JP5333393B2 - Wireless communication system, transmitter, audio output restriction method, and transmission method - Google Patents

Description

The present invention relates to a radio communication system used for wireless communication of voice signals, the transmitter, audio output limiting method, and a transmission method.

  When transmitting an audio signal via wireless communication, the transmitting-side radio transmits a release signal for effectively outputting the speaker audio in the receiving-side radio, and the receiving-side radio receives the signal. When the cancel signal matches the cancel signal set on the receiving side, audio output from the speaker is permitted. At the start or end of communication, the transmitting-side radio transmits an identification signal indicating the start or end of communication. The receiving-side radio demodulates the identification signal. The identification signal is a digitized signal and is transmitted in the same band as the voice. On the receiving side, when the identification signal is demodulated, it becomes an audible band, and since it is a digitized signal, it is heard as noise.

  Therefore, at the start of communication, the receiving-side radio generates a delay signal from the received release signal, the delay signal is obtained, and the identification information included in the identification signal is held in advance. If they match, a technique for permitting audio output from a speaker has been proposed (for example, Patent Document 1). In such a technique, at the start of communication, since the sound output of the speaker is limited until both the delayed signal and the predetermined identification information are obtained, it is possible to avoid generation of noise due to demodulation of the identification signal as sound. it can.

Japanese Patent No. 3247789

  Incidentally, the generation of noise due to the identification information can occur not only at the start of communication but also at the end of communication. However, since the technique of Patent Document 1 cannot be simply applied at the end of communication, the end identification signal, which is the end identification signal, is demodulated as sound and becomes noise.

In view of this problem, when a communication termination, which can avoid the generation of noise due to the identification signal is demodulated as sound, radio communication system, a transmitter, audio output limiting method, and The purpose is to provide a transmission method .

To solve the above problems, including non-line communication system and a receiver for audio output by receiving a radio signal transmitted from the transmitter and a transmitter for transmitting a radio signal modulated audio signal of the present invention ,
The transmitter includes a restriction signal generation unit that generates a release signal for restricting the output restriction on the audio output in the receiver and an enabling signal that enables the output restriction, and an identification signal indicating unique information of the transmitter An identification signal generation unit that generates a transmission signal, a transmission unit that transmits an audio signal, an identification signal, a cancellation signal, and an activation signal, and an activation signal after the transmission unit stops transmitting the cancellation signal at the end of transmission And a transmission control unit for transmitting an identification signal after transmitting an enabling signal, and
The receiver receives the audio signal, the identification signal, the release signal, and the enable signal transmitted from the transmitter, and cancels the output restriction on the audio output while receiving the release signal, and activates the receiver. And a restriction release unit that activates the output restriction on the audio output when receiving the activation signal.

In order to solve the above problems, Shin machine transmission that sends a radio signal obtained by modulating the audio signals to the receiver of the present invention, the release signal for limiting the output limit according to the audio output of the receiver and the output A limiting signal generating unit that generates an enabling signal that enables limiting, an identification signal generating unit that generates an identifying signal indicating unique information of the transmitter, an audio signal, an identifying signal, a release signal, and an enabling signal; A transmission unit that transmits the activation signal after stopping the transmission of the release signal to the transmission unit at the end of transmission, and the transmission control unit that transmits the identification signal after transmitting the activation signal, It is characterized by providing.

In order to solve the above-described problems, the audio output of the receiver in communication between the transmitter that transmits a radio signal modulated from the audio signal of the present invention and the receiver that receives the radio signal transmitted from the transmitter and outputs the audio. In the audio output restriction method to restrict
The transmitter generates a release signal for releasing the output restriction on the audio output at the receiver and an enable signal for enabling the output restriction , generates an identification signal indicating the unique information of the transmitter, and releases the release signal. transmits a signal and an audio signal, it stops transmission of the release signal, transmits an activation signal,
Send an identification signal,
The receiver receives the audio signal, the identification signal, the release signal, and the enable signal transmitted from the transmitter. While receiving the release signal, the receiver cancels the output restriction on the audio output and sends the enable signal. It is characterized in that the output restriction concerning the audio output is made effective when received .
In order to solve the above-described problem, in a transmission method of a transmitter that transmits a radio signal obtained by modulating an audio signal to a receiver according to the present invention, a release signal for limiting an output restriction on audio output in the receiver; Generating an activation signal that activates the output restriction, generating an identification signal indicating the unique information of the transmitter, transmitting a release signal and an audio signal, stopping transmission of the release signal, and After the transmission, an identification signal is transmitted.

