FM disaster prevention administrative radio transmission system and FM disaster prevention administrative radio transmission method

Abstract

To provide an FM disaster prevention administrative radio transmission system and an FM disaster prevention administrative radio transmission method that enable reliable listening of disaster prevention administrative radio audio information in FM broadcasting.SOLUTION: An FM transmitter 4 receives a digital audio signal from a loudspeaker slave station 3, converts the digital audio signal into an analog audio signal, and transmits, via an antenna, an FM signal obtained by FM-modulating the analog audio signal.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a technique for providing audio information for disaster prevention administrative radio transmission from an FM transmitter used in an FM disaster prevention administrative radio transmission system. [Background technology]

[0002] In response to the increasing number of disasters in recent years, a system called the "FM Disaster Prevention Information System" is being considered. This system is being discussed by the "Working Group on Disaster Prevention Use of the V-Low Band" of the Subcommittee on Utilization of Broadcasting Frequencies held by the Ministry of Internal Affairs and Communications, and specifically, the system aims to provide vehicle evacuees and vehicles stranded due to heavy snowfall with audio information that is the same as that provided by outdoor loudspeaker stations of the disaster prevention administrative radio system, using commercially available radio receivers (such as car radio receivers), to those who have difficulty hearing the audio information provided by outdoor loudspeaker stations of the disaster prevention administrative radio system. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] "About the FM Disaster Prevention Information System" 1st edition, October 2021, Working Group on Disaster Prevention Use of V-Low Band, Ad Hoc Group Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the conventional FM disaster prevention administrative radio transmission system 101 introduced in the above-mentioned "FM disaster prevention information system", as shown in FIG. 6, when the loudspeaker slave station 103 receives the disaster prevention administrative radio wave from the master station 2 at the receiver, the demodulator separates the radio wave into a carrier wave and a digital audio signal, the codec converts the digital audio signal to an analog audio signal, and the audio amplifier amplifies the analog audio signal before transmitting it to the FM transmitter 104, which performs FM modulation and outputs it from the antenna. In other words, the conventional FM transmitter 104 transmits the analog audio delivered from the loudspeaker slave station 103 as it is by FM radio wave, so the audio quality remains at the same level as the original disaster prevention administrative radio. Moreover, since noise is generated by the exchange of analog audio, the audio quality is further deteriorated. Therefore, improving the quality of the audio output from the FM transmitter has been an issue.

[0005] Therefore, an object of the present invention is to provide an FM disaster prevention administrative radio transmission system and an FM disaster prevention administrative radio transmission method that enable audio information of the disaster prevention administrative radio to be reliably heard over FM broadcasts. [Means for solving the problem]

[0006] In order to solve the above problem, the invention described in claim 1 is an FM disaster prevention administrative radio transmission system comprising a loudspeaker substation that demodulates a disaster prevention administrative radio signal received from a parent station into a digital audio signal, converts the digital audio signal into an analog audio signal, and outputs the analog audio signal through a speaker, and an FM transmitter connected to the loudspeaker substation, wherein the FM transmitter receives the digital audio signal from the loudspeaker substation, converts the digital audio signal into an analog audio signal, and transmits the FM signal obtained by FM modulating the analog audio signal through an antenna.

[0007] The invention described in claim 2 is the FM disaster prevention administrative radio transmission system described in claim 1, characterized in that the FM transmitter is equipped with a control means, an audio adjustment circuit, and an information storage means, and the control means adjusts the audio of the digital audio signal received from the loudspeaker substation in the audio adjustment circuit and transmits the digital audio signal after audio adjustment to the information storage means, and the information storage means stores the digital audio signal after audio adjustment and outputs the digital audio signal for conversion to the analog audio signal upon output instruction from the control means.

[0008] The invention described in claim 3 is an FM disaster prevention administrative radio transmission system described in claim 2, characterized in that the FM transmitter is equipped with a parameter storage means, and the parameter storage means stores parameters related to the audio adjustment in the audio adjustment circuit and parameters related to the output of the digital audio signal included in the output instruction.

[0009] The invention described in claim 4 is an FM disaster prevention administrative radio transmission system described in any one of claims 1 to 3, characterized in that the FM transmitter is equipped with a silence detection means for detecting the presence or absence of input of the digital audio signal from the loudspeaker substation, and the silence detection means starts the FM transmitter when it detects input of the digital audio signal.

