JPS6328370B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an emergency warning receiver, and in particular to an emergency warning receiver equipped with a reception system that allows emergency broadcasts to be always heard in optimal reception conditions even in mobile receivers such as so-called portable radios and car radios. Regarding the receiver.

There is a strong possibility that an emergency broadcast system will be implemented as an emergency disaster countermeasure against large-scale earthquake disasters that are expected to occur in the near future. The purpose of this system is to ensure that all residents are accurately and quickly informed of emergency information in the event of a disaster. As a means of this system, the receiving side uses a receiver that can also receive broadcast radio waves on which emergency warning signals are superimposed, and recognizes emergency warnings based on the generation of alarm sounds, power operation of the receiver, etc. It is something.

In the event of an emergency, the broadcasting station broadcasts emergency warning information modulated into so-called FS all at once, but the receiving side must be prepared to optimally receive this information. Therefore, in the case of so-called home use radios and component tuners, in which a receiver with a built-in emergency alert reception system is always installed in a fixed location, the emergency broadcast frequency (for example,
If you tune in to NHK 1st broadcast or a specific local station, you can always expect optimal operation in an emergency. On the other hand, there is a problem with mobile receivers (for example, so-called portable radios, car radios, etc.) in which the receiver is always on the move. In other words, it is extremely difficult to listen to emergency broadcasts in optimal reception conditions because, firstly, the received field strength constantly changes, and secondly, it is not always tuned to a fixed emergency broadcasting frequency. be.

Therefore, the present invention was made in view of the above-mentioned problems, and its main purpose is to provide an emergency warning receiver equipped with a reception system that allows emergency broadcasts to be listened to in optimal reception conditions at all times even on a mobile receiver. There is a particular thing.

To summarize this invention, PLL (Phase Locked
Loop) In a receiver having an electronic tuner system, a means for automatically detecting the presence or absence of an emergency broadcast, a means for automatically searching each broadcasting station and detecting the electric field strength of the received frequency, and a means for automatically detecting the presence or absence of an emergency broadcast, a means for automatically detecting the electric field strength of the receiving frequency, and a means for automatically detecting the presence or absence of an emergency broadcast, and The present invention is characterized in that the receiver is always on standby so that it can receive emergency broadcasts in an optimal reception state, and includes means for determining whether it is broadcast reception from both demodulated outputs.

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

FIG. 1 is a block diagram of a receiver having an emergency alert receiving function as an embodiment. In its configuration, AT is an antenna for receiving broadcast radio waves,
1 amplifies the signal received by antenna AT
RF amplification circuit 2 is a frequency conversion circuit (hereinafter referred to as mixer) that mixes the output from the frequency synthesizer PLL and the output of RF amplification circuit 1 to output an intermediate frequency signal; 3 is an intermediate frequency amplification circuit ( 4 is an audio signal demodulation circuit into which the output of the intermediate frequency amplification circuit 3 is input, and the output of the circuit 4 is given to the microcomputer 10. As is well known, the frequency synthesizer PLL consists of a voltage controlled oscillation circuit 5, a frequency division circuit 6 consisting of a group of counters, a comparison frequency oscillation circuit 7, a phase detection circuit 8 as a multiplier, and a low-pass filter 9. Depending on the frequency division ratio set in the frequency circuit 6, it acts as a multi-frequency switching device. A frequency division ratio signal from the microcomputer 10 is applied to the frequency division circuit 6 of this frequency synthesizer PLL.

11 is an emergency broadcast signal demodulation circuit into which the output of the IF amplification circuit 3 is input, and 12 is an emergency broadcast determination circuit. Both of these are normally digital circuits, and for example, they automatically determine the presence or absence of an FSK-modulated emergency broadcast. The output thereof is provided to the microcomputer 10. 13 is a manual switch for giving an automatic tuning command to the microcomputer 10; Reference numeral 14 denotes an electric field strength detection circuit to which the output of the IF amplification circuit 3 is input and for detecting the electric field strength of broadcast radio waves, and the analog signal from the circuit 14 is digitized by the A/D conversion circuit 15. is given to the microcomputer 10.

