JP5154504B2 - Disaster prevention receiver - Google Patents

Description

  The present invention relates to a disaster prevention receiver capable of receiving a disaster prevention radio broadcast and an earthquake early warning.

For example, in an area such as a municipality, when a disaster such as an earthquake, a fire, or a flood occurs, an emergency call to that effect is made using a disaster prevention radio broadcast. Such disaster prevention radio broadcasting often broadcasts information related to general administrative work.
In addition, disaster prevention radio broadcasting refers to radio in which administrative agencies such as municipalities notify the residents who live in the area of the administrative agency of the above-mentioned emergency notification, information on general administrative work, and the like.

In an emergency, various information is transmitted from the master station, and the outdoor loudspeaker receiving device arranged in the area loudspeaks the received information through a speaker and notifies the residents in the area where the outdoor loudspeaker receiving device is installed.
Various information transmitted from the master station can also be received by a receiver or the like, and emergency information is notified to the residents of each household through the receiver.

  For example, the disaster prevention radio broadcast receiver disclosed in Patent Document 1 can receive AM / FM broadcast in addition to the disaster prevention radio broadcast. This receiver is equipped with a function to automatically receive a disaster prevention radio broadcast when the disaster prevention radio broadcast is broadcast, even when the power is off, and automatically listen to the disaster prevention radio broadcast. ing.

By the way, in recent years, an earthquake early warning is reported several tens of seconds before the S-wave (transverse wave) that causes a large tremor is captured and captured in the epicenter immediately after the earthquake occurs, tens of seconds before it reaches the residential area. Can be notified.
The earthquake early warning is, for example, information on the epicenter, the time of occurrence of the earthquake, the area to be alerted, the predicted seismic intensity, and the magnitude, and is published by the Japan Meteorological Agency.

For example, the Japan Broadcasting Corporation (hereinafter abbreviated as NHK), when an earthquake occurs, broadcasts an earthquake early warning published by the Japan Meteorological Agency via television broadcasting and radio broadcasting (for example, FM broadcasting) (non-patent literature). 1).
In television broadcasting, after the chime sound that notifies the start of the earthquake early warning is sounded, the earthquake early warning using characters and figures is displayed on the screen of the television receiver.
On the other hand, in radio broadcasting, programs such as news and music are interrupted, the chime sound is sounded, and then an earthquake early warning having the same content as that of television broadcasting is promptly delivered by voice.

  For example, the earthquake early warning terminal disclosed in Patent Document 2 can detect the emergency earthquake bulletin mentioned above and notify it.

In addition, commercial broadcasting stations have started operation of earthquake early warning as well as NHK. However, depending on the broadcasting station, the chime sound and its name may differ from those of NHK.
The Fire and Disaster Management Agency has also begun operating emergency earthquake warnings using disaster-prevention radio broadcasting using the Japan Instant Warning System (J-ALERT).

JP 2007-43641 A JP 2006-145234 A

NHK, "Earthquake Early Warning" to be notified before shaking, [online], [Search April 13, 2009], <URL: http://www.nhk.or.jp/bousai/index.html>

  The disaster prevention radio broadcast receiver disclosed in Patent Document 1 is equipped with means capable of receiving AM / FM broadcasts and disaster prevention radio broadcasts. Even if the power is off, the receiver automatically No means is provided for receiving AM / FM broadcasts and listening for emergency earthquake warnings of AM / FM broadcasts.

  The earthquake early warning terminal disclosed in Patent Document 2 is equipped with means capable of receiving AM / FM broadcasts, but is not equipped with means capable of listening to disaster prevention radio broadcasts. Furthermore, the use purpose of this earthquake early warning terminal is limited to the acquisition of the earthquake early warning.

As mentioned above, some government agencies such as municipalities provide emergency earthquake warnings using a nationwide instantaneous warning system, but this system has not been introduced to all government agencies, and disaster prevention radio broadcasts are received. Possible areas are limited.
In addition, as of 2009, this nationwide instantaneous warning system is under development, and the earthquake early warning based on this system may be delayed from the one based on AM / FM broadcasting.

  From this point of view as well, the early warning from the radio broadcast station has more advantages with respect to the early earthquake warning, and even when the power is off, the emergency earthquake warning of AM / FM broadcasting can be received automatically. Development of the machine is desired.

  An object of the present invention is to provide a disaster prevention receiver that can receive disaster prevention radio broadcasts and AM / FM broadcasts and can automatically listen to emergency earthquake warnings of AM / FM broadcasts even when the power is off. .

A disaster prevention receiver according to the present invention includes a reception unit that receives a disaster prevention radio signal and a broadcast signal, and a broadcast signal having a predetermined frequency selected in advance from frequency components included in the broadcast signal received by the reception unit. Based on the broadcast signal of the predetermined frequency extracted by the extraction unit, a detection unit that detects a notification voice signal for reporting the start of emergency bulletin, and outputs a detection signal; When the disaster prevention radio signal and the broadcast signal are output as an audio signal, and the detection signal output by the detection unit is received and the output unit is in a non-output state , and at least start portion for the broadcasting signal is activated the output unit to output a state capable as the audio signal, the detection unit, the waveform of the broadcast signal of the predetermined frequency, the upper Symbol broadcast audio signal waveform In The determination criterion includes a first determination criterion relating to a broadcast signal level of the predetermined frequency and a second determination criterion regarding a period of the broadcast signal of the predetermined frequency, and The signal level and the period are respectively compared with the first determination criterion and the second determination criterion, and the broadcast signal level and the period are compared with the first determination criterion and the second determination criterion. When each is satisfied, it is determined that the broadcast signal is the notification audio signal, and the detection signal is output.

