JPS6288440A - Emergency alarm broadcast receiver - Google Patents

Abstract

PURPOSE:To prevent the malfunction of an emergency alarm broadcast receiver by mischief by providing a non-modulation detection circuit detecting a non- modulation period. CONSTITUTION:The non-modulation period of 1.5sec or over exists without fail just before the start signal or the end signal of an emergency alarm broadcast. Then a non-modulation detection circuit 16 detecting the non-modulation period is provided from the output of a tuning circuit 2 and a processing circuit 14 receives the output of a discrimination reference circuit 13 just after the detection circuit 16 receives the non-modulation signal for 1.5sec. Thus, since a normal broadcast is applied from a broadcast station at normal state, no non-modulation period is exists. Then even when the same signal as a prescribed code is inputted to the emergency alarm broadcast by the mischief, the receiver is not operated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field 1] The present invention relates to an emergency warning broadcast receiver that receives emergency warning signals from emergency warning broadcasts.

1 Background Technology 1 Currently, emergency warning broadcasts have been started on NHK for the purpose of conveying information to viewers about emergency disasters (particularly emergency commercial disasters that interrupt regular programs and send out broadcasters). There is. This emergency warning broadcast is an emergency warning (1
In this method, the emergency warning signal is superimposed on the broadcast radio waves by interrupting and inserting the audio signal of the broadcast program, and the emergency warning signal is a binary N signal using a frequency within the audible band. RZ (N on -Return to
7. The system is based on a digital code signal using frequency shift keying (hereinafter referred to as 1:) modulation using ero), and has a transmission rate of 64 bits per second.

Furthermore, for emergency warning signals, mark (1) is 102411z,
16 bits with space (()) as 640 flz) [
The basic unit (one word) is the code signal, and the code signal is different for each earthquake, typhoon, tsunami, etc., and is sent periodically to avoid reception failure due to equipment malfunction in emergencies. Tess) (No. 4) is transmitted. This emergency warning broadcast is received by T'M, AM Ranoo, or television. Types of emergency warning signals include start signal and end signal. There are three types of signals:
It is composed of Ir outer codes and H(t) codes, and is designed to increase reliability against various reception conditions and interference.

Here, the start signal and end signal will be briefly explained. As shown in FIG. 6, the start signal and the end signal have six words formed by alternately connecting one fixed code word and one variable code word to form one code block. Then, as shown in Figure @7, the start signal is made by concatenating at least two code blocks, placing a direct signal at the beginning, and adding @
It consists of a 1.5 second non-modulation period before the image signal.
be,.

Also, the end signals are No. (shown in the figure), U1. ’: Prefix 4
A period corresponding to 2 blocks consisting of 1 block of 4g signal with g signal added to the beginning and a non-modulation period is repeated with a period of 12,
Continuation of Ili results in configuration 12'.

A block diagram of the emergency warning broadcast receiver 64 which receives the above-mentioned emergency warning broadcast is shown in FIG. , - The emergency warning broadcast reception is composed of a receiver (fl antenna 1, tuning circuit 2, demodulation circuit 3, amplifier circuit 5, and speaker 6; L - normal reception FD
It consists of an emergency alarm 4 that detects the emergency alarm 4H from the output of the demodulation circuit 3, and a call detection circuit 4.
Ke detector ll? 14 detects the start signal of the emergency warning broadcast and the end signal 18 [7. When the start signal 4W is detected, the external amplifier circuit 5 is driven 1. 1 so that the sound is emitted from speaker 6 with
7. When the end signal is detected again, the operation of the amplifier circuit 5 is stopped 1.[, and placed in a standby state. In other words, the tuning circuit 2, demodulation circuit 3, and C! of this emergency warning broadcast receiver! emergency alert jr
The No. t detection circuit 4 is in a standby state where power is always supplied and is ready to receive emergency warning broadcasts at any time.

Furthermore, 1] The shell/body circuit configuration of the emergency warning signal detection circuit 4 will be explained with reference to FIG. This emergency warning signal detection circuit 4 includes a filter 7 that converts the output of the demodulation circuit 3 into a digital signal, a shift register 9 that temporarily stores 1-bit data that is the output of this filter 7, and a digital signal based on the data that is the output of the shift register 9. A processing circuit 14 that performs signal processing, a memory 15 that stores start signal and end signal patterns to identify whether the data read by the processing circuit 14 is a start signal or an end signal, and a shift register 9 described in -. a timing circuit 8 that issues a timing signal to control the capture of the output of the filter 7; a register 11 that stores data of a 1-bit sample; and a comparison circuit 10 that compares the outputs of the shift register 9 and register 11. , shift register 9 to comparator circuit 10
and a counter 12 that counts the output of the comparator circuit 10 when it is determined that the registers 11 and 11 match, and a counter 1
The determination reference circuit 13 controls the processing circuit 14 to read the data in the seat register 9 when the count value of 7 is equal to or greater than a predetermined value.

