.
A user carrying a mobile terminal 15 moves around a station or a shopping district, watches in a museum, a movie theater, or watches or watches a game in a facility such as a stadium or a conference hall. The user operates the operation unit 16 under the power-on state of the mobile terminal 15 to activate the sound receiving device 30. An acoustic signal AS is emitted from the speaker 12 of the broadcasting device 11 mainly for broadcasting in the area where the user moves or in the facility for viewing. The mobile terminal 15 collects the acoustic signal AS with the microphone 31. The acoustic receiving device 30 provides the provided information to the user by outputting the provided information corresponding to the embedded information SC embedded in the received acoustic signal AS to the mobile terminal 15.

When the sound receiving device 30 is activated while the power of the mobile terminal 15 is turned on, the CPU of the mobile terminal 15 executes the program of the sound signal reception processing routine shown in FIG. When the acoustic signal AS is emitted from the speaker 12 of the acoustic transmitter 20, the microphone 31 of the portable terminal 15 while the power is on picks up the acoustic signal AS. The receiving unit 33 amplifies the acoustic signal Sas from the microphone 31 and outputs it to the volume detection unit 34 and the extraction unit 36. The extraction unit 36 and the decoding unit 37 do not start while the determination value input from the determination unit 35 is "0" even during the activation of the sound receiving device 30. The extraction unit 36 that has not been activated does not accept the acoustic signal Sas.

Hereinafter, the operation of the sound receiving device 30 driven by the CPU of the mobile terminal 15 by executing the program will be described with reference to FIG. The program corresponds to an application that is installed in a mobile terminal 15 and causes a CPU (computer) to function as each unit 32 to 39 constituting the sound receiving device 30. The CPU executes the program every predetermined unit time (for example, a time in the range of several milliseconds to several tens of milliseconds).

First, in step S11, the CPU determines whether or not the acoustic signal Sas has been received. That is, the CPU determines whether or not the receiving unit 33 has input the acoustic signal Sas. If the acoustic signal Sas is not received, the process waits as it is, and if the acoustic signal Sas is received, the process proceeds to step S12.

In the next step S12, the CPU determines whether or not the waiting time has elapsed. Here, the waiting time includes the first waiting time T1 set when the determination result in step S14 is affirmative in the processing before the previous time, and the determination result in step S14 in the processing before the previous time is a negative determination. The second standby time T2 set when the number of consecutive times reaches the set number of times is included. The first standby time T1 is set to a time corresponding to a plurality of times in which the embedded information SC in which the same identification information ID is encoded is repeatedly embedded in the acoustic signal AS. The first standby time T1 is set to, for example, a time within the range of 0.1 to 2 seconds. Further, the second standby time T2 is set when the number of consecutive times when the detection volume becomes equal to or less than the threshold value reaches the set number of times, and then, for a while, the acoustic signal AS becomes a volume at which the detection volume exceeds the threshold value. Set when there is no hope of returning. For example, when the position of the mobile terminal 15 carried by the user is far from the speaker 12 of the broadcasting device 11, the number of consecutive times when the detection volume becomes equal to or less than the threshold value may reach the set number of times. On the other hand, if there is a temporary obstacle between the speaker 12 and the mobile terminal 15, or if temporary acoustic noise rides on the acoustic signal AS, the number of times the detection volume falls below the threshold value is one. The number of consecutive times may not reach the set number, such as when it ends. In this case, the second standby time T2 is not set. Therefore, the affirmative determination is made in step S12 again next time. If the waiting time has elapsed, the CPU proceeds to step S13, and if the waiting time has not elapsed, the CPU ends the routine. During the waiting period waiting for the elapse of the waiting time, the power consumption of the CPU that executes the calculation of the average volume (step S13) and the determination process (step S14) is saved.

In step S13, the CPU calculates the average volume. This process is performed by the volume detection unit 34. The volume detection unit 34 calculates the average volume of the acoustic signal Sas by sampling the volume of the N points per unit time of the acoustic signal Sas, integrating the volumes of the N points, and dividing the total value by N. The average volume of the acoustic signal Sas per unit time corresponds to an example of the detected volume. In this embodiment, the process of step S13 corresponds to an example of the volume detection step.

In the next step S14, the CPU determines whether or not the average volume exceeds the threshold value. This determination is performed by the determination unit 35. If the average volume exceeds the threshold value, the process proceeds to step S15, and if the average volume does not exceed the threshold value, the process proceeds to step S18. Here, if the average volume exceeds the threshold value, the determination unit 35 outputs the determination value “1”, so that the extraction unit 36 and the decoding unit 37 are activated. On the other hand, if the average volume does not exceed the threshold value, the determination unit 35 outputs the determination value "0", so that the extraction unit 36 and the decoding unit 37 are not started or are stopped. In this embodiment, the process of step S14 corresponds to an example of the determination step.

In step S15, the CPU extracts the embedded information SC. This process is performed by the extraction unit 36. The extraction unit 36 extracts the embedded information SC from the acoustic signal Sas input from the reception unit 33. The extraction of the embedded information SC is performed by an extraction method according to the diffusion method adopted such as an echo diffusion method or a spread spectrum method. In this embodiment, the process of step S15 corresponds to an example of the extraction step.

In the next step S16, the CPU executes the decoding process. This process is performed by the decoding unit 37. The decoding unit 37 decodes the embedded information SC into the identification information ID before encoding by taking a cross-correlation with the same PN sequence as the PN sequence diffused by the embedded information SC with respect to the embedded information SC. do. The decoding unit 37 sends the decoded identification information ID to the second control unit 32.