  Preferably, the determination criterion includes a first determination criterion relating to a broadcast signal level of the predetermined frequency, a first peak value of the broadcast signal of the predetermined frequency, and a second continuous with the first peak value. A second determination criterion relating to a time width with respect to a peak value, wherein the detection unit is configured to output the broadcast signal level, the first peak value, the second peak value, and the time at the predetermined frequency. An acquisition unit that acquires a width, and the first peak value acquired by the acquisition unit is compared with a first threshold value of the first determination criterion, and after a predetermined time has elapsed from the first peak value A comparison unit that compares the broadcast signal level with a second threshold value of the first determination criterion and compares a difference between the time width and the time width of the second determination criterion with an allowable value; As a result of comparison by the comparison unit, the first peak value is greater than or equal to the first threshold value. And determining that the broadcast signal is the notification audio signal when the broadcast signal level after the lapse of the predetermined time is equal to or less than the second threshold value and the difference is equal to or less than the allowable value. Part.

  Preferably, the disaster prevention receiver includes a storage unit that stores the broadcast signal, and the output unit stores the notification signal stored in the storage unit when the notification audio signal is detected by the detection unit. The broadcast signal is output as the audio signal.

  ADVANTAGE OF THE INVENTION According to this invention, even if a disaster prevention radio broadcast and AM / FM broadcast can be received and a power supply is OFF, the emergency earthquake early warning of AM / FM broadcast can be heard automatically.

FIG. 1 is a diagram for explaining an overview of a disaster prevention receiver according to the first embodiment of the present invention. FIG. 2 is a block diagram illustrating a configuration example of a main part of the disaster prevention receiver according to the first embodiment of the present invention. FIG. 3 is a diagram illustrating an example of a chime sound waveform. FIG. 4 is a diagram illustrating an example of a spectrum component of a chime sound. FIG. 5 is a diagram illustrating an output example of the filter according to the first embodiment of the present invention. FIG. 6 is a block diagram showing a configuration example of the microcomputer according to the first embodiment of the present invention. FIG. 7 is a diagram illustrating an output example of the digital filter according to the first embodiment of the present invention. FIG. 8 is a diagram for explaining the determination criterion according to the first embodiment of the present invention. FIG. 9 is a flowchart showing an operation example of the disaster prevention receiver according to the first embodiment of the present invention. FIG. 10 is a block diagram illustrating a configuration example of a disaster prevention receiver according to the second embodiment of the present invention.

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

(First embodiment)
[Outline of disaster prevention receiver]
An outline of the disaster prevention receiver according to the present embodiment will be described with reference to FIG.
FIG. 1 is a diagram for explaining an overview of a disaster prevention receiver according to the first embodiment of the present invention.

As illustrated in FIG. 1, the disaster prevention receiver 10 is provided in each home 21. Of course, each individual may own it.
As a feature of the present embodiment, the disaster prevention receiver 10 has a function of receiving an AM / FM broadcast transmitted by the radio broadcast station 22 (AM / FM reception mode) and a function of receiving a disaster prevention radio broadcast transmitted by the master station 23. (Disaster prevention radio reception mode).

Here, the correspondence between the components of the present invention and the components of the present embodiment will be described.
The broadcast signal of the present invention corresponds to an AM / FM signal. The emergency bulletin of the present invention corresponds to the emergency earthquake bulletin. The notification sound of the present invention corresponds to a chime sound.

For example, when an earthquake occurs during reception of AM / FM broadcast, if the disaster prevention receiver 10 is powered on (simply referred to as power on), the earthquake early warning transmitted by the radio broadcast station 22 is transmitted. Can be heard.
However, if a general radio receiver is turned off, the earthquake early warning cannot be heard until the power is manually turned on.
Therefore, even when the power is off, the disaster prevention receiver 10 automatically activates the audio output system and listens to the emergency earthquake bulletin when the emergency earthquake bulletin by the radio broadcast station 22 is broadcast. It has a standby mode that can do.

  In addition, when the disaster prevention receiver 10 receives a disaster prevention radio broadcast using a squelch function, which will be described later, even if the power is off, the audio output system is automatically activated and the disaster prevention radio broadcast is performed. It has a squelch mode that can be heard.

As described above, since the disaster prevention receiver 10 is equipped with the standby mode and the squelch mode, even when the power is off, the emergency earthquake warning and the disaster prevention radio broadcast can be heard without missing.
The earthquake early warning is broadcasted by the radio broadcasting station 22, and the disaster prevention radio broadcasting is broadcasted by the master station 23. Although their broadcasting systems are different from each other, both broadcasts are performed simultaneously. There is.
For such a case, it is desirable to select in advance which of the standby mode and the squelch mode is to be executed with priority.
For example, this selection may be performed by the user, or may be performed based on the signal received earlier among the AM / FM signal and the disaster prevention radio signal.
In the following description, in this case, it is assumed that the standby mode has priority over the squelch mode.

  The radio broadcasting station 22 transmits programs such as news and music by AM / FM waves. When an earthquake occurs, this radio broadcast station 22 interrupts the program being broadcast and plays a chime sound. Then, for example, “Earthquake early warning. I do.

  The chime sound is for notifying the start of emergency earthquake warning. As described above, the chime sound may have a different name or melody for each radio broadcast station. In the present embodiment, the chime sound employed by NHK will be described as an example.