The operation of the above-mentioned emergency alert (f') call detection circuit 4 will be explained below. 9. This signal is taken in by the timing circuit 8.
The import timing is 1-5ec. Therefore, as mentioned above, the transmission speed of the control signal for emergency warning broadcasting is (14 bits/second, so 1 bit of data is sampled 16 times, and in order to capture 1 bit of data, register 7) 9 requires 16 bits. When a signal without a 1-bit error is received at the output of the shift register 9, the same output is output for only 16 sample periods. The data from 1 bit sample ago is stored in the 16-bit F register 11, and is outputted from the shift register 9 by the comparator circuit 10 and sent to the S mester 1.
1 and the counter 12 indicates that they match. In addition, the count value of the counter 12 of b is 1161 when the error-free signal of 1 bit is taken in, but considering that there may be an error due to some reason, the count value of the counter 12 is A determination reference circuit 13 is provided so that when the counted value exceeds a certain reference value, the processing circuit 14 takes in data from a shift register.

The processing circuit 14 that has taken in the data of the shift register 9 compares the sequentially read data with the start signal pattern and the end f signal pattern stored in the memory 15, and determines whether it is a start signal or an end signal (Ft number, but how about it? is what is identified.

However, in the circuit described in -1-, when a prank signal similar to the predetermined code is input, the emergency warning broadcast receiver responds and a sound other than the emergency warning broadcast is generated, causing confusion.
There was a risk of causing L. Furthermore, although a 16-bit shift register 9, a 16-bit register 11, and a 16-bit comparison circuit 10 are required, there is a problem in that the scale of the circuit increases. Therefore, emergency warning 4fi detection circuit 4
Although it is conceivable to implement this part with a microprocessor, there is a problem that a large RAM 1i area is required, which increases the size of the microprocessor and increases the cost.

[Objective of the Invention 1 The present invention has been made in view of the above-mentioned points, and its object is to provide an emergency warning broadcast receiver that prevents malfunction due to mischief.

1 Disclosure of the Invention 1 (Structure) The present invention provides an emergency warning broadcast receiver that receives emergency warning broadcasts including frequency shift keying signals of two frequencies, a tuning circuit that tunes broadcast radio waves, and an output from the tuning circuit. a demodulation circuit that demodulates the signal into the voice band, a non-modulation detection circuit that detects non-modulation using No. 1 of the tuning circuit, and an emergency warning signal consisting of the start signal No. 44 and the end signal from the outputs of the no-modulation detection circuit and the demodulation circuit. The system is equipped with an emergency alarm signal detection circuit for detecting an emergency alarm signal, and a control circuit that operates the device after the first start according to the output of the emergency alarm signal detection circuit and returns to the original state after the end (fi). 11. Discloses an emergency warning broadcast receiver that can prevent malfunctions.

(Example 1) Figure vJ1 shows an emergency warning signal detection circuit 4 according to an embodiment of the present invention.
As mentioned above, there is always a non-modulation period of 1.5 seconds immediately before the start signal or end signal of the emergency warning broadcast.
This system focuses on the fact that there is a period of 5 seconds or more, and includes a non-modulation detection circuit 16 that detects this non-modulation period from the output of the tuning circuit 2 of the conventional circuit described above. Note that the other circuits are the same as those of the conventional example, so explanations will be omitted.

The operation of this embodiment will be explained below. The above non-modulation detection circuit 1
6, the unmodulated signal is transmitted for a certain predetermined time, in this example, 1.5
The processing circuit 14 processes the output of the judgment standard circuit 13 only immediately after receiving the seconds.
I will accept the reception.

Here, in normal times, there is no non-modulation period because the broadcast station is broadcasting normally.

Therefore, even if a signal identical to the predetermined code is input to the emergency warning broadcast receiver due to a prank or the like, the emergency warning broadcast receiver will not operate due to this prank signal and will not be able to receive the emergency warning broadcast. The aircraft receives only the official start signal and end signal 4g.

(Embodiment 2) FIG. 2 shows an emergency warning signal detection circuit 4 according to another embodiment of the present invention.
In this embodiment, the operation of the timing circuit 8 is controlled by the non-modulation detection circuit 161:, and the output of the timing circuit E1 is determined by the output of the non-modulation detection circuit 16 as shown in 1, :. By controlling the operation, the output of the filter 7 can be counted by the counter 12 in contact with the IM, which simplifies the circuit configuration. Specifically, there is a timing circuit 8 that operates on the output immediately after the non-modulation detection circuit 16 detects no modulation, a counter 12 that inputs the output of the filter 7 when the timing circuit 8 operates, and a counter 12 that receives the output of the counter 12. In addition, a control circuit 17 is newly provided which stops the operation of the timing circuit 8 when a termination signal is detected in the processing circuit 14.