A detection circuit 16 is connected to the audio signal demodulation circuit 4 to detect the DC level of the demodulated (detected) signal, and supplies the detected DC level signal to the level comparison circuit 17. The level comparison circuit 17 is a circuit for determining the audio level by comparing the DC level with a voltage level higher than a preset noise level, and the comparison result output is given to the microcomputer 10. Note that the above configuration shows only the core circuit, and includes the power supply circuit,
Audio circuit (including low frequency amplification circuit, speaker, etc.)
and other auxiliary circuit means are omitted.

In the operation, the normal reception mode is omitted because it is well known, and the operation mainly related to the frequency synthesizer PLL and the flowchart shown in FIG. The operation of the receiver will be explained.

The frequency synthesizer PLL sets the local frequency, and provides the mixer 2 with a specific frequency signal for selecting a target local station from the radio signal from the RF amplification circuit 1. A local station selection command is manually input to the microcomputer 10 by means of a switch or the like. The microcomputer 10 gives a frequency division ratio signal according to this command signal to the frequency dividing circuit 6, and fixes the output frequency of the voltage controlled oscillation circuit 5 to a frequency that has a constant relationship with the comparison frequency (constant) from the comparison frequency oscillation circuit 7. do. The signal converted to an intermediate frequency by the mixer 2 is amplified and then input to the emergency broadcast signal demodulation circuit 11, the audio signal demodulation circuit 4, and the electric field strength detection circuit 14. It is assumed that the circuits 11 and 12 are always powered on).

Now, listeners are using their receivers to select the best received broadcast (broadcasting station that they can hear most strongly and clearly in their own radio wave area).
For example, tune to NHK 1st broadcast, etc.). Note that if no particular broadcast station is selected, the frequency may be tuned to the emergency broadcast frequency. In this state, step _S1 of the flowchart of FIG. 2 is executed. That is, the magnitude of the electric field strength at the frequency of the broadcasting station detected by the electric field strength detection circuit 14 is stored in the memory of the microcomputer 10. In this way, the initial values of the optimal reception frequency (Fop) and optimal reception field strength (Eop) of the current system are set. In step S ₂ ,
It constantly detects whether there is an emergency alert issued using a specific modulation method (for example, FSK method). This is the emergency broadcast signal demodulation circuit 11 in FIG.
Based on the signal given to the microcomputer 10 by the emergency broadcast determination circuit 12, the microcomputer 10 itself (of course, based on a preset program) makes the determination. step
When the start of an emergency broadcast is detected in S ₂ , the step
Move to _S3 and listen to the emergency warning broadcast. However, due to reasons such as moving the receiver (for example, when you are listening to a car radio while moving in a car, or when you are carrying a portable radio), some stations may be unknowingly set. The reception condition is extremely poor, as it may be impossible to receive important emergency broadcasts because the emergency broadcasts are flying out of the area. When the reception condition is poor like this, the automatic search start switch 13 sends an automatic search request.
(Figure 1). This is judgment step S ₄
It is. When a command is given to the microcomputer 10 by turning on the switch 13, the microcomputer 10 automatically starts searching (step S ₆ in FIG. 2). Note that even if there is no emergency broadcast in step _S2 , step _S5 is provided so that automatic search can be performed using the switch 13 if there is a need to perform an automatic search due to reasons such as movement of the receiver. This functions advantageously for resetting, for example, when it is clear that the user's current location is out of the previous radio wave area.