  The master station 23 constitutes a part of the disaster prevention administrative radio system. The master station 23 is installed, for example, at a municipal office, and transmits an emergency broadcast using a disaster prevention radio signal when a disaster occurs. At this time, the outdoor loudspeaker receiving device 24 installed for each region of the municipality receives the disaster prevention radio signal and outputs the emergency broadcast by voice.

  Depending on the master station 23 in the residential area, emergency earthquake warning using disaster prevention radio broadcasting is performed in the same manner as the radio broadcasting station 22, but in this embodiment, only the radio broadcasting station 22 is used for clarity of explanation. Earthquake early warning shall be performed.

In addition, the master station 23 transmits, for example, information related to administrative work by a disaster prevention radio signal at a predetermined time such as morning and evening.
The disaster prevention radio signal transmitted by the master station 23 is, for example, an FM wave in an extremely narrow frequency band. The frequency band is, for example, 68 MHz to 70 MHz, and is a frequency band in the vicinity of a part of the frequency band of FM broadcasting.

[Configuration example of disaster prevention receiver 10]
Next, a configuration example of the disaster prevention receiver 10 will be described with reference to FIG.
FIG. 2 is a block diagram illustrating a configuration example of a main part of the disaster prevention receiver according to the first embodiment of the present invention.

  As shown in FIG. 2, the disaster prevention receiver 10 includes an antenna 11, an AM / FM reception circuit 12, a disaster prevention radio reception circuit 13, a filter 14, a microcomputer 15, a changeover switch 16, and an output amplifier (amplification circuit) control circuit 17. And an output amplifier 18 and a speaker 19.

Here, the correspondence between the components of the present invention and the components of the present embodiment will be described.
The receiving unit of the present invention corresponds to the AM / FM receiving circuit 12 and the disaster prevention radio receiving circuit 13.
The extraction unit of the present invention corresponds to the filter 14.
The detection unit of the present invention corresponds to the microcomputer 15.
The starting unit of the present invention corresponds to the output amplifier control circuit 17.
The output unit of the present invention corresponds to the output amplifier 18 and the speaker 19.

The antenna 11 not only receives AM / FM broadcast from the radio broadcast station 22, but also receives disaster prevention radio broadcast from the master station 23.
As described above, since the disaster prevention radio signal is a signal in the frequency band of the FM wave, the antenna 11 is shared by the AM / FM reception circuit 12 and the disaster prevention radio reception circuit 13.

The AM / FM receiving circuit 12 is, for example, a so-called PLL (Phase-locked loop) type receiving circuit capable of receiving AM / FM broadcasting.
The AM / FM receiving circuit 12 tunes to the frequency designated by the user in accordance with the control signal S5 input from the microcomputer 15.

  However, when the power is off, the AM / FM receiver circuit 12 tunes to the broadcast frequency of the radio broadcast station 22 where the chime sound is broadcast. In the present embodiment, this broadcast frequency is, for example, a frequency at which NHK radio broadcast can be received.

  When a high frequency AM / FM signal is input from the antenna 11, the AM / FM reception circuit 12 demodulates the AM / FM signal, and outputs the demodulated low frequency AM / FM signal S1 to the filter 14 and the changeover switch 16, respectively. To do.

The disaster prevention radio reception circuit 13 includes a squelch circuit 131. The disaster prevention radio reception circuit 13 is set to be able to receive only FM waves in the frequency band of the disaster prevention radio signal from the master station 23, for example.
When a high-frequency disaster prevention radio signal is input from the antenna 11, the disaster prevention radio reception circuit 13 demodulates this and outputs the demodulated low-frequency disaster prevention radio signal S <b> 2 to the changeover switch 16.

  Note that power is supplied to the AM / FM receiver circuit 12, the disaster prevention radio receiver circuit 13, the microcomputer 15, and the output amplifier control circuit 17 even when the power is off.

  In order to execute the squelch mode, the squelch circuit 131 determines whether or not a disaster prevention radio signal has been received based on the FM wave. In this determination, the squelch circuit 131 compares whether the magnitude of noise included in the output signal of the disaster prevention radio reception circuit 13 is larger or smaller than a preset value.

In addition, squelch is a disaster prevention through the speaker 19 by detecting the difference in S / N ratio at the time of tuning and at the time of non-tuning in order to reduce or reduce the noise generated between stations in the FM receiver in the FM receiver. A function that turns on or off the output of a radio signal.
Specifically, when the SN ratio is smaller than the specified value, the output of the disaster prevention radio signal is turned off as having a lot of noise, and when the SN ratio is larger than the specified value, the disaster prevention radio through the speaker 19 is assumed as having less noise. The signal output is turned on.

When the noise is larger, the squelch circuit 131 recognizes that the disaster prevention radio signal is not received (not detected).
On the other hand, when the noise is smaller, the squelch circuit 131 recognizes that the disaster prevention radio signal has been received (detected). Then, the squelch circuit 131 outputs a squelch signal S3 to the microcomputer 15.
This squelch signal S3 is a signal for switching the output of the changeover switch 16 to the disaster prevention radio signal S2.

  In the squelch mode, when the power is off, when the disaster prevention radio signal is detected by the squelch circuit 131, the output amplifier 18 is activated by the output amplifier control circuit 17, and the disaster prevention radio signal S2 amplified by the output amplifier 18 is an audio signal. It is output through the speaker 19 as S8.