[0010] The invention described in claim 5 is an FM disaster prevention administrative radio transmission method executed by an FM disaster prevention administrative radio transmission system including a loudspeaker substation that demodulates a disaster prevention administrative radio signal received from a parent station into a digital audio signal, converts the digital audio signal into an analog audio signal, and outputs the analog audio signal through a speaker, and an FM transmitter connected to the loudspeaker substation, characterized in that the FM transmitter has a step of receiving the digital audio signal from the loudspeaker substation and converting the digital audio signal into an analog audio signal, and a step of transmitting the FM signal obtained by FM modulating the analog audio signal through an antenna. Effect of the Invention

[0011] According to the inventions of claims 1 and 5, the FM transmitter receives a digital audio signal from the loudspeaker slave station, so that noise that occurs during the exchange of analog audio signals can be suppressed, thereby making it possible to improve the quality of the audio output from the FM transmitter.

[0012] According to the invention of claim 2, since the FM transmitter stores the digital audio signal, the number of FM broadcasts and the transmission timing can be easily adjusted, and it becomes possible to increase the opportunities for people who miss real-time FM broadcasts to receive the disaster prevention administrative radio broadcast later. Also, since the audio is adjusted by the audio adjustment circuit to have the desired physical properties such as frequency, volume, playback speed, etc., and then stored, it becomes possible to transmit disaster prevention administrative radio broadcasts that have been adjusted to be easy to hear.

[0013] According to the invention of claim 3, parameters related to audio adjustment when adjusting a digital audio signal and parameters related to the output of a digital audio signal from an information storage means are stored in a parameter storage means, making it easier to control audio adjustment and FM broadcast transmission.

[0014] According to the invention of claim 4, since the FM transmitter is equipped with a silence detection means, even if the loudspeaker slave station does not have a function for coordinating with the FM transmitter, it is possible to start the FM transmitter in response to the input of a digital audio signal. [Brief description of the drawings]

[0015] [Figure 1] 1 is a schematic diagram showing the configuration of an FM disaster prevention administrative radio transmission system in accordance with embodiment 1 of the present invention. [Diagram 2] 1 is a schematic diagram showing the configuration of an FM disaster prevention administrative radio transmission system in accordance with embodiment 2 of the present invention. [Diagram 3] 10 is a schematic diagram showing the configuration of an FM disaster prevention administrative radio transmission system in accordance with embodiment 3 of the present invention. FIG. [Figure 4] 4 is a flowchart showing a processing procedure in the FM transmitter used in the first and second embodiments (FIG. 4-1: first embodiment, FIG. 4-2: second embodiment). [Diagram 5] 5 is a flowchart showing a processing procedure in the FM transmitter used in the third embodiment (FIG. 5-1: when voice input is detected, FIG. 5-2: when silence is detected). [Figure 6] FIG. 1 is a schematic diagram showing the configuration of a conventional FM disaster prevention administrative radio transmission system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, the present invention will be described based on the illustrated embodiment.

[0017] (Embodiment 1) 1 is a schematic diagram showing the configuration of an FM disaster prevention administrative radio transmission system 1 according to a first embodiment of the present invention. The FM disaster prevention administrative radio transmission system 1 according to the present embodiment executes the FM disaster prevention administrative radio transmission system and the FM disaster prevention administrative radio transmission method of the present invention. Note that the FM disaster prevention administrative radio transmission system 1 of the present invention is a system that complements, rather than changes, the disaster prevention administrative radio transmission system operated by a local government or administration.

[0018] The FM disaster prevention administrative radio transmission system 1 includes a master station 2, loudspeaker slave stations 3, and an FM transmitter 4. The master station 2 is a base station for disaster prevention administrative radio installed in a municipal office or the like of a local government, and transmits radio waves for the disaster prevention administrative radio to the multiple loudspeaker slave stations 3.

[0019] A plurality of loudspeaker slave stations 3 are installed in a dispersed manner within the jurisdiction (target area) of the master station 2. When the loudspeaker slave station 3 receives radio waves of the disaster prevention administrative radio from the master station 2 at its receiver, the demodulator separates the radio waves into a carrier wave and a digital audio signal, the decoder expands the signals, the D / A converter converts the digital audio signal into an analog audio signal, the audio amplifier amplifies the analog audio signal, and outputs it through the installed speaker.