After starting the automatic search, step S ₇ and step
As shown in _S8 , the presence or absence of a broadcasting station is determined by detecting the carrier wave level (corresponding to electric field strength), and the electric field strength signal at the receiving frequency of the station is A/D converted and sent to a microcomputer. 10 in memory. This operation is performed by the field strength detection circuit 14 and A/D conversion circuit 15 shown in FIG. In the next step _S9 , the electric field strength (Es) which has just been A/D converted is compared with the optimum received electric field strength (Eop). Of course microcomputer 1
Depends on the program or calculation means inside 0. If the determination that Eop<Es is true within the computer 10, the process advances to step _S10 . This is because only by detecting the electric field strength (carrier wave level), it is not possible to determine whether it is an actual broadcast reception or a simple unmodulated carrier wave. In step _S10 , the DC level of the demodulated output is detected. This is accomplished by circuit 16 of FIG. The detected demodulated signal DC level is compared with a preset noise level in the level comparison circuit 17, and if it corresponds to the audio level, it is determined that the received signal is an actual broadcast reception (step _S11 ). In step _S12 , the step
Since Eop<Es in _S9 , the memory is rewritten with Es set as the new optimum received electric field strength, and the memory is rewritten with the received frequency Es in the electric field set as the optimum received frequency. When the process of step _S12 is completed, the process returns to the initial state and returns to step _S2 . By passing through the flow from step _S2 to step _S12 several times, the station is set to the strongest station in the radio wave area at the position of its own receiver. Note that if the judgment conditions are not satisfied in the judgment steps S ₅ , S ₇ , S ₉ , and S ₁₁ , all return to the initial state. That is, in decision step _S9
If Eop>Es, the optimal reception frequency op remains unchanged and returns to the initial state; on the other hand, even if the condition of Eop<Es is satisfied, if no audio signal is detected in step _S11 , the same returns to the initial state. .

The flowchart shown in FIG. 2 is for explaining the system operation of this embodiment. Although some of the execution steps are performed by some of the circuit blocks shown in FIG. The steps and operation sequences are operated or controlled based on a software program preset in the ROM or the like inside the microcomputer 10 shown in FIG. Such an embodiment using a microcomputer (which may also be a microprocessor) as a control means for controlling individual control operations can be designed without much difficulty by those skilled in the art.

As described above, by automatic tuning of the emergency warning receiver, the receiver can always be kept on standby at the optimum receiving frequency. In other words, even if a vehicle-mounted receiver is moving and unknowingly moves out of the set station area and is set in a state where it cannot normally receive emergency broadcasts, the external automatic search start switch can be activated. Automatic tuning can be started by operating . If the receiver is fixedly installed, the automatic search switch 13 may be turned off and set to the emergency broadcast frequency in advance.

Furthermore, in the above embodiments, the description has been made assuming an AM broadcasting receiver, but the invention is not limited to this, and may be applied to an FM broadcasting receiver or even an audio circuit (FM receiving circuit) of a television receiver. . Those skilled in the art will easily understand this.

As described in detail above, the present invention has the effect that emergency broadcasts can always be listened to in optimal reception conditions even with a mobile receiver.

[Brief explanation of the drawing]

FIG. 1 is a block diagram as an embodiment of the present invention, and FIG. 2 is a flowchart for explaining the system operation that allows the receiver of FIG. 1 to always listen to emergency broadcasts in optimal reception conditions. . 1...RF amplification circuit, 2...Frequency conversion circuit,
3... Intermediate frequency amplification circuit, 4... Audio signal demodulation circuit, PLL... Frequency synthesizer, 6... Frequency division circuit, 10... Microcomputer, 11...
Emergency broadcast signal demodulation circuit, 12...Emergency broadcast determination circuit, 13...Automatic tuning start switch, 1
4...Field strength detection circuit, 16...Demodulated signal DC
Level detection circuit, 17...Level comparison circuit.

Claims (1)

[Scope of Claims] 1. A frequency conversion circuit that converts an output from a PLL circuit into an intermediate frequency, and a control means that provides a frequency division ratio to the PLL circuit, and that includes a storage means and controls predetermined control operations. means for automatically detecting the presence or absence of emergency broadcasts modulated by a specific method, and means for automatically searching each broadcasting station and detecting the electric field strength according to the frequency of the broadcasting station The receiver is equipped with a means for determining whether broadcast reception is being received based on both the carrier wave level and demodulation output, and is always on standby so that the receiver can receive emergency broadcasts in an optimal reception state. emergency alert receiver.