  The wireless device of the present invention can avoid the generation of noise due to the identification signal being demodulated as sound at the end of communication.

It is explanatory drawing for demonstrating a radio | wireless communications system. It is the functional block diagram which showed the electric structure of the radio | wireless machine. It is explanatory drawing for demonstrating the flow of a process at the time of a communication start. It is explanatory drawing for demonstrating the flow of the process at the time of the completion | finish of communication. It is explanatory drawing for demonstrating the flow of the other process at the time of completion | finish of communication. It is a sequence diagram which shows the flow of a process of an audio | voice output restriction method.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in the embodiments are merely examples for facilitating understanding of the invention, and do not limit the present invention unless otherwise specified. In the present specification and drawings, elements having substantially the same function and configuration are denoted by the same reference numerals, and redundant description is omitted, and elements not directly related to the present invention are not illustrated. To do.

(Wireless communication system 100)
FIG. 1 is an explanatory diagram for explaining the radio communication system 100. In particular, FIG. 1A shows a case where an identification signal is used, and FIG. 1B shows a case where an identification signal is not used. As shown in FIG. 1A, the wireless communication system 100 includes a wireless device 110 (indicated by 110a, 110b, and 110c in the figure) and a recording device 112.

  Here, the radio 110a functions as a transmitter, collects a voice uttered by a user, generates a voice signal, modulates the voice signal, superimposes it on a carrier wave, and transmits it as a radio wave. Here, the radios 110b and 110c function as receivers. In particular, the radio 110c also functions as a management device used by the administrator, and the radio 110a transmits in accordance with the frequency of the carrier wave and the tone signal described later. The received radio wave is received, the audio signal is demodulated, and output from the speaker as audio.

  However, for example, as shown in FIG. 1B, when the wireless device 110a simply transmits an audio signal, the wireless devices 110b and 110c determine which wireless device 110 the audio signal is transmitted from. I can't. This makes it impossible to manage the wireless device 110 by the management device (wireless device 110c).

  Therefore, as shown in FIG. 1A, the transmitter-side radio 110a starts to indicate ID (IDentification), which is unique information assigned to the radio 110a prior to the audio signal, at the start of communication. An identification signal (BOT: Beginning Of Transmission) is transmitted, and at the end of communication, an end identification signal (EOT: End Of Transmission) indicating ID, which is unique information assigned to the radio 110a, is transmitted after the voice signal. To do.

  When the wireless device 110c as the management device receives the identification signal (start identification signal, end identification signal) transmitted from the wireless device 110a, the wireless device 110c identifies whether the identification signal is a start identification signal or an end identification signal. The ID indicated in the signal and the date and time when the identification signal is received are output to the recording device 112.

  The recording device 112 is, for example, a personal computer, and records the ID, date, and time output from the wireless device 110c as a log in an internal memory (not shown). In this way, by leaving a log, it becomes possible to confirm later when and how long the wireless device 110 has been transmitting. Further, when receiving the start identification signal, the radio device 110b on the receiving side displays the ID indicated in the start identification signal on the display unit 116 configured by a liquid crystal display (LCD) or the like.

  The identification signal is a digitized signal. Since the transmitting side radio transmits the identification signal in the same band as the voice, the demodulated identification signal becomes an audible band in the receiving side radio. Therefore, even the identification signal is demodulated as sound, and as a result, it is output as noise.

  Therefore, the present embodiment proposes a radio communication system 100, a radio 110, and an audio output restriction method that can avoid the generation of noise due to the demodulation of the identification signal as sound at the start and end of communication. . Hereinafter, the configuration of the wireless device 110 common to the wireless devices 110a and 110b will be described in detail, then the processing at the start of communication and the end of communication will be described in detail, and the audio output restriction method using the wireless device 110 Will be explained.

(Radio 110)
FIG. 2 is a functional block diagram showing an electrical configuration of the wireless device 110. Radio 110 includes operation unit 120, sound collection unit 122, MSK (Minimum-Shift Keying) encoder 124, tone encoder 126, transmission unit 128, central control unit 130, antenna switch 132, and antenna 134. A receiving unit 136, an LPF (Low Pass Filter) 138, a tone decoder 140, an HPF (High-Pass Filter) 142, an MSK decoder 144, an audio switch 146, an output amplifier 148, and a speaker 150. Consists of including. In FIG. 2, solid arrows indicate data and signal flows, and broken arrows indicate power flows.