[0020] Moreover, the loudspeaker slave station 3 is connected to an FM transmitter 4, and transmits a digital audio signal obtained by a demodulator to the FM transmitter 4. When the FM transmitter 4 receives the digital audio signal from the loudspeaker slave station 3, it converts the digital audio signal into an analog audio signal in a D / A converter, FM-modulates the analog audio signal in an FM modulation circuit, and amplifies the FM signal obtained by FM modulation in an amplifier or the like and transmits it via an antenna.

[0021] Next, the operation of the FM transmitter 4 according to the above-mentioned embodiment 1 will be described with reference to the flow chart shown in Fig. 4-1. The FM transmitter 4 is started in response to an activation signal outputted from the audio amplifier of the loudspeaker slave station 3 to activate the speaker, for example, and receives a digital audio signal from the loudspeaker slave station 3. The FM transmitter 4 converts the received digital audio signal into an analog audio signal in a D / A converter (step Sa1). Next, the FM modulation circuit FM-modulates the analog audio signal, and the FM signal obtained by FM modulation is amplified in an amplifier or the like and transmitted by an antenna (step Sa2).

[0022] As described above, in the FM disaster prevention administrative radio transmission system 1 of this embodiment, the FM transmitter 4 receives a digital audio signal from the loudspeaker station 3, so that noise that occurs during the exchange of analog audio signals can be suppressed, making it possible to improve the quality of the audio output from the FM transmitter 4.

[0023] (Embodiment 2) FIG. 2 is a schematic diagram showing the configuration of an FM disaster prevention administrative radio transmission system 1 in accordance with embodiment 2 of the present invention.

[0024] In the conventional FM disaster prevention administrative radio transmission system 101 shown in Fig. 6, the audio information of the disaster prevention administrative radio provided through the loudspeaker slave station 103 is broadcast in real time via FM, so even if the radio is tuned to the frequency of the FM disaster prevention information system when the audio of the disaster prevention administrative radio is not being broadcast, the audio information of the disaster prevention administrative radio cannot be obtained. Therefore, there was a problem that those who missed the FM broadcast for some reason or those who could not hear it well could not check the audio information of the disaster prevention administrative radio later.

[0025] In order to solve the above problems, the FM disaster prevention administrative radio transmission system 1 in this embodiment differs from the above-mentioned embodiment 1 in that the FM transmitter 4 has a configuration for storing digital audio signals. However, other configurations are the same as those in the above-mentioned embodiment 1, and therefore the same symbols are used for the configurations that are the same as those in the above-mentioned embodiment 1, and their explanations will be omitted.

[0026] This embodiment is characterized in that the FM transmitter 4 has a function of storing the digital audio signal of the disaster prevention administrative radio broadcast so that people who miss the real-time FM broadcast can check the audio information of the disaster prevention administrative radio broadcast later. To realize this function, the FM transmitter 4 has a control unit (control means) 5 and an information storage unit (information storage means) 6.

[0027] When the control unit 5 receives the digital audio signal obtained by the demodulator of the loudspeaker slave station 3, it activates the audio adjustment circuit 7. The audio adjustment circuit 7 has, for example, a filtering function for removing noise components, an equalizer function for adjusting frequency characteristics, and a function for adjusting the volume and sound speed, and performs audio adjustment on the digital audio signal so that the voice of the disaster prevention administrative radio is easy to hear. Specific examples of such audio adjustment include adjusting the playback speed of the digital audio signal to 300 characters / minute and adjusting the frequency of the digital audio signal to 2 kHz to 8 kHz. Then, the digital audio signal after the audio adjustment is transmitted to the information storage unit 6.

[0028] When the information storage unit 6 receives the audio-adjusted digital audio signal from the audio adjustment circuit 7 of the control unit 5, it stores it. Then, when it receives an output instruction from the control unit 5, it outputs the stored digital audio signal to the decoder. The output instruction may be output a predetermined time after the digital audio signal is received from the loudspeaker slave station 3, or may be output when the data amount of the digital audio signal stored in the information storage unit 5 reaches or exceeds a predetermined amount. The output instruction may also include the number of times the digital audio signal is to be repeatedly output, the time (e.g., an instruction as to what time the output is to be continued), the output interval, etc.

[0029] The FM transmitter 4 used in this embodiment may further include a parameter storage unit (parameter storage means) 8. Here, the "parameters" in the parameter storage unit 8 include parameters related to audio adjustment in the audio adjustment circuit 7 (e.g., frequency, volume, playback speed, etc.) and parameters related to the output timing of the digital audio signal included in the output instruction from the control unit 5. The parameter storage unit 8 stores these "parameters" and provides information about these "parameters" to the control unit 5 in response to an instruction from the control unit 5.