In the next step S17, the CPU causes the output unit to output the provided information corresponding to the identification information ID. This process is performed by the second control unit 32. The second control unit 32 acquires the provided information corresponding to the identification information ID by referring to the reference table DT (see FIG. 3) stored in the memory 38 based on the identification information ID. Then, the second control unit 32 displays or outputs the provided information by voice. That is, the second control unit 32 displays the provided information on the display unit 17 via the display processing unit 39, or the headphone or earphone connected to the earphone jack by the sound emission processing unit, or the speaker of the mobile terminal 15 (either Also, the provided information is emitted from (not shown).

For example, on the display unit 17 of the mobile terminal 15, any one of store information, product information, coupon information, a map, an explanation of an exhibit, a translation of an announcement, etc. related to an announcement of the original sound signal OS may be displayed. Multiple are displayed. Further, from the headphones, earphones or speakers connected to the mobile terminal 15, any one of store information, product information, coupon information, route guidance voice, translation voice of the announcement, etc. related to the announcement of the original sound signal OS or the like. Multiple sounds are emitted. For example, when the original sound signal OS is music such as BMG, when the user carrying the mobile terminal 15 is moving in a shopping district or a department store, among the store information, product information, coupon information, map, and route guidance voice. One or more are displayed or emitted on the mobile terminal 15. Further, when the original sound signal OS is music such as BMG, the explanation when the user carrying the mobile terminal 15 is in a museum, a museum, a station, or a facility such as a stadium or a conference hall. One or a plurality of sentences, explanation voices corresponding to multiple languages, guidance sentences, guidance voices corresponding to multiple languages, and the like are displayed or emitted on the mobile terminal 15.

On the other hand, if the average volume does not exceed the threshold value, the CPU sets the standby time in step S18. Here, the CPU sets the second standby time T2. That is, even when the volume of the acoustic signal Sas exceeds the threshold value, if it is determined that the embedded information SC is not embedded in the acoustic signal Sas, the determination unit 35 outputs the determination value "0". , The activation of the extraction unit 36 and the decoding unit 37 is stopped, or the stopped state is continued. Then, the waiting time for continuing the stopped state is set. Then, in the next step S19, the CPU causes the output unit to output that there is no provided information. This process is performed by the second control unit 32. The second control unit 32 displays or outputs by voice that there is no provided information. That is, the second control unit 32 causes the display unit 17 to display the fact that there is no provided information via the display processing unit 39, or the headphone or earphone connected to the earphone jack by the sound emission processing unit, or the mobile terminal 15. Sounds to the effect that there is no provided information may be emitted from speakers (all not shown). Here, the fact that there is no provided information may be information such as "cannot be received", "cannot be detected", or "out of reception area", in addition to the output of "no provided information". .. In this embodiment, the processes of steps S17 and S19 correspond to an example of the output step.

Further, in the present embodiment, the embedded information SC in which the same identification information ID is encoded is continuously embedded in the acoustic signal AS emitted from the speaker 12 of the acoustic transmission device 20 a plurality of times. That is, the microphone 31 of the sound receiving device 30 continuously receives the embedded information SC in which the same identification information ID is encoded a plurality of times. When the average volume, which is the detection volume, exceeds the threshold value (affirmative determination in step S14), the second control unit 32 responds to a plurality of consecutive times of the embedded information SC each time the decoding unit 37 succeeds in decoding. 1 Set the standby time T1. In this case, if the embedded information SC succeeds in decoding the first embedded information SC out of a plurality of consecutive times, then the embedded information SC has the same identification information during the remaining number of repetitions of the embedded information SC. Since it is decoded into an ID, the number of unnecessary decodings can be reduced by waiting without decoding during that time.

Here, the first waiting time T1 corresponding to a plurality of times is not limited to the waiting time corresponding to the remaining number of repetitions ((multiple times-1) times) among the plurality of times, and is once more than the number of repetitions or. The waiting time corresponding to two less times may be used. For example, assuming that the number of times the embedded information SC having the same identification information ID is continuous is n times and the interval time of the embedded information SC is t seconds, the first embedded information SC is embedded nth time from the time of reception. For example, (n-1) t seconds, which is the time corresponding to (n-1) times remaining until the reception timing for receiving the information SC, is defined as the first standby time T1. The first standby time T1 may be set to an appropriate value within the range of (n−k) t ≦ T1 <nt. However, k is a natural number satisfying n−k ≧ 1. In this way, each time the decoding unit 37 succeeds in decoding, the embedded information SC waits without decoding during the first waiting time T1 corresponding to a plurality of consecutive times.

Further, when the average volume which is the detection volume is equal to or less than the threshold value (negative determination in step S14), the CPU counts the number of consecutive times when the detection volume does not exceed the threshold value by a counter (not shown). Then, when the number of consecutive times reaches the set number of times, the CPU sets the second standby time T2. The second waiting time T2 is set to a longer time than the first waiting time T1 (T2> T1).

Further, the second control unit 32 may detect the remaining amount of the battery BT and adjust the length of the second standby time T2 according to the remaining amount of the battery BT. For example, the second control unit 32 sets the second standby time T2 when the remaining amount of the battery BT is the second remaining amount, which is smaller than the first remaining amount, than when the remaining amount of the battery BT is the first remaining amount. Set to a longer time. In this case, the second standby time T2 may be set in a plurality of stages so as to change stepwise with respect to the remaining battery level, or may be set so as to continuously change with respect to the change in the remaining battery level. You may.