  The operation unit 120 includes operation keys, a cross key, a joystick, and the like, and accepts user operation inputs. The sound collection unit 122 is composed of a microphone or the like, converts air vibrations such as sound into sound signals, and outputs the sound signals to the transmission unit 128.

  The MSK encoder 124 functions as an identification signal generation unit, generates a start identification signal and an end identification signal based on the MSK modulation scheme, and outputs them to the transmission unit 128. The MSK modulation scheme is a kind of FSK (Frequency Shift Keying) modulation scheme, and is a modulation scheme that minimizes the frequency shift of FSK. By adopting the MSK modulation method, frequency modulation and demodulation resistant to noise can be realized with a simple configuration. In the present embodiment, the MSK modulation method is used. However, the present invention is not limited to this, and FSK, DPSK (Differential Phase Shift Keying), BPSK (Binary Phase Shift Keying), QPSK (Quadrature Phase Shift Keying), 8PSK, 16QAM (Quadrature). Various modulation schemes such as Amplitude Modulation) and 64QAM can also be used.

  The tone encoder 126 functions as a limit signal generation unit, generates a cancel signal for canceling the output limit for audio output in the radio device 110b on the reception side, and outputs the signal to the transmission unit 128. In the present embodiment, the release signal is a tone signal such as a CTCSS (Continuous Tone Coded Squelch) signal or a DCS (Digital Code Squelch) signal used for the tone squelch function. Here, the CTCSS is a continuous single tone of 300 Hz or less, and the DCS is a tone obtained by digitally extending the number because the number of CTCSS is limited (at most 40 waves). Further, the tone encoder 126 generates not only a release signal but also an enable signal for re-enabling the output restriction in response to the stop of the release signal transmission. The enabling signal is a tone signal having the same frequency as the cancellation signal, but has a different phase. The validation signal is transmitted following the release signal.

  The transmission unit 128 performs FM (Frequency Modulation) modulation on the antenna switch 132 by superimposing the start identification signal, the audio signal, the end identification signal, and the release signal on a carrier wave by a mixer (not shown). Output.

  The central control unit 130 includes a central processing unit (CPU), a signal processing unit (DSP: Digital Signal Processor), a ROM and memory storing programs, a semiconductor integrated circuit including a RAM as a work area, and the like. Manage and control the entire machine 110. The central control unit 130 also functions as a transmission control unit 160, a display control unit 162, and a restriction release unit 164.

  The transmission control unit 160 causes the tone encoder 126 to transmit a release signal after transmitting the start identification signal to the MSK encoder 124 when transmission of the audio signal is started and completing the transmission. In addition, when the transmission of the audio signal is finished, the transmission control unit 160 stops the transmission of the release signal by the tone encoder 126, generates an enabling signal, transmits the enabling signal, and then ends the MSK encoder 124. An identification signal is transmitted.

  When the start identification signal is included in the signal output from the MSK decoder 144 described later, the display control unit 162 causes the display unit 116 to display the ID of the transmitter-side radio 110a indicated by the start identification signal.

  The restriction release unit 164 determines whether or not a release signal or an enable signal has been received based on an output from the tone decoder 140 described later, and while receiving a release signal of a preset frequency, the voice switch 146. Is controlled (closed), and the audio signal input to the audio switch 146 is output to the speaker 150, thereby releasing the output restriction on the audio output. Further, if the release signal is not received or the activation signal is received while the output restriction is being released, the restriction release unit 164 controls (opens) the voice switch 146 and the voice switch 146. By blocking the audio signal input to, the output restriction on the audio output is validated.

  The antenna switch 132 switches between radio wave transmission and reception according to the control of the central control unit 130. The antenna 134 can convert the carrier wave output from the transmission unit 128 into a radio wave and transmit the radio wave to the reception-side radio 110b, or conversely, the reception unit 136 can process the radio wave received from the transmission-side radio 110a. Or convert to a wireless signal.