[0030] Next, the operation of the FM transmitter 4 according to the second embodiment will be described according to the flowchart shown in FIG. 4-2. Steps Sa1 and Sa2 in the flowchart shown in FIG. 4-2 are the same as those in the first embodiment, and therefore will not be described. When the FM transmitter 4 is started in response to a start signal from the loudspeaker slave station 3, the control unit 5 starts the audio adjustment circuit 7 (step Sb1). The audio adjustment circuit 7 adjusts physical properties such as the frequency, volume, and playback speed of the digital audio signal. Specifically, the playback speed of the digital audio signal can be adjusted to 300 characters / minute, and the frequency of the digital audio signal can be adjusted to 2 kHz to 8 kHz. Next, the digital audio signal after adjustment by the audio adjustment circuit 7 is transmitted to the information storage unit 6 and stored therein (step Sb2). The stored digital audio signal after audio adjustment is output to the D / A converter in response to an output instruction from the control unit 5 (step Sb3).

[0031] As explained above, according to the FM disaster prevention administrative radio transmission system 1 of this embodiment, the FM transmitter 4 stores and transmits digital audio signals, so the number of FM broadcasts, transmission timing, etc. can be easily adjusted, and it becomes possible to increase the opportunities for people who miss real-time FM broadcasts to receive disaster prevention administrative radio broadcasts later. Also, since the audio is adjusted by the audio adjustment circuit to have the desired physical properties such as frequency, volume, playback speed, etc., and then stored, it becomes possible to transmit disaster prevention administrative radio broadcasts that have been adjusted to be easy to hear.

[0032] In addition, parameters related to audio adjustment when adjusting the audio of a digital audio signal and parameters related to the output of a digital audio signal from the information storage unit 6 are stored in the parameter memory unit 8, making it easy to control audio adjustment, the transmission timing of FM broadcasts, etc.

[0033] (Embodiment 3) FIG. 3 is a schematic diagram showing the configuration of an FM disaster prevention administrative radio transmission system 1 in accordance with embodiment 3 of the present invention.

[0034] In the above-mentioned first and second embodiments, the FM transmitter 4 is activated in response to an activation signal output by the audio amplifier of the loudspeaker slave station 3 to activate the speaker, but there are also loudspeaker slave stations 3 that do not have a function for outputting an activation signal (in other words, a function for coordinating the FM transmitter 4). The FM transmitter 4 of the first and second embodiments cannot be applied to such loudspeaker slave stations 3.

[0035] The FM disaster prevention administrative radio transmission system 1 according to this embodiment solves the above problems. The FM disaster prevention administrative radio transmission system 1 according to this embodiment differs in configuration from that of the second embodiment in that the FM transmitter 4 includes a silence detector 9, but other configurations are the same as those of the second embodiment, so that the same reference numerals are used to designate the same configuration as the second embodiment and description thereof will be omitted.

[0036] This embodiment is characterized in that the FM transmitter 4 is provided with a silence detection section (silence detection means) 9 instead of being activated in response to an activation signal from the loudspeaker slave station 3.

[0037] The silence detector 9 is provided in the FM transmitter 4, and is constantly powered and operates even when the FM transmitter 4 is not activated, to detect the presence or absence of an input of a digital audio signal from the loudspeaker slave station 3. When the FM transmitter 4 detects the input of a digital audio signal from the loudspeaker slave station 3, the silence detector 9 activates the FM transmitter 4 and outputs the presence or absence of an input of a digital audio signal to the control unit 5. When a digital audio signal is input from the loudspeaker slave station 3, the control unit 5 causes each unit to execute a series of operations related to the storage and FM transmission of the digital audio signal (specifically, sound adjustment of the digital audio signal, storage and FM transmission of the digital audio signal, etc.). On the other hand, when the silence detector 9 does not detect a digital audio input for a predetermined time (this state is called "silence detection"), the control unit 5 transmits a signal to the sound adjustment circuit 7 to stop sound adjustment of the digital audio signal (sound adjustment stop signal) and transmits a signal to the information storage unit 6 to stop output of the digital audio signal (output stop signal). Then, the FM transmitter 4 is stopped. In this case, the predetermined time may be set appropriately.