Further, the second control unit 32 may change the number of continuous times according to the remaining amount of the battery BT. For example, the second control unit 32 reduces the number of consecutive times when the remaining amount of the battery BT is the second remaining amount, which is less than the first remaining amount, than when the remaining amount of the battery BT is the first remaining amount. Set to. Therefore, as the remaining amount of the battery BT is smaller, the standby of the second standby time T2 is started earlier with a smaller number of consecutive times when the detection volume becomes equal to or less than the threshold value.

Then, according to the portable terminal 15 incorporating the acoustic receiving device 30 of the present embodiment, when the volume of the received acoustic signal Sa exceeds the threshold value and the embedded information SC can be correctly decoded into the identification information ID, the detection volume is high. As long as the extraction unit 36 and the decoding unit 37 are activated. On the other hand, when the volume of the received acoustic signal Sas is equal to or lower than the threshold value and the detection volume is such that there is a high possibility that the embedded information SC cannot be correctly decoded into the identification information ID, the extraction unit 36 and the decoding unit 37 are not activated. Therefore, the wasteful consumption of the battery power of the mobile terminal 15 can be reduced.

Therefore, even if the user carries the mobile terminal 15 with the sound receiving device 30 activated, the user does not have to worry about the power consumption of the battery BT so much. As a result, useful information can be obtained from the mobile terminal 15 in a shopping district, a facility, or the like while the sound receiving device 30 is activated. Further, even though the volume of the acoustic signal Sas is too low, an error output in which erroneous provision information corresponding to the erroneous identification information ID is output from the mobile terminal 15 due to forcibly decoding the embedded information SC. The frequency of occurrence of

As described in detail above, according to the first embodiment, the following effects can be obtained.
(1) The acoustic receiving device 30 is provided in a mobile terminal 15 having a microphone 31 and a battery BT, and receives an acoustic signal AS in which an embedded information SC in which an identification information ID is encoded is embedded in the microphone 31. The sound receiving device 30 includes a volume detecting unit 34 that detects the volume of the acoustic signal Sas picked up by the microphone 31, and a determining unit 35 that determines whether or not the detected volume detected by the volume detecting unit 34 exceeds the threshold value. It includes an extraction unit 36 that performs an extraction process for extracting the embedded information SC from the acoustic signal Sas, and a decoding unit 37 that performs a decoding process that decodes the embedded information SC into an identification information ID. The decoding unit 37 performs decoding processing when the detection volume exceeds the threshold value, and does not perform decoding processing when the detection volume is equal to or less than the threshold value. According to this configuration, when the acoustic signal Sas is not received, or when the volume of the acoustic signal Sas is too low and there is a high possibility that the decoding to the identification information ID of the embedded information SC fails, useless decoding is performed. No processing is done. Therefore, the power consumption of the battery BT of the mobile terminal 15 can be reduced. Therefore, the power consumption of the battery BT of the mobile terminal 15 can be suppressed by optimizing whether or not the decoding process is performed.

(2) The volume detection unit 34 calculates the average volume of the acoustic signal Sas per unit time. The determination unit 35 makes a determination by comparing the average volume with the threshold value. According to this configuration, the determination unit 35 compares the average volume with the threshold value for determination. Therefore, even if there is a momentarily low volume part due to breathing of words in the voice included in the acoustic signal Sas or acoustic noise, even if the acoustic signal Sas is decoded by using the average volume per unit time. It is possible to appropriately determine whether or not the volume is appropriate without any problem.

(3) The extraction unit 36 performs extraction processing when the detection volume exceeds the threshold value, and does not perform extraction processing when the detection volume is equal to or less than the threshold value. According to this configuration, when the detection volume of the acoustic signal Sas picked up by the microphone 31 is equal to or lower than the threshold value, the extraction process is not performed in addition to the decoding process. That is, if the acoustic signal Sas is not received, or if the volume of the acoustic signal Sas is too low and there is a high possibility that the decoding to the identification information ID of the embedded information SC fails, the extraction process is performed in addition to the decoding process. Not done. Therefore, the power consumption of the battery BT of the mobile terminal 15 can be further reduced.

(4) The mobile terminal 15 has a display unit 17 and a sound emitting unit such as an earphone jack and a speaker as an output unit for outputting the provided information corresponding to the identification information ID obtained by decoding the embedded information SC by the decoding unit 37. To prepare for. When the detection volume exceeds the threshold value, the provided information corresponding to the identification information ID obtained by decoding by the decoding unit 37 is output to the output unit, and when the detection volume is below the threshold value, the output unit has no provided information. A second control unit 32 for outputting the effect is provided. According to this configuration, when the detection volume exceeds the threshold value, the provided information corresponding to the identification information ID obtained by the decoding by the decoding unit 37 is output to the output unit. On the other hand, when the detection volume is equal to or less than the threshold value, the decoding unit 37 does not perform decoding, and the output unit outputs that there is no provided information. In addition to being able to appropriately provide useful provided information to users, it is possible to reduce errors in which inappropriately provided information is provided due to erroneous decoding. Therefore, the power consumption of the battery BT of the mobile terminal 15 can be appropriately reduced, and useful information can be appropriately provided to the user of the mobile terminal 15.