  The receiving unit 136 demodulates the radio signal converted by the antenna 134 by removing the carrier wave through a mixer (not shown) and an LPF (not shown), and a start identification signal, an audio signal, an end identification signal, and a cancellation signal (further, Take the activation signal). The LPF 138 extracts a cancellation signal or an activation signal by removing a frequency component higher than a predetermined frequency (for example, 300 Hz).

  When the signal extracted by the LPF 138 matches the frequency of the preset release signal, the tone decoder 140 outputs a message to that effect to the restriction release unit 164. Further, when the signal extracted by the LPF 138 is an activation signal, the tone decoder 140 outputs a message to that effect to the restriction release unit 164.

  The HPF 142 removes frequency components below a predetermined frequency, extracts only the start identification signal, the audio signal, and the end identification signal, and outputs them to the MSK decoder 144 and the audio switch 146. The MSK decoder 144 demodulates the signal extracted by the HPF 142 based on the MSK modulation method, and converts the signal extracted by the HPF 142 into a signal that can be read by the central control unit 130 when the signal is the start identification signal or the end identification signal. The data is output to the central control unit 130. When the signal extracted by the HPF 142 is an audio signal, the MSK decoder 144 does not output a signal to the central control unit 130.

  For example, when the wireless device 110 functions as a management device, the central control unit 130 determines that the identification signal is a start identification based on the signal received from the MSK decoder 144 in order to leave a log as in the wireless device 110c described above. Whether it is a signal or an end identification signal, the ID indicated in the identification signal, and the date and time when the identification signal is received are output to the recording device 112.

  The audio switch 146 limits (cuts) the audio output of the speaker 150 in accordance with the control command from the restriction release unit 164. The output amplifier 148 amplifies the output signal of the audio switch 146. The speaker 150 outputs the signal amplified by the output amplifier 148 as sound.

  FIG. 3 is an explanatory diagram for explaining the flow of processing at the start of communication. In particular, FIG. 3A shows a case where the transmission timings of the start identification signal and the release signal are changed, and FIG. 3B shows a conventional example. 3A and 3B, a period indicated by a double-headed arrow 170 is a delay time required from when the MSK encoder 124 starts preparation for generating the start identification signal to when the transmission unit 128 starts transmitting the start identification signal. (TX Modulation Delay Time).

  As shown in FIG. 3B, when the user turns on the transmission switch (PTT: Push To Talk) of the operation unit in the radio, the transmission control unit first causes the tone encoder 126 to transmit a release signal, After the elapse of the period indicated by the arrow 170, the MSK encoder 124 is instructed to transmit a start identification signal to transmit the start identification signal.

  In this case, the reception-side radio device 110b receives the release signal first, causes the restriction release unit 164 to release the restriction on the audio output, and then receives the start identification signal. For this reason, the speaker 150 of the radio device 110b on the receiving side outputs noise that is demodulated using the start identification signal as sound.

  On the other hand, as shown in FIG. 3A, in this embodiment, the transmission control unit 160 instructs the MSK encoder 124 to transmit a start identification signal, causes the start identification signal to be transmitted, and after the transmission is completed. The tone encoder 126 transmits a release signal. For this reason, the receiving radio 110b does not receive the release signal even while receiving the start identification signal, so the voice switch 146 limits the voice output, and the start identification signal is used as a sound. Demodulated noise is not output.

  Next, processing at the end of communication will be described. FIG. 4 is an explanatory diagram for explaining the flow of processing at the end of communication. In particular, FIG. 4A shows a case where the transmission timings of the end identification signal and the release signal are changed, and FIG. 4B shows a conventional example.

  As shown in FIG. 4B, in the conventional example, when the user turns off the transmission switch of the radio, the transmission control unit causes the MSK encoder to transmit the end identification signal while causing the tone encoder to transmit the release signal. A transmission instruction is issued to transmit an end identification signal.

  In this case, the reception-side radio device 110b receives the end identification signal while continuing to receive the release signal. For this reason, the speaker 150 of the radio device 110b on the receiving side outputs noise that is demodulated with the end identification signal as sound for the transmission time of the end identification signal.

  On the other hand, in the case shown in FIG. 4A, the transmission control unit 160 stops the transmission of the release signal to the tone encoder 126, then instructs the MSK encoder 124 to transmit the end identification signal, and ends the end identification signal. To send. Therefore, when receiving the end identification signal, the receiving radio 110b has not received the release signal and the voice switch 146 restricts the sound output, so that the end identification signal is demodulated as sound. Noise is not output.