[0038] Next, the operation of the FM transmitter 4 according to the above-mentioned embodiment 3 will be described with reference to the flowcharts shown in Fig. 5-1 and Fig. 5-2. Note that steps Sa1 and Sa2 and steps Sb1 to Sb3 in the flowchart shown in Fig. 5-1 are the same as those in the above-mentioned embodiments 1 and 2, and therefore the description thereof will be omitted.

[0039] When the silence detector 9 detects the input of a digital audio signal from the loudspeaker slave station 3, it starts the FM transmitter 4 and outputs the presence or absence of the input of a digital audio signal to the controller 5 (step Sc1). On the other hand, when the input of a digital audio signal is not detected for a predetermined time, the silence detector 9 judges this state as "silence detection" (step Sd1). Then, the controller 5 transmits a signal (audio adjustment stop signal) to the audio adjustment circuit 7 to stop the audio adjustment of the digital audio signal (step Sd2). Next, the controller 5 transmits an output stop signal to the information storage unit 6 to stop the output when the number of times of output of the digital audio signal set in the output instruction is reached (step Sd3). When the information storage unit 6 transmits the digital audio signal the number of times instructed by the output stop signal, it stops the transmission (step Sd4).

[0040] As described above, according to the FM disaster prevention administrative radio transmission system 1 of this embodiment, even if the loudspeaker substation 3 does not have the functionality for linking with the FM transmitter 4, it is possible to control the accumulation of digital audio signals and the start or stop of a series of operations related to FM transmission.

[0041] Although the embodiment of the present invention has been described above, the specific configuration is not limited to the above embodiment, and even if there are design changes within the scope of the present invention that do not deviate from the gist of the present invention, they are included in the present invention. [Explanation of symbols]

[0042] 1. FM Disaster Prevention Administrative Radio Transmission System 2 Master station 3. Public address station 4 FM transmitter 5 Control section (control means) 6 Information storage unit (information storage means) 7 Audio adjustment circuit 8 Parameter storage unit (parameter storage means) 9. Silence detection unit (silence detection means) 101 FM Disaster Prevention Administrative Radio Transmission System 102 Master station 103 Public address station 104 FM transmitter

Claims

1. An FM disaster prevention administrative radio transmission system comprising: a loudspeaker slave station that demodulates a disaster prevention administrative radio signal received from a master station into a digital audio signal, converts the digital audio signal into an analog audio signal, and outputs the analog audio signal by a speaker; and an FM transmitter connected to the loudspeaker slave station, The FM transmitter includes: receiving the digital audio signal from the loudspeaker slave station, converting the digital audio signal into an analog audio signal, and transmitting an FM signal obtained by FM modulating the analog audio signal via an antenna; FM disaster prevention administrative radio transmission system.

2. The FM transmitter comprises a control means, an audio adjustment circuit, and an information storage means; the control means adjusts the digital audio signal received from the loudspeaker slave station in the audio adjustment circuit, and transmits the adjusted digital audio signal to the information storage means; the information storage means stores the digital audio signal after audio adjustment, and outputs the digital audio signal for conversion into the analog audio signal in response to an output instruction from the control means; 2. An FM disaster prevention administrative radio transmission system according to claim 1.

3. The FM transmitter comprises a parameter storage means, the parameter storage means stores parameters relating to the audio adjustment in the audio adjustment circuit and parameters relating to the output of the digital audio signal included in the output instruction; 3. An FM disaster prevention administrative radio transmission system according to claim 2.

4. the FM transmitter includes a silence detection means for detecting the presence or absence of an input of the digital audio signal from the loudspeaker slave station, the silence detection means activates the FM transmitter when it detects the input of the digital audio signal.

4. An FM disaster prevention administrative radio transmission system according to claim 1, wherein the FM disaster prevention administrative radio transmission system is a radio wave transmitting system.

5. An FM disaster prevention administrative radio transmission method executed by an FM disaster prevention administrative radio transmission system including a loudspeaker slave station that demodulates a disaster prevention administrative radio signal received from a master station into a digital audio signal, converts the digital audio signal into an analog audio signal, and outputs the analog audio signal by a speaker, and an FM transmitter connected to the loudspeaker slave station, The FM transmitter includes: receiving the digital audio signal from the loudspeaker terminal and converting the digital audio signal into an analog audio signal; and transmitting an FM signal obtained by FM-modulating the analog audio signal by an antenna. FM disaster prevention administrative radio transmission method.

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