  The filter 14 is composed of a bandpass filter that passes only a signal having a predetermined frequency. When the AM / FM signal S <b> 1 is input from the AM / FM receiving circuit 12, the filter 14 extracts an AM / FM signal S <b> 14 having a predetermined frequency component from this signal and outputs it to the microcomputer 15.

Although details will be described later, the filter 14 is provided to facilitate detection of a chime sound performed by the microcomputer 15.
The extraction frequency of the filter 14 can be suitably selected from the frequencies included in the chime sound. In the present embodiment, the extraction frequency is set to a frequency when the chime sound has the maximum amplitude, for example, 659 Hz.

As described above, since the emergency earthquake bulletin is broadcast after the chime sound, if the chime sound can be detected, it can be understood that the emergency earthquake bulletin is broadcast thereafter.
Therefore, when the AM / FM signal S14 is input from the filter 14, the microcomputer 15 detects a chime sound in real time based on the AM / FM signal S14 (detection process).
When the microcomputer 15 detects a chime sound, it outputs a detection signal S4 indicating that to the output amplifier control circuit 17.

Further, even when the squelch signal S3 is input from the squelch circuit 131, the microcomputer 15 outputs a detection signal S4 indicating that to the output amplifier control circuit 17.
The microcomputer 15 outputs a control signal S5 for controlling the reception frequency of the AM / FM receiving circuit 12 to the AM / FM receiving circuit 12.

In addition, the microcomputer 15 outputs to the changeover switch 16 a switch control signal S6 for changing the output of the changeover switch 16 to the AM / FM signal S1 or the disaster prevention radio signal S2.
For example, when detecting a chime sound, the microcomputer 15 outputs a switch control signal S6 and switches the output of the changeover switch 16 to the AM / FM signal S1.
On the other hand, when the disaster prevention radio signal is detected by the squelch circuit 131 and the squelch signal S3 is input, the microcomputer 15 outputs the switch control signal S6 and switches the output of the changeover switch 16 to the disaster prevention radio signal S2.

The AM / FM signal S <b> 1 is input from the AM / FM receiver circuit 12 and the disaster prevention radio signal S <b> 2 is input from the disaster prevention radio reception circuit 13 to the changeover switch 16.
The changeover switch 16 outputs the AM / FM signal S1 or the disaster prevention radio signal S2 to the output amplifier 18 based on the switch control signal S6 input from the microcomputer 15.

Specifically, when a chime sound is detected in the standby mode, the changeover switch 16 outputs the AM / FM signal S1 to the output amplifier 18.
On the other hand, when the disaster prevention radio signal is detected in the squelch mode, the changeover switch 16 outputs the disaster prevention radio signal S2 to the output amplifier 18.

Basically, the changeover switch 16 switches the output based on the switch control signal S6. However, the output may be manually switched regardless of the switch control signal S6.
For example, when the power is on and the AM / FM reception mode is selected by the user, the AM / FM signal S1 is output to the changeover switch 16, and when the disaster prevention radio reception mode is selected, the switching is performed. The switch 16 can output the disaster prevention radio signal S2.

The output amplifier control circuit 17 has a function of controlling the output amplifier 18 to be on (energized state) or off (non-energized state).
When the output amplifier 18 is off, when the detection signal S4 is input from the microcomputer 15, the output amplifier control circuit 17 outputs the start signal S7 to the output amplifier 18, and switches the output amplifier 18 from off to on. Let
Conversely, when the output amplifier 18 is on, the output amplifier control circuit 17 can also switch the output amplifier 18 from on to off in accordance with an instruction from the microcomputer 15.

  The output amplifier 18 is composed of, for example, a low frequency amplifier circuit having a sound frequency band characteristic. The output amplifier 18 amplifies the AM / FM signal S1 or the disaster prevention radio signal S2 input from the changeover switch 16, and outputs the amplified signal to the speaker 19 as an audio signal S8.

The output amplifier 18 is activated when the activation signal S7 is input from the output amplifier control circuit 17 when the power supply of the disaster prevention receiver 10 is off.
In this case, the output amplifier 18 amplifies the sound level (volume) of the signal input from the changeover switch 16 to about half of the maximum sound level, regardless of the preset output sound level.

  The speaker 19 outputs an audio signal S8 having an audio level adjusted by the output amplifier 18.

[Overview of detection processing]
Hereinafter, chime sound detection processing in the standby mode will be described.
First, the chime sound will be described with reference to FIG.
FIG. 3 is a diagram illustrating an example of a chime sound waveform. In FIG. 3, the horizontal axis represents time, and the vertical axis represents chime sound amplitude (for example, voltage).

As shown in FIG. 3, the chime sounds are substantially the same after the announcement that the main broadcast is an emergency earthquake bulletin is made after approximately the same sounds a and b are repeated twice in about 1500 ms. Sounds c and d are repeated twice at approximately 1500 ms. However, only the waveform of the chime sound is shown in FIG.
In the following description, the sounds a to d are also referred to as a first chime sound a, a second chime sound b, a third chime sound c, and a fourth chime sound d.
After the fourth chime sound d ends, an emergency earthquake warning is performed.

  If it is an earthquake early warning, the chime sound for emergency earthquake early warning is used. Therefore, if the AM / FM signal S1 received by the AM / FM receiving circuit 12 matches the waveform of the chime sound, it can be determined that the AM / FM signal S1 is a chime sound signal. .

  However, in reality, it is extremely rare that the signal waveforms of the two coincide completely, and if both signal waveforms themselves are compared in real time, a huge amount of signal processing is required. .