  When transmission is performed by the wireless device 110 of the present embodiment, output of noise due to demodulation of the end identification signal as sound can be avoided in the receiving wireless device 110b. Further, since the transmission unit 128 maintains the release signal until the end identification signal is output, the normal audio signal is not blocked.

  Furthermore, since the wireless device 110 is simply configured to advance the timing for terminating the transmission of the release signal, it does not require a major change of the existing wireless device, and only changes the transmitting-side wireless device 110a. Since it is realizable, it is possible to implement | achieve the radio | wireless communications system 100 at low cost.

  In the example of FIG. 4A, the audio output of the speaker 150 is stopped when the release signal is not received. However, depending on the communication environment, the reception strength may be low, so if the sound output from the speaker 150 is strictly stopped when the release signal is not received, the call is frequently interrupted. For this reason, even if the release signal is no longer received, the audio output is not stopped immediately, and the audio output from the speaker 150 is maintained for a predetermined time. In this case, since it is difficult to determine whether the release signal is not received due to the communication environment or intentional communication termination, it is possible to determine the intentional communication termination by taking a predetermined time. Will be. However, if the predetermined time is too long, it may be difficult to stop the sound output from the speaker 150 even if the communication is intentionally terminated.

  FIG. 5 is an explanatory diagram for explaining another processing flow at the end of communication. In the present embodiment, as shown in FIG. 5, the tone encoder 126 generates and transmits an activation signal 172 that is different in phase (shifted in phase) from the cancellation signal for cutting off the audio output. Then, it is notified to the radio device 110b on the receiving side that it indicates intentional communication termination. In this way, the radio apparatus 110b on the receiving side can reliably and quickly end the communication, and can avoid the occurrence of noise due to the end identification signal. In addition, when the transmission switch of the wireless device 110a on the transmission side is turned off, noise signals such as a squelch tail may be generated due to the absence of operation sound or sound of the transmission switch. With the configuration in which the validation signal 172 is transmitted, it is possible to avoid a situation in which this noise signal is also output as noise by the radio device 110b on the receiving side.

  In addition, the transmission control unit 160 waits for a predetermined time longer than a predetermined time from when the activation signal 172 is started to be transmitted until the output restriction of the radio device 110b on the reception side is activated again. The MSK encoder 124 may be instructed to transmit an end identification signal to transmit the end identification signal.

  In this way, the transmission control unit 160 waits for a predetermined time and then causes the MSK encoder 124 to generate an end identification signal. For example, the receiving-side radio 110b receives the enable signal 172, and the output restriction is resumed. Even when it takes time to activate, since the end identification signal is received after the activation of the output restriction is completed, generation of noise due to the end identification signal can be avoided more reliably.

(Audio output restriction method)
Next, an audio output restriction method using the wireless device 110 will be described. FIG. 6 is a sequence diagram showing the flow of processing of the audio output restriction method.

  At the start of communication, when the user turns on the transmission switch of the radio 110a, the transmission control unit 160 causes the MSK encoder 124 to generate a start identification signal (S200), and causes the transmission unit 128 to superimpose the start identification signal on the carrier wave. (S202) and transmit (S204).

  In the receiving-side radio device 110b, when the receiving unit 136 receives the start identification signal (S206), the display control unit 162 causes the display unit 116 to display the ID of the transmitting-side radio device 110a indicated by the start identification signal. (S208).

  Subsequently, in the radio device 110a on the transmission side, the tone encoder 126 generates a release signal (S210), the sound collection unit 122 generates an audio signal (S212), and the transmission control unit 160 transmits to the transmission unit 128. Then, the audio signal and the release signal are superimposed on the carrier wave (S214), and are transmitted to the radio device 110b on the receiving side (S216).

  In the radio device 110b on the receiving side, when the receiving unit 136 receives the audio signal and the release signal (S218), the restriction release unit 164 outputs the output related to the audio output while receiving the release signal of the preset frequency. The restriction is continuously released and the audio signal input to the audio switch 146 is output to the speaker 150 (S220). The speaker 150 outputs the audio signal as audio (S222).

  When the transmission switch of the wireless device 110a on the transmission side is turned off, the transmission control unit 160 causes the transmission unit 128 to stop transmitting the audio signal (S224), stop transmitting the release signal (S226), and the tone encoder 126. Generates an enabling signal 172 (S228). Then, the transmission control unit 160 causes the tone encoder 126 to transmit the validation signal 172 (S230).