The operation will be explained below. The oat l is detected by the non-modulation detection circuit 16.
Immediately after detecting the ll signal, the counter 12 is sent to the filter 7 by the timing circuit 8 at the output of the non-modulation detection circuit 16.
A timing signal for capturing the output is output. Based on this timing signal, the counter 12 can detect the start signal and end signal. Moshide counter 1
2, sampling is performed 16 times as shown in FIG.
3 takes in the output of the counter 12 and identifies whether it is a start signal. When the output of the counter 12 is equal to or greater than a predetermined value, it is determined that the input 1-bit signal is 1'' and outputs it to the processing circuit 14.The output of the judgment reference circuit 13, which is sequentially output in this way, is sent to the processing circuit. 14 reads and compares the start signal pattern and the end signal pattern stored in the memory 15 to identify the start signal or the end signal.When the processing circuit 14 identifies the start signal, the control circuit uses the output of the processing circuit 14. 17 operates to drive the amplifier circuit 5 described in the conventional example to emit sound from the speaker 6.Mar-1 The subsequent processing circuit 14 identifies the end M+, and when t-, the control circuit 17 drives the amplifier circuit 5. The operation of the timing circuit 8 is stopped, and the start signal or the end (when the f! signal is not received, the timing circuit 8
The operation of the timing circuit 8 is stopped to prevent the output from occurring, and the timing circuit 8 is returned to a standby state. Note that even if an unmodulated signal is input during signal capture, the device returns to the standby state in the same way. In this way, in this embodiment, the 16-bit shift register 9, register 11, and comparator circuit 10 are not required, so the circuit can be miniaturized, and even if the emergency warning signal detection circuit 4 is implemented using a microprocessor, It requires less RAM area.

(Embodiment 3) FIG. 4 shows an emergency alert (N call detection circuit 4) according to still another embodiment of the present invention.
As shown in the figure), the output of the filter 7 was sent to the counter 12, and the counting operation was started at the same time as the output of the non-modulation detection circuit 16 was generated. arise. Therefore, in this embodiment, as shown in FIG. 5, a timing adjustment circuit 18 is provided which does not perform sampling during the delay time, but performs sampling intensively after the output of the filter 7 has stabilized. After the output stabilizes like this, if you concentrate on sampling the same number of times,
Although the sampling time will be shorter, the sampling frequency will be reduced in order to sample during the period when the output is stable.1. But it has no effect. In this way, by not sampling during the period when the output of the filter 7 is not stable, the reliability of signal identification is improved.

[Effects of the Invention 1] As described above, the present invention provides an emergency warning broadcast receiver that receives emergency warning broadcasts including frequency shift keying signals of two frequencies, including a tuning circuit that tunes broadcast radio waves and an output from the tuning circuit. A demodulation circuit that demodulates to the audio band, a non-modulation detection circuit that detects non-modulation based on the signal of the tuning circuit, a non-modulation detection circuit, and f! An emergency alarm signal detection circuit that detects an emergency alarm signal consisting of a start signal and an end signal using the output of the regulator circuit; Since the control circuit is equipped with a control circuit that returns to the state of Even if a prank signal is received by the emergency warning broadcast receiver, this signal will not normally be included in the broadcast radio waves, so It is determined that the signal is not an emergency warning signal, the emergency warning broadcast receiver malfunctions, and a strange broadcast is not broadcast to confuse viewers.

[BRIEF DESCRIPTION OF THE DRAWINGS] Fig. 1 is a circuit diagram of the main part of one embodiment of the present invention, Fig. 2 is a circuit diagram of the main part of another embodiment of the invention, and Fig. 3 is the same as above. 4 is a circuit configuration diagram of a main part of still another embodiment of the present invention, FIG. 5 is an explanatory diagram of the same operation as above, FIGS. 6 to 8 are explanatory diagrams showing emergency warning signals, ! Figure #9 is a circuit configuration diagram showing a conventional example, 1 (Figure 1 is a circuit configuration diagram of the main parts of the same as above. 2 is a tuning circuit, 3 is a demodulation circuit, 4 is an emergency warning signal detection circuit, and 5 is an amplifier circuit. , 16 is a non-modulation detection circuit, and 18 is a control circuit.

Claims (3)

[Claims] (1) In an emergency warning broadcast receiver that receives emergency warning broadcasts including frequency shift keying signals of two frequencies, a tuning circuit that tunes the broadcast radio waves, a demodulation circuit that demodulates the output from the tuning circuit into the audio band, and a tuning circuit that tunes the broadcast radio waves. A non-modulation detection circuit that detects non-modulation based on a circuit signal, an emergency alarm signal detection circuit that detects an emergency alarm signal consisting of a start signal and an end signal from the outputs of the non-modulation detection circuit and the demodulation circuit, and an emergency alarm signal detection circuit. 1. An emergency warning broadcast receiver comprising: a control circuit which operates the device after a start signal according to an output, and returns to the original state by an end signal after the start. (2) The emergency warning broadcast receiver according to claim 1, wherein the emergency warning signal detection circuit starts receiving the demodulated signal based on the output of the non-modulation detection circuit. (3) The emergency warning broadcast receiver according to claim 2, wherein the demodulated signal is taken in after the output from the demodulation circuit becomes stable.