  Therefore, in the present embodiment, attention is paid to a predetermined frequency among the frequencies included in the first to fourth chime sounds a to d, and the waveform of the AM / FM signal S1 at this frequency matches the waveform of the chime sound. It is determined whether or not.

  The first and second chime sounds a and b are repeated twice at approximately 1500 ms, and the third and fourth chime sounds c and d are transmitted twice at approximately 1500 ms after the broadcast indicating that the main broadcast is an emergency earthquake warning. Again, since each sound is substantially the same, it is not necessary to detect all the chime sounds. If all the chime sounds are to be detected, the process takes time, and until the second chime sound b is detected, the process is performed after the end of the chime sound and before the start of the third chime sound c. Cannot be output through the speaker 19.

From the above viewpoint, it is practically necessary and sufficient if the first first chime sound a can be detected.
Therefore, in the detection process, it is determined whether or not the waveform of the AM / FM signal S1 at the predetermined frequency is the waveform of the first chime sound a.
In this determination, it is determined whether or not the waveform of the AM / FM signal S1 satisfies the determination criterion, instead of directly comparing whether or not the two waveforms match. When the waveform satisfies the determination criterion, it is determined that the AM / FM signal S1 is a chime sound. This criterion will be described later.

  The predetermined frequency can be selected as follows. Here, an example of the spectrum component of the chime sound shown in FIG. 3 is shown in FIG. In FIG. 4, the horizontal axis indicates the frequency, and the vertical axis indicates the signal level (for example, voltage).

As shown in FIG. 4, the chime sound is composed of frequency components up to about 11 kHz. One frequency may be selected from these frequencies, but the frequency to be selected is preferably a frequency at which the chime sound waveform can be clearly grasped.
Note that this selection is not performed by the user, but is performed at the design stage of the disaster prevention receiver 10.

That is, it is desirable that the signal level shown in FIG. In the case of the spectrum illustrated in FIG. 4, the frequencies with relatively high signal levels compared to others are, for example, 391 Hz, 415 Hz, 523 Hz, 554 Hz, 654 Hz, 659 Hz, and 698 Hz. One frequency may be selected from these.
More preferably, the signal level having the largest amplitude is preferable so that the determination using the determination criterion is easy.
For this reason, in this embodiment, the frequency of 659 Hz with the largest amplitude of the signal level is selected. One frequency may be selected from the harmonics of the exemplified frequency.

FIG. 5 is a diagram illustrating an output example of the filter according to the first embodiment of the present invention. FIG. 5 illustrates first to third chime sounds a to c extracted by the filter 14.
In FIG. 5, the horizontal axis indicates time, and the vertical axis indicates the signal level. The symbols “a” to “c” correspond to the first to third chime sounds a to c, respectively.

As shown in FIG. 5, when an AM / FM signal S1 corresponding to a chime sound is input, the filter 14 extracts an AM / FM signal S14 having a 659 Hz component.
Actually, the filter 14 extracts an AM / FM signal S14 having a 659 Hz ± 30 Hz component.
The time width between the peak values is equal to the period of the chime sound shown in FIG. 3 and is about 1500 ms.

[Configuration Example of Microcomputer 15]
Next, a configuration example of the microcomputer 15 that performs the detection process will be described with reference to FIG.
FIG. 6 is a block diagram showing a configuration example of the microcomputer according to the first embodiment of the present invention.

  As illustrated in FIG. 6, the microcomputer 15 includes an A / D conversion unit 151, a digital filter 152, an acquisition unit 153, a comparison determination unit 154, a detection signal output unit 155, and a changeover switch control unit 156.

Here, the correspondence between the components of the present invention and the components of the present embodiment will be described.
The comparison unit and determination unit of the present invention correspond to the comparison determination unit 154.
The conversion unit of the present invention corresponds to the A / D conversion unit 151.
The second extraction unit of the present invention corresponds to the digital filter 152.
The first peak value of the present invention corresponds to the peak value P1, and the second peak value of the present invention corresponds to the peak value P2.
The first threshold value of the present invention corresponds to the threshold value Th1, and the second threshold value of the present invention corresponds to the threshold value Th2.

  When the AM / FM signal S14 having a frequency of 659 Hz ± 30 Hz is input from the filter 14, the A / D converter 151 converts the analog signal into a digital signal, and outputs the digital signal S151 to the digital filter 152.

By the way, the filter 14 is basically an analog filter. For this reason, the AM / FM signal S14 extracted by the filter 14 becomes a non-smooth signal as shown in FIG. 5 due to the analog characteristics of the filter 14 and the influence of noise.
Naturally, the digital signal S151 is also a non-smooth signal, similarly to the AM / FM signal S14, and there is a possibility that erroneous determination is caused by processing in the comparison determination unit 154 and the like described later.

Therefore, a digital filter 152 is provided to remove noise and the like included in the digital signal S151 and smooth the signal.
The digital filter 152 extracts a signal having the same frequency as the extraction frequency of the filter 14 from the digital signal S151 by digital processing, and outputs this to the acquisition unit 153 as the extraction signal S152.
In the present embodiment, the extraction frequency of the digital filter 152 is a 659 Hz ± 30 Hz component.

FIG. 7 is a diagram illustrating an output example of the digital filter according to the first embodiment of the present invention. FIG. 7 illustrates first to fourth chime sounds a to d extracted by the digital filter 152.
In FIG. 7, the horizontal axis indicates time, and the vertical axis indicates signal level. The symbols “a” to “d” correspond to the first to fourth chime sounds a to d.