  In the receiving radio 110b, when the receiving unit 136 receives the activation signal 172 (S232), the restriction releasing unit 164 controls the voice switch 146 to block the voice signal input to the voice switch 146. Then, the output restriction related to the audio output is validated (S234).

  Then, the MSK encoder 124 of the radio device 110a on the transmitting side generates an end identification signal (S236), and the transmission control unit 160 instructs the MSK encoder 124 to transmit the end identification signal and causes the end identification signal to be transmitted. (S238) In the receiving-side radio 110b, the receiving unit 136 receives the end identification signal (S240), and the display control unit 162 indicates the ID to the display unit 116 when the received signal indicates the end identification signal. The display is terminated (S242).

  Thus, by using the audio output restriction method described above, it is possible to avoid the generation of noise due to the identification signal being demodulated as sound at the end of communication.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to this embodiment. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Is done.

  It should be noted that each step of the audio output restriction method of the present specification does not necessarily have to be processed in time series in the order described as a sequence diagram, and may include parallel or subroutine processing.

The present invention is applicable wireless communication system used for wireless communication, transmitters, voice output limiting method, and transmission method.

100 ... Wireless communication system 110 (110a, 110b) ... Radio (transmitter, receiver)
122 ... Sound collection unit 124 ... MSK encoder (identification signal generation unit)
126 ... tone encoder (release signal generator)
128 ... transmission unit 136 ... reception unit 160 ... transmission control unit 164 ... restriction release unit 172 ... validation signal

Claims (4)

A wireless communication system including a transmitter that transmits a wireless signal obtained by modulating an audio signal, and a receiver that receives the wireless signal transmitted from the transmitter and outputs the sound.
The transmitter is
A limit signal generator for generating a release signal for limiting the output limit for the audio output in the receiver and an enabling signal for enabling the output limit;
An identification signal generator for generating an identification signal indicating unique information of the transmitter;
A transmitter that transmits the audio signal, the identification signal, the release signal, and the validation signal;
A transmission control unit for generating the enabling signal after stopping transmission of the release signal to the transmitting unit at the end of transmission, and transmitting the identification signal after transmitting the enabling signal;
With
The receiver
A receiver that receives the audio signal, the identification signal, the release signal, and the validation signal transmitted from the transmitter;
While receiving the release signal, cancel the output restriction on the sound output, and when receiving the validation signal, a restriction release unit that enables the output restriction on the sound output;
A wireless communication system comprising: A transmitter for transmitting a radio signal obtained by modulating an audio signal to a receiver,
A limit signal generator for generating an enable signal to enable release signal and the output limit to limit the output limit according to Ruoto voice output put to the receiver,
An identification signal generator for generating an identification signal indicating unique information of the transmitter;
A transmitter that transmits the audio signal, the identification signal, the release signal, and the validation signal;
A transmission control unit for generating the enabling signal after stopping transmission of the release signal to the transmitting unit at the end of transmission, and transmitting the identification signal after transmitting the enabling signal;
A transmitter comprising: An audio output limiting method for limiting an audio output of a receiver in communication between a transmitter that transmits a radio signal obtained by modulating an audio signal and a receiver that receives the radio signal transmitted from the transmitter and outputs the audio. ,
The transmitter is
Generating a release signal for releasing the output restriction on the audio output in the receiver and an enabling signal for enabling the output restriction ;
Generating an identification signal indicating unique information of the transmitter;
Transmits the release signal and the said audio signal,
To stop the transmission of the previous SL release signal,
Sending the enabling signal;
Transmitting the identification signal;
The receiver
Receiving the audio signal, the identification signal, the release signal, and the validation signal transmitted from the transmitter;
While receiving the release signal, cancel the output restriction on the audio output ,
An audio output restriction method, wherein an output restriction on the audio output is validated when the validation signal is received .   A transmitter transmission method for transmitting a radio signal obtained by modulating an audio signal to a receiver,
  Generating a release signal for limiting an output limit for audio output in the receiver and an enabling signal for enabling the output limit;
  Generating an identification signal indicating unique information of the transmitter;
  Transmitting the release signal and the audio signal;
  Stop sending the release signal,
  A transmission method comprising transmitting the identification signal after transmitting the validation signal.

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