(5) The embedded information SC in which the same identification information ID is encoded is embedded in the acoustic signal AS a plurality of times in succession. Each time the decoding unit 37 succeeds in decoding, the decoding unit 37 waits without decoding during the first waiting time T1 corresponding to a plurality of consecutive times of the embedded information SC. According to this configuration, even if the microphone 31 receives the acoustic signal Sas, at least decoding is not performed during the predetermined standby time, so that the power consumption of the battery BT can be further reduced. In this case, when the volume exceeds the threshold value, if the embedded information SC succeeds in decoding the first embedded information SC out of a plurality of consecutive times, then the embedded information SC will be used for the remaining number of repetitions. Since the decoding is performed to the same identification information ID, the number of unnecessary decodings can be reduced by waiting without performing the decoding during that time. The predetermined waiting time corresponding to a plurality of times is not limited to the waiting time corresponding to a plurality of times, but may be a waiting time corresponding to one or two times less than the plurality of times.

(6) When the number of consecutive times when the detection volume is determined to be equal to or less than the threshold value by the determination unit 35 reaches the set number of times, the volume detection unit 34 stands by without detecting the detection volume during the second standby time T2. According to this configuration, when the number of consecutive times when the detection volume is determined to be equal to or less than the threshold value reaches the set number of times, the detection volume is not detected during the second standby time T2. When the embedded information SC cannot be correctly decoded due to the noise around the user carrying the mobile terminal 15, not only the decoding is not performed, but also the unnecessary detection volume is not detected and determined. Therefore, the power consumption of the battery BT of the mobile terminal 15 can be further reduced.

(7) A second control unit 32 for detecting the remaining amount of the battery BT is provided. The second control unit 32 has a longer second standby time T2 when the remaining amount of the battery BT is the second remaining amount, which is smaller than the first remaining amount, than when the remaining amount of the battery BT is the first remaining amount. Set to time. According to this configuration, the second standby time T2 is set longer as the remaining amount of the battery BT of the mobile terminal 15 is smaller, and the power consumption of the battery BT can be reduced.

(8) A diffusion method is adopted in which the embedded information SC in which the identification information ID is encoded is diffused into the acoustic signal AS and embedded. The decoding unit 37 decodes the embedded information SC into the identification information ID. Specifically, the embedded information SC is embedded in the acoustic signal AS by an echo diffusion method or a spread spectrum method, and the decoding unit 37 performs decoding processing using the diffusion code. According to this configuration, since the embedded information SC in which the identification information ID is encoded is embedded in the acoustic signal Sa, it is possible to suppress the difficulty in hearing the original sound such as voice and music included in the acoustic signal AS.

(9) The program is executed by a computer provided in the sound receiving device 30 provided in the mobile terminal 15 having the microphone 31 and the battery BT. The acoustic receiving device 30 receives the acoustic signal AS in which the embedded information SC in which the identification information ID is encoded is embedded in the microphone 31. The program uses the computer as a volume detection unit 34 for detecting the volume of the acoustic signal Sas picked up by the microphone 31, a determination unit 35 for determining whether or not the detection volume detected by the volume detection unit 34 exceeds the threshold value, and an acoustic signal. It functions as an extraction unit 36 that extracts the embedded information SC from the Sas, and a decoding unit 37 that decodes the embedded information SC into the identification information ID. The decoding unit 37 decodes the embedded information SC when the detection volume exceeds the threshold value, and does not decode the embedded information SC when the detection volume is equal to or less than the threshold value. By having the computer execute the program, the power consumption of the battery BT of the mobile terminal 15 can be suppressed by optimizing whether or not to decode the embedded information SC.

(10) The information output method in the sound receiving device 30 provided in the portable terminal 15 having the microphone 31, the output unit, and the battery BT includes the following steps. That is, in this method, a volume detection step (S13) for detecting the volume of the acoustic signal Sas picked up by the microphone 31 and a determination step (S14) for determining whether or not the detected volume detected in the volume detection step exceeds the threshold value. ), An extraction step (S15) for extracting the embedded information SC from the acoustic signal Sas, and an output step (S16 to S19). In the output step, if the detection volume exceeds the threshold value, the embedded information SC is decoded into the identification information ID, and the provided information corresponding to the identification information ID is output to the output unit. If the detection volume is below the threshold value, the detection volume is output. The embedded information SC is not decoded and is output to the output unit to the effect that there is no provided information. Therefore, the power consumption of the battery BT of the mobile terminal 15 can be suppressed by optimizing whether or not to decode the embedded information SC.

(Second Embodiment)
Next, the second embodiment will be described with reference to FIGS. 6 and 7. The second embodiment is described above in that whether or not the decoding unit 37 in the sound receiving device 30 continues the decoding process is determined based on the detection result of the volume detection unit 34 and the decoding process result of the decoding unit 37. It is different from the first embodiment. Other configurations of the acoustic communication system 10 are the same as those of the first embodiment. Hereinafter, a configuration different from that of the first embodiment will be mainly described.

As shown in FIG. 6, the sound receiving device 30 built in the mobile terminal 15 has a second control unit 32, a receiving unit 33, a volume detecting unit 34, a determination unit 35, and an extraction unit, as in the first embodiment. A unit 36, a decoding unit 37, a memory 38, and a display processing unit 39 are provided.