As shown in FIG. 7, the first chime sound a macroscopically rises in signal level and attenuates monotonically from the peak value Pa. The same applies to the second to fourth chime sounds b to d.
As described above, the extracted signal S152 extracted by the digital filter 152 is a signal smoother than the AM / FM signal S14 extracted by the filter 14 from which noise and the like are removed.
For convenience of explanation, the peak value of the second chime sound b is Pb. The time width between the peak value Pa and the peak value Pb is ΔTab.

[Criteria]
When detecting the first chime sound a, it is determined whether or not the waveform of the extracted signal S152 satisfies the determination criterion. Here, this determination criterion will be described with reference to FIG.

  FIG. 8 is a diagram for explaining the determination criterion according to the first embodiment of the present invention. In FIG. 8, an example of the extraction signal S152 is schematically illustrated by a solid line, and the first and second chime sounds a and b are illustrated by a broken line.

As described above, the first chime sound a attenuates monotonically from the peak value Pa macroscopically.
Therefore, in order to determine that the extraction signal S152 is the first chime sound a, (a) the peak value P1 of the extraction signal S152 is larger than the threshold value Th1, and (b) the time when the peak value P1 is acquired. The signal level after the lapse of the predetermined time Δtp from the first threshold value should be smaller than the threshold Th2 (first determination criterion).
The predetermined time Δtp is, for example, about 375 ms (= 1500 ms / 4), and is a time when the attenuation of the extraction signal S152 becomes clear.

  However, a sufficient signal level cannot be obtained depending on the reception state of the AM / FM receiving circuit 12, and even if a chime sound is received, the first chime sound a can be obtained only by the first criterion. May not be detected.

For this reason, in the present embodiment, the time width ΔT between the peak value P1 and the peak value P2 in the extraction signal S152 and the time width ΔTab (approximately 1500 ms) in the first and second chime sounds a and b are approximately the same. A determination is made whether or not there is.
The time width ΔT can be acquired from the time when the peak values P1 and P2 are acquired. (C) The absolute value (| ΔT−ΔTab |) of the difference between the time width ΔT and the time width ΔTab may be equal to or smaller than the allowable value α (for example, α = 10 ms) (second determination criterion).
Thus, by providing the first and second determination criteria, a chime sound can be detected reliably and easily.

When the extraction signal S152 is input from the digital filter 152, the acquisition unit 153 acquires the signal level and peak values P1 and P2 of this signal. Then, the acquisition unit 153 acquires a time width ΔT between the two peak values from the time when the peak values P1 and P2 are acquired.
Thereafter, the acquisition unit 153 outputs the peak values P1 and P2 and the time width ΔT as an acquisition result S153 to the comparison determination unit 154. In addition, the acquisition unit 153 also outputs a signal level between the peak value P1 and the peak value P2 to the comparison determination unit 154.

  When the acquisition result S153 is input from the acquisition unit 153, the comparison determination unit 154 compares (a) the peak value P1 with the threshold value Th1 based on the first and second determination criteria, and (b) the peak value P1. The signal level (= L) after the lapse of the predetermined time Δtp from the time when the time is acquired is compared with the threshold Th2, and (c) the absolute value (= | ΔT−ΔTab |) of the difference between the time width ΔT and the time width ΔTab is obtained. Compare with tolerance α.

  The comparison determination unit 154 includes (a) the peak value P1 is equal to or greater than the threshold value Th1 (P1 ≧ Th1), (b) the signal level (= L) is equal to or less than the threshold value Th2 (L ≦ Th2), and (c) When the absolute value of the difference (| ΔT−ΔTab |) is equal to or smaller than the allowable value α (| ΔT−ΔTab | ≦ α), the extracted signal S152, that is, the received AM / FM signal S1 is a chime sound. Is determined.

When the extracted signal S152 is a chime sound, the comparison determination unit 154 outputs a determination result S154 to that effect to the detection signal output unit 155.
On the other hand, when the extracted signal S152 is not a chime sound, the comparison determination unit 154 outputs a determination result S154 to that effect to the detection signal output unit 155.

The detection signal output unit 155 outputs the detection signal S4 indicating that the chime sound is detected only when the determination result S154 indicating that the extraction signal S152 is a chime sound is input from the comparison determination unit 154. Output to.
At this time, the detection signal output unit 155 outputs a switching signal S155 for switching the output of the changeover switch 16 to the AM / FM signal S1 to the changeover switch control unit 156.

  After the processing of the detection signal output unit 155, the output amplifier 18 is activated by the output amplifier control circuit 17, and the AM / FM signal S1 is output through the speaker 19 as the audio signal S8.

  Thus, since the audio signal S8 is output when the first chime sound a is detected, the speaker 19 outputs the audio after the peak value P2 of the second chime sound b (FIG. 7).

When the switch signal S155 is input from the detection signal output unit 155, the switch controller 156 outputs the switch control signal S6 to the switch 16 and switches the output of the switch 16 to the AM / FM signal S1.
When the squelch signal S3 is input from the squelch circuit 131 in the squelch mode, the changeover switch control unit 156 outputs the switch control signal S6 to the changeover switch 16, and outputs the changeover switch 16 to the disaster prevention radio signal S2. Switch.

[Operation of disaster prevention receiver 10]
The operation of the disaster prevention receiver 10 will be described with reference to FIG. 9, focusing on the detection process in the standby mode.
FIG. 9 is a flowchart showing an operation example of the disaster prevention receiver according to the first embodiment of the present invention.