The extraction unit 36 extracts the embedded information SC from the acoustic signal Sas that is picked up by the microphone 31, which is an example of the sound collection unit, and is input via the reception unit 33. The volume detection unit 34 inputs the acoustic signal Sas. The volume detection unit 34 detects the volume of the embedded information SC. The determination unit 35 determines whether or not the detection volume detected by the volume detection unit 34 exceeds the threshold value. The decoding unit 37 decodes the embedded information SC into the identification information ID.

In the present embodiment, the volume detection unit 34 detects the volume of the acoustic signal Sas as in the first embodiment. Then, the determination unit 35 determines whether or not the volume of the acoustic signal Sas detected by the volume detection unit 34 exceeds the threshold value. When the determination unit 35 determines that the volume of the acoustic signal Sas exceeds the threshold value, the extraction unit 36 and the decoding unit 37 are activated.

However, even if the volume of the acoustic signal Sas exceeds the threshold value, the embedded information SC may not be embedded in the acoustic signal Sas. Therefore, the determination unit 35 determines the presence / absence of the embedded information SC. For example, in the case of the echo diffusion method, it is difficult to determine the presence / absence of the embedded information SC unless the decoding unit 37 performs the decoding process. Therefore, the determination unit 35 determines the presence / absence of the embedded information SC based on the decoding result information (decoding processing result) of the decoding unit 37. Further, for example, in the case of the spread spectrum method, the presence or absence of the embedded information SC can be determined from the extraction result information (extraction processing result) of the extraction unit 36 without the decoding unit 37 performing the decoding process. Therefore, the determination unit 35 determines the presence / absence of the embedded information SC based on the extraction result information of the extraction unit 36. As described above, the determination unit 35 determines the presence / absence of the embedded information SC based on the decoding result information of the decoding unit 37 or the extraction result information of the extraction unit 36 according to the embedding method of the embedded information SC.

When the determination unit 35 determines the presence / absence of the embedded information SC based on the decoding result information, the decoding result information may be the identification information ID itself. When the identification information ID is input from the decoding unit 37, the determination unit 35 determines that there is embedded information. Further, if the identification information ID is not obtained as a result of the decoding process, the decoding unit 37 sends the decoding result information indicating that fact to the determination unit 35. When the determination unit 35 receives the decoding result information indicating that the identification information ID has not been obtained from the decoding unit 37, the determination unit 35 determines that there is no embedded information. Further, if the decoding result information of the decoding unit 37 is a decoding failure error in which the embedded information SC could not be decoded into the correct identification information ID, the determination unit 35 determines that there is embedded information. This is because decoding may have failed due to temporary noise and an error may have occurred, so it is determined that there is embedded information SC. On the contrary, when the decoding result information of the decoding unit 37 is an error of decoding failure, the determination unit 35 may determine that there is no embedded information.

As a result of the determination, the determination unit 35 outputs the determination value "0" if there is no embedded information SC. As a result, if there is no embedded information SC, the start of the extraction unit 36 and the decoding unit 37 is stopped, or the stopped state thereof is continued. On the other hand, if there is embedded information SC, the determination unit 35 outputs the determination value “1”. In this case, the extraction unit 36 and the decoding unit 37 are activated or the activated state is continued.

At this time, when the determination unit 35 outputs the determination value “0”, the waiting time is set. In this example, for example, the second waiting time T2 is set. Further, the second standby time T2 may be set when the number of consecutive times of determination that there is no embedded information SC reaches a predetermined number of times.

Further, even if there is an embedded information SC, if the noise around the mobile terminal 15 is large, the embedded information SC may not be decoded. Also in this case, the identification information ID cannot be obtained. Even if the decoding fails, the decoding unit 37 sends the decoding result information indicating that there is no identification information ID to the determination unit 35. When the determination unit 35 determines that the decoding has failed based on the decoding result information, if the number of consecutive decoding failures reaches the set number of times, the determination unit 35 outputs the determination value "0" and sets the second standby time T2. You may. The noise around the mobile terminal 15 of this type includes the sound of railways when the user is at the station, the announcement of the station, and the traffic noise when the user is in an area near a high-traffic road such as a car. Examples include conversations with people around the user, such as when the user is in a crowd.

As described above, in the present embodiment, since the presence / absence of the embedded information SC is determined, the embedded information SC cannot be correctly decoded into the identification information ID, not only when the embedded information SC is not embedded in the acoustic signal Sas. Whether or not the volume is low can be appropriately determined. However, in order to determine the presence / absence of the embedded information SC, it is necessary to activate the extraction unit 36 and the decoding unit 37. Further, in order to detect the volume from the signal component of the embedded information SC, it is necessary to activate the extraction unit 36. Therefore, the power consumption required for the extraction unit 36 and the decoding unit 37 tends to be higher than that in the first embodiment. However, in the first embodiment, when the volume of the acoustic signal Sas exceeds the threshold value, the decoding unit 37 continues the decoding process even if the embedded information SC is not embedded in the acoustic signal Sas. On the other hand, in the present embodiment, even when the volume of the acoustic signal Sas exceeds the threshold value, if the embedded information SC is not embedded in the acoustic signal Sas, the activation of the extraction unit 36 and the decoding unit 37 is stopped. Will be done. Therefore, overall, the power consumption of the battery BT can be suppressed as compared with the first embodiment. If the presence / absence of the embedded information SC can be determined based on the embedded information SC extracted by the extraction unit 36, the extraction result information obtained by the extraction unit 36 may be sent to the determination unit 35. In this case, the determination unit 35 activates the decoding unit 37 when it is determined that the embedded information SC is embedded in the acoustic signal Sas based on the extraction result information sent from the extraction unit 36. On the other hand, when the determination unit 35 determines that the embedded information SC is not embedded in the acoustic signal Sas based on the extraction result information sent from the extraction unit 36, the determination unit 35 stops the activation of the decoding unit 37 or sets the stop state. continue.

Next, the operation of the sound receiving device 30 will be described.
Hereinafter, the operation of the sound receiving device 30 driven by the CPU of the mobile terminal 15 by executing the program will be described with reference to FIG. 7. The program is installed in the mobile terminal 15 and corresponds to an application in which a CPU (computer) functions as each unit 32 to 39 constituting the sound receiving device 30. Further, in FIG. 7, steps S11 and S12 common to the first embodiment are omitted. Hereinafter, processing different from that of the first embodiment will be mainly described. Other processes are basically the same as those in the first embodiment.

The user operates the operation unit 16 of the mobile terminal 15 to activate the sound receiving device 30. Upon this activation, the CPU executes the program of the acoustic signal reception processing routine shown in FIG. 7.
The processing of steps S11 to S16 is the same as that of the first embodiment. That is, when the CPU receives the acoustic signal Sas (affirmative determination in step S11), the CPU determines whether or not the standby time has elapsed (step S12). That is, if one of the first standby time T1 and the second standby time T2 has not elapsed (negative determination in step S12), the CPU waits until the standby time elapses. On the other hand, if both the first waiting time T1 and the second waiting time T2 have elapsed, the process proceeds to step S13.

The CPU calculates the average volume (step S13). This process is performed by the volume detection unit 34. The volume detection unit 34 calculates the average volume of the acoustic signal Sas by sampling the volume of the N points per unit time of the acoustic signal Sas, integrating the volumes of the N points, and dividing the total value by N. This step corresponds to an example of a volume detection step.

Then, the CPU determines whether or not the average volume exceeds the threshold value (step S14). This determination is performed by the determination unit 35. If the average volume exceeds the threshold value, the process proceeds to step S15, and if the average volume does not exceed the threshold value, the process proceeds to step S18. Here, if the average volume exceeds the threshold value, the determination unit 35 outputs the determination value “1”, so that the extraction unit 36 and the decoding unit 37 are activated. On the other hand, if the average volume does not exceed the threshold value, the determination unit 35 outputs the determination value "0", so that the extraction unit 36 and the decoding unit 37 are not started or are stopped. In this embodiment, the process of step S14 corresponds to an example of the determination step.

Further, the CPU extracts the embedded information SC (step S15). This process is performed by the extraction unit 36. The extraction unit 36 extracts the embedded information SC from the acoustic signal Sas input from the reception unit 33. The extraction of the embedded information SC is performed by an extraction method according to the diffusion method adopted such as an echo diffusion method or a spread spectrum method. The process of step S15 corresponds to an example of the extraction step.

The CPU executes the decoding process (step S16). This process is performed by the decoding unit 37. The decoding unit 37 decodes the embedded information SC into the identification information ID before encoding by taking a cross-correlation with the same PN sequence as the PN sequence diffused by the embedded information SC with respect to the embedded information SC. do. The decoding unit 37 sends the decoding result information to the determination unit 35, and also sends the decoded identification information ID to the second control unit 32.

In the next step S21, the CPU determines whether or not there is an identification information ID. This process is performed by the determination unit 35. That is, the determination unit 35 determines the presence / absence of the embedded information SC by determining the presence / absence of the identification information ID decoded by the decoding unit 37. That is, it is determined whether or not the embedded information SC is present in the acoustic signal AS. If there is an identification information ID, the CPU proceeds to step S17, and if there is no identification information ID, the CPU proceeds to step S18. In the echo diffusion method, since the presence / absence of the embedded information SC cannot be determined without the decoding process, both the extraction process by the extraction unit 36 and the decoding process by the decoding unit 37 are performed. For example, in the spread spectrum method, if the presence / absence of the embedded information SC can be determined from the acoustic signal AS without the decoding process, the decoding process may not be performed and the extraction process may be performed by the extraction unit 36. For this, the minimum processing that can determine the presence or absence of the embedded information SC may be performed according to the embedded method to be adopted. Further, neither the extraction unit 36 nor the decoding unit 37 may be activated, and the presence or absence of the embedded information SC may be determined by another method.

The processing of steps S17 to S19 is the same as that of the first embodiment shown in FIG. That is, in step S17, the CPU causes the output unit to output the provided information corresponding to the identification information ID. The second control unit 32 acquires the provided information corresponding to the identification information ID by referring to the reference table DT (see FIG. 6) stored in the memory 38 based on the identification information ID. Then, the second control unit 32 displays the provided information on the display unit 17 via the display processing unit 39, or the headphone or earphone connected to the earphone jack by the sound emission processing unit, or the speaker of the mobile terminal 15 (either Also, the provided information is emitted from (not shown).

In step S21, if there is no embedded information SC, the CPU proceeds to step S18. In step S18, the CPU sets the standby time. That is, even when the volume of the acoustic signal Sas exceeds the threshold value, if it is determined that the embedded information SC is not embedded in the acoustic signal Sas, the determination unit 35 outputs the determination value "0". , The activation of the extraction unit 36 and the decoding unit 37 is stopped, or the stopped state is continued. Then, the CPU sets a waiting time for continuing the stopped state. Here, the CPU sets the second standby time T2. Then, in step S19, the CPU outputs to the output unit that there is no identification information ID.