In the following description, first, it is assumed that the power supply of the disaster prevention receiver 10 is off. As shown in FIG. 9, since the AM / FM receiving circuit 12 is in an energized state, it can receive AM / FM broadcasts.
The AM / FM receiving circuit 12 demodulates the high frequency AM / FM signal input from the antenna 11, and outputs the demodulated low frequency AM / FM signal S1 to the filter 14 and the changeover switch 16 (step ST1). ).

  When the AM / FM signal S <b> 1 is input from the AM / FM receiving circuit 12, the filter 14 extracts an AM / FM signal S <b> 14 having a frequency of 659 Hz ± 30 Hz from this signal, and outputs the AM / FM signal S <b> 14 to the A / D converter 151. (Step ST2).

  The A / D converter 151 converts the AM / FM signal S14 having a frequency of 659 Hz ± 30 Hz into a digital signal, and outputs the digital signal S151 to the digital filter 152 (step ST3).

  Then, the digital filter 152 extracts a signal having a frequency of 659 Hz ± 30 Hz from the digital signal S151 by digital processing, and outputs this as an extraction signal S152 to the acquisition unit 153 (step ST4).

  Then, the acquisition unit 153 acquires the peak values P1 and P2 of the extraction signal S152 and the time width ΔT between the two peak values. Thereafter, the acquisition unit 153 outputs the peak values P1 and P2 and the time width ΔT as an acquisition result S153 to the comparison determination unit 154 (step ST5).

  Then, the comparison determination unit 154 determines whether or not the peak values P1, P2 and the time width ΔT satisfy the first and second determination criteria (step ST6).

  If the extracted signal S152 is a chime sound (YES in step ST6), the comparison / determination unit 154 outputs a determination result S154 to that effect to the detection signal output unit 155.

  The detection signal output unit 155 outputs the detection signal S4 indicating that the chime sound is detected only when the determination result S154 indicating that the extraction signal S152 is a chime sound is input from the comparison determination unit 154. Output to the circuit 17. (Step ST7).

Next, the output amplifier control circuit 17 receives this detection signal S4 and outputs a start signal S7 for starting the output amplifier 18 to the output amplifier 18.
Then, when activated, the output amplifier 18 amplifies the AM / FM signal S1 input from the changeover switch 16, and outputs the amplified signal to the speaker 19 as an audio signal S8.
Thereby, the sound from the middle of the second chime sound b is output through the speaker 19 (step ST8).

On the other hand, when the extracted signal S152 is not a chime sound (NO in step ST6), the comparison determination unit 154 outputs a determination result S154 to that effect to the detection signal output unit 155.
In this case, the detection signal output unit 155 does not output the detection signal S4 to the output amplifier control circuit 17, and the process of step ST1 is resumed.

As described above in detail, the disaster prevention receiver 10 can receive disaster prevention radio broadcasts and AM / FM broadcasts automatically, and automatically listen to emergency earthquake warnings by AM / FM broadcasts even when the power is off. Can be possible.
For this reason, the disaster prevention receiver 10 can be used nationwide, and this can be listened to more quickly than the emergency earthquake warning by disaster prevention radio broadcasting.

  The detection process can be basically realized by the filter 14 and the microcomputer 15. Therefore, even with a general receiver such as a radio or a disaster prevention radio receiver, it is possible to share many components to realize the detection process, thereby reducing the cost.

In particular, since microcomputers are likely to affect the receiving circuit with noise and the like, it is desirable to reduce the number of use as much as possible. Since general receivers distributed in the market in recent years are often equipped with a microcomputer, they can be shared and the reception performance is not sacrificed.
Of course, by sharing parts, circuit design is facilitated, and the housing can be downsized.

(Second Embodiment)
As described above, in the disaster prevention receiver according to the first embodiment, when the earthquake early warning is performed when the power is off, it is possible to listen to the broadcast from the middle of the chime sound.
Even if the chime sound cannot be heard, the disaster prevention receiver plays the minimum necessary role if it can hear the earthquake early warning itself.
However, since the chime sound notifies the start of the emergency earthquake warning, it is desirable that the chime sound can be heard from the start of the first chime sound a.

  Therefore, in the second embodiment, a disaster prevention receiver capable of listening from the start to the end of a chime sound will be described with reference to FIG. Only the points related to the detection process will be described below.

  FIG. 10 is a block diagram illustrating a configuration example of a disaster prevention receiver according to the second embodiment of the present invention.

As illustrated in FIG. 10, the storage unit 110 is inserted between the changeover switch 16 and the output amplifier 18 in the disaster prevention receiver 10 a.
The storage unit 110 is, for example, a FIFO (First In-First Out). Other configurations are the same as those shown in FIG.

When the AM / FM receiving circuit 12 receives AM / FM reception from the antenna 11, the microcomputer 15 performs detection processing in real time based on the AM / FM signal S14 extracted by the filter 14.
On the other hand, when the AM / FM signal S1 is input from the changeover switch 16, the storage unit 110 temporarily stores the AM / FM signal S1 until the storage unit control signal S9 is input from the microcomputer 15. That is, all the chime sounds such as the first chime sound a, the second chime sound b,... Are sequentially stored in the storage unit 110.

  When the microcomputer 15 detects the first chime sound a, the microcomputer 15 outputs the detection signal S4 to the output amplifier control circuit 17 and outputs the storage unit control signal S9 to the storage unit 110.