As described in detail above, according to the second embodiment, the effects (4) to (8) in the first embodiment can be obtained in the same manner, and the following effects can be obtained.
(11) The determination unit 35 further determines the presence / absence of the embedded information SC in the acoustic signal Sas, and the decoding unit 37 decodes when it is determined that there is no embedded information SC even if the detection volume exceeds the threshold value. No processing is performed. According to this configuration, the determination unit 35 determines the presence / absence of the embedded information SC in the acoustic signal Sas. If there is no embedded information SC, the decoding process is not performed even if the detection volume exceeds the threshold value. That is, when the embedded information SC is not embedded in the acoustic signal Sas, useless decoding processing is not performed. Therefore, the power consumption of the sound receiving device 30 can be reduced. Therefore, the power consumption of the battery BT of the mobile terminal 15 can be suppressed by optimizing whether or not the decoding process is performed.

(12) The determination unit 35 determines the presence / absence of the embedded information SC based on the extraction processing result by the extraction unit 36 or the decoding processing result by the decoding unit 37. According to this configuration, it is not necessary to separately provide a processing unit for detecting the presence / absence of the embedded information SC, and the presence / absence of the embedded information SC can be accurately determined. Therefore, there are fewer problems that the decoding process is not performed even though the embedded information SC is present, and conversely, the decoding process is performed even though the embedded information SC is not present. Therefore, the power consumption of the battery BT of the mobile terminal 15 can be appropriately reduced.

(13) If it is determined that there is no embedded information SC even if the detection volume exceeds the threshold value, the extraction unit 36 waits without performing the extraction process. Therefore, when it is determined that there is no embedded information even if the detection volume exceeds the threshold value, the decoding unit 37 waits without performing the decoding process, and the extraction unit 36 waits without performing the extraction process. Therefore, the power consumption of the battery BT of the mobile terminal 15 can be further reduced.

The embodiment is not limited to the above, and may be changed to the following aspects.
In each embodiment, the volume determination including the volume detection by the volume detection unit 34 and the determination by the determination unit 35 is performed during the initial activation period in which the acoustic signal AS is first received after the user activates the acoustic receiver 30. It may be executed only for. Further, in addition to the initial startup period of the sound receiving device 30, the volume is not determined in real time, but the volume is determined periodically or irregularly at predetermined time intervals sufficiently longer than the execution cycle of the CPU. May be good. The time interval is, for example, a time in the range of 10 seconds to 10 minutes.

-In each embodiment, the volume detection by the volume detection unit 34 and the determination by the determination unit 35 are executed only during the initial period of activation when the user first activates the acoustic signal AS after activating the acoustic reception device 30. You may.

-In each embodiment, the second control unit 32 detects the remaining amount of the battery BT, and when the remaining amount of the battery BT becomes equal to or less than the remaining amount threshold value, the acoustic signal reception processing routine shown in FIGS. 5 and 7. It may be configured to execute. In this case, the volume detection unit 34, the determination unit 35, the extraction unit 36, and the decoding unit 37 may be constantly activated while the remaining amount of the battery BT exceeds the remaining amount threshold value. The remaining threshold value of the battery BT is, for example, 50%. The remaining amount threshold value is not limited to 50% and may be 70% or 30%.

-In each embodiment, the first standby time T1 may be set as follows. The second control unit 32 counts at the counter how many times the same embedded information SC succeeds out of n consecutive times, and if it succeeds in the pth time, T1 = (n) as the first standby time T1. -P) t may be set.

-In each of the above-described embodiments, the first standby time T1 is set, but the setting of the first standby time T1 may be omitted.
-In each of the above-described embodiments, the second standby time T2 is set, but the setting of the second standby time T2 may be omitted. Further, the second standby time T2 is set when the number of consecutive times when the detection volume is equal to or less than the threshold value reaches the set number of times, but even if the detection volume is once or less than the threshold value, the second standby time T2 may be set. good.

-In the second embodiment, the determination unit 35 may determine the presence / absence of the embedded information SC based on the extraction result information (extraction processing result) of the extraction unit 36. For example, in the case of the spread spectrum method, the signal component of the embedded information SC may be extracted from the acoustic signal Sas, and the presence or absence of the embedded information SC may be determined based on this signal component. According to this configuration, since the determination unit 35 can stop the activation of the decoding unit 37 when determining the presence / absence of the embedded information SC, the power consumption of the battery BT can be further reduced.

-In the second embodiment, the determination unit 35 may only determine the presence / absence of the embedded information SC among the determination of the volume of the acoustic signal and the determination of the presence / absence of the embedded information SC. In this case, if there is no embedded information SC, the decoding unit 37 does not perform the decoding process, so that the power consumption can be suppressed.

-The sound receiving device 30 is not limited to the configuration provided in the mobile terminal 15. The non-portable device may be equipped with the sound receiving device 30. In this case, the non-portable device may not be equipped with a battery and may be configured to receive power from a commercial power source via a cable. Even if the device does not have a battery, the power consumption of the sound receiving device 30 can be suppressed.

-Masking by sound digital watermarking technology is not limited to forward masking, but may be reverse masking.
-The sound digital watermarking method is not limited to the echo diffusion method and the spread spectrum method, and other diffusion methods may be used. As long as the acoustic receiving device 30 includes a decoding unit 37 that decodes the diffusion code, for example, a periodic phase modulation method, a phase multiplexing method, an amplitude modulation method, or the like may be used. Further, the spread spectrum method may be a direct diffusion method or a frequency hopping method.

The diffusion code is not limited to the PN sequence (pseudo-noise sequence), and may be a Gold sequence or the longest sequence (M sequence) obtained by adding two types of PN sequences.

10 ... Sound communication system 11 ... Broadcasting device 12 ... Speaker as an example of sound emitting unit 15 ... Portable terminal 16 ... Operation unit 17 ... Display unit as an example of output unit 20 ... Sound transmitting device 21 ... First input unit 22 ... 2nd input unit 23 ... 1st control unit 26 ... Diffuse code generator 27 ... Encoding unit 28 ... Embedded unit 29 ... Transmitter unit 30 ... Sound receiver 31 ... Microphone as an example of sound pickup unit 32 ... Example of control unit Second control unit 33 ... Reception unit 34 ... Volume detection unit 35 ... Judgment unit 36 ... Extraction unit 37 ... Decoding unit 38 ... Memory 39 ... Display processing unit BT ... Battery DT ... Reference table AS ... Sound signal Sa ... Sound signal OS ... Original sound signal SC ... Embedded information ID ... Identification information T1 ... First standby time T2 ... Second standby time

Claims (12)

It is an acoustic receiver that collects an acoustic signal with embedded information embedded in the sound pickup unit.
A volume detection unit that detects the volume of the acoustic signal collected by the sound collection unit, and a volume detection unit.
A determination unit for determining whether or not the detection volume detected by the volume detection unit exceeds a threshold value, and a determination unit.
An extraction unit that performs extraction processing to extract the embedded information from the acoustic signal,
It is provided with a decoding unit that performs a decoding process that decodes the embedded information into identification information.
The decoding unit is an acoustic receiving device that performs the decoding process when the detected volume exceeds the threshold value and does not perform the decoding process when the detected volume is equal to or lower than the threshold value. The volume detection unit calculates the average volume of the acoustic signal per unit time, and calculates the average volume.
The acoustic receiving device according to claim 1, wherein the determination unit makes a determination by comparing the average volume with the threshold value. The acoustic reception according to claim 1 or 2, wherein the extraction unit performs the extraction process when the detection volume exceeds the threshold value, and does not perform the extraction process when the detection volume is equal to or lower than the threshold value. Device. The determination unit further determines the presence or absence of the embedded information in the acoustic signal, and further determines.
The acoustic according to any one of claims 1 to 3, wherein the decoding unit does not perform the decoding process when it is determined that there is no embedded information even if the detection volume exceeds the threshold value. Receiver. The acoustic receiving device according to claim 4, wherein the determination unit determines the presence or absence of the embedded information based on the extraction processing result by the extraction unit or the decoding processing result by the decoding unit. The acoustic receiving device according to claim 4 or 5, wherein the extraction unit waits without performing the extraction process when it is determined that there is no embedded information even if the detection volume exceeds the threshold value. When the detection volume exceeds the threshold value, the provided information corresponding to the identification information obtained by the decoding by the decoding unit is output to the output unit, and when the detection volume is equal to or less than the threshold value, the output unit is output. The acoustic receiving device according to any one of claims 1 to 6, further comprising a control unit for outputting the fact that there is no provided information. The embedded information in which the same identification information is encoded is embedded in the acoustic signal a plurality of times in succession.
One of claims 1 to 7, wherein the decoding unit waits without decoding during the first waiting time corresponding to the plurality of times in which the embedded information is continuous each time the decoding is successful. The acoustic receiver described in. When the number of consecutive times when the detection volume is determined to be equal to or lower than the threshold value by the determination unit reaches the set number of times, the volume detection unit waits for the second standby time without detecting the detection volume. The acoustic receiving device according to any one of claims 1 to 8. Installed in mobile terminals with batteries
A control unit that detects the remaining battery level is provided.
The control unit sets the second standby time to a longer time when the remaining amount of the battery is the second remaining amount, which is less than the first remaining amount, than when the remaining amount of the battery is the first remaining amount. The acoustic receiver according to claim 9. It is a program to be executed by a computer equipped with an acoustic receiver that collects an acoustic signal with embedded information embedded in the sound pickup unit.
Computer,
A volume detection unit that detects the volume of the acoustic signal collected by the sound collection unit,
A determination unit that determines whether or not the detection volume detected by the volume detection unit exceeds a threshold value.
An extraction unit that extracts the embedded information from the acoustic signal,
If the detected volume exceeds the threshold value, a decoding process that decodes the embedded information into identification information is performed, and if the detected volume is equal to or lower than the threshold value, the decoding unit that does not perform the decoding process.
A program to function as. It is an acoustic signal receiving method in an acoustic receiving device that picks up an acoustic signal in which embedded information is embedded in a sound collecting unit.
A volume detection step for detecting the volume of the acoustic signal collected by the sound collecting unit, and
A determination step for determining whether or not the detected volume detected in the volume detection step exceeds the threshold value, and
An extraction step for extracting the embedded information from the acoustic signal, and
When the detected volume exceeds the threshold value, a decoding process for decoding the embedded information into identification information is performed, and when the detected volume is equal to or lower than the threshold value, an acoustic including a decoding step in which the decoding process is not performed. A method of receiving an acoustic signal in a receiving device.

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