Thereby, even if the power supply of the disaster prevention receiver 10a is off, the output amplifier 18 is activated by the output amplifier control circuit 17. At this time, the AM / FM signal S1, that is, the first chime sound a, the second chime sound b,.
As a result, the sound from the beginning of the first chime sound a is output through the speaker 19.

  According to the second embodiment, in addition to the effects described in the first embodiment, it is possible to listen from the start to the end of the chime sound.

(Third embodiment)
In the detection process, the first chime sound a is detected, and two determination criteria are provided in order to increase the detection accuracy.
However, when a melody or the like similar to a chime sound flows in a program, there is a risk of erroneous detection of the chime sound.

Therefore, in the third embodiment, when an erroneous detection of a chime sound occurs, the sound level is lowered to the lowest sound level.
Specifically, the microcomputer 15 determines whether each of the first chime sound a and the second chime sound b satisfies the first and second determination criteria.
For example, when the second chime sound b does not satisfy two determination criteria, the microcomputer 15 instructs the output amplifier control circuit 17 so that the sound level output from the output amplifier 18 becomes the lowest. .

At this time, the sound level may be silenced, or the power may be turned off.
Instead of changing the voice level, for example, a voice message such as “The current chime sound is a false alarm” may be output.
A display device may be provided in the disaster prevention receiver 10 to display on the display device that a chime sound has been erroneously detected.

  According to the third embodiment, in addition to the effects described in the first and second embodiments, when an erroneous detection of a chime sound occurs, the fact is notified, so the user's anxiety due to the erroneous notification is reduced. Can be made.

In the present invention, the first to third embodiments described above can be combined.
In the first to third embodiments described above, the NHK chime sound is exemplified as the notification sound. However, even if the notification sound to be detected is different from the chime sound, a predetermined frequency is selected from the frequencies included in the sound. It is possible to select and apply the present invention.
The present invention can also be applied to notification sounds employed in countries other than Japan.

For example, in the emergency tsunami bulletin, the emergency tsunami bulletin flows after substantially the same notification sound is repeatedly generated at a constant period, as in the chime sound given as an example. The present invention can also be applied to such an emergency tsunami warning.
The present invention can also be applied to emergency earthquake warnings by disaster prevention radio broadcasting using a nationwide instantaneous warning system.

  DESCRIPTION OF SYMBOLS 10, 10a ... Disaster prevention receiver, 11 ... Antenna, 12 ... AM / FM reception circuit, 13 ... Disaster prevention radio reception circuit, 14 ... Filter, 15 ... Microcomputer, 16 ... Changeover switch, 17 ... Output amplifier control circuit, 18 ... Output amplifier, 19 ... speaker, 110 ... storage unit, 131 ... squelch circuit, 151 ... A / D conversion unit, 152 ... digital filter, 153 ... acquisition unit, 154 ... comparison determination unit, 155 ... detection signal output unit, 156 ... Changeover switch control unit, 21 ... home, 22 ... radio broadcast station, 23 ... master station, 24 ... outdoor loudspeaker receiver

Claims (3)

A receiver for receiving the disaster prevention radio signal and the broadcast signal;
An extraction unit for extracting a broadcast signal of a predetermined frequency selected in advance from frequency components included in the broadcast signal received by the reception unit;
Based on the broadcast signal of the predetermined frequency extracted by the extraction unit, a detection audio signal for informing the start of emergency bulletin, and a detection unit for outputting a detection signal;
An output unit that outputs one of the disaster prevention radio signal and the broadcast signal as an audio signal;
An activation unit that receives the detection signal output from the detection unit and activates the output unit in a state where at least the broadcast signal can be output as the audio signal when the output unit is in a non-output state. And
The detection unit is
Waveform of the broadcast signal of the predetermined frequency has a criterion indicating that the waveform of the upper Symbol broadcast audio signal, the criterion includes a first criterion relates to a broadcast signal level of the predetermined frequency, the predetermined A second criterion for the frequency of the broadcast signal of the frequency,
The broadcast signal level and the period are respectively compared with the first determination criterion and the second determination criterion, and the broadcast signal level and the period are compared with the first determination criterion and the second determination criterion. When each of the above is satisfied, the broadcast signal is determined to be the notification audio signal, and the detection signal is output. The above criteria are
A first criterion for the broadcast signal level of the predetermined frequency;
A second determination criterion relating to a time width between a first peak value of the broadcast signal of the predetermined frequency and a second peak value continuous with the first peak value;
The detection unit is
An acquisition unit for acquiring the broadcast signal level, the first peak value, the second peak value, and the time width at the predetermined frequency;
The first peak value acquired by the acquisition unit is compared with a first threshold value of the first determination criterion, and the broadcast signal level after a predetermined time has elapsed from the first peak value is set to the first value. A comparison unit that compares the difference between the time width of the determination criterion and the time width of the second determination criterion with an allowable value;
As a result of comparison by the comparison unit, the first peak value is not less than the first threshold, the broadcast signal level after the predetermined time has elapsed is not more than the second threshold, and the difference is not less than the first threshold. The disaster prevention receiver according to claim 1, further comprising: a determination unit that determines that the broadcast signal is the notification sound signal when the broadcast signal is equal to or less than an allowable value. A storage unit for storing the broadcast signal;
The output section
When the broadcast audio signal is detected by the detecting unit, disaster prevention receiver according to claim 1 or 2 outputs the broadcast signal stored in the storage unit as the audio signal.

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