JPH0749878Y2 - Receiver failure detection circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a failure detection circuit for a dual radio receiver.

[Outline of device]

The receiving circuit of the duplicated radio is always in a standby state, and when the signal from the transmitter of the partner station is received, the limiter output voltage of the first receiver and the limiter output voltage of the second receiver are When the level difference of exceeds the specified value,
It is judged that the receiver with the lower level has deteriorated,
A monitoring circuit that generated an alarm was used.

With this method, it functions effectively when receiving a normal incoming signal, but there is a risk of malfunction when inputting external noise or interfering radio waves.

[Conventional technology]

A conventional method of the failure detection circuit of the duplicated radio receiver will be described with reference to FIG.

The signal received by the antenna 1 is input to the No. 1 receiver 3a and No. 2 receiver 3b by the distributor 2, and is demodulated by each of the above-mentioned receivers and output as a voice or a signal although not shown in this figure. Has been done. This is to connect the limiter output terminal 4a of the No. 1 receiver 3a to the non-inverting inputs of the differential amplifiers 8a and 8b in order to detect the reception failure, and similarly connect the limiter output terminal 4b of the No. 2 receiver 3b. It is connected to the non-inverting inputs of the dynamic amplifiers 8c and 8d. On the other hand, the high level detection reference voltage 6a is connected to the inverting inputs of the differential amplifiers 8a and 8c, and similarly the low level detection reference voltage 6b is connected to the inverting inputs of the differential amplifiers 8b and 8d.

Only the positive polarity of the outputs of the differential amplifiers 8a to 8d is taken out by the diodes 9a to 9d.
When the output obtained by inverting the output of 9d by the inverter 10b is satisfied by the AND circuit 12, the output signal is taken out to the output terminal 14 through the OR circuit 13. Similarly, the signal obtained by inverting the output of the diode 9b by the inverter 10a and the output of the diode 9c are input to the AND circuit 11, and when the condition is satisfied, the failure signal is output to the output terminal 14 through the OR circuit 13.

In this circuit connection, if the low level of the No. 2 receiver is not detected when the high level of the No. 1 receiver is detected, it is judged as the No. 2 receiver failure and the No. 2 receiver is also received. If the low level of the No. 1 receiver was not detected while the high level was detected by the machine, it was the method of making the No. 1 receiver a failure.

[Problems to be solved by the device]

In the above-mentioned circuit, even if the sensitivity characteristics of the No. 1 receiver and No. 2 receiver are normal, the difference voltage of the limiter voltage between No. 1 receiver and No. 2 receiver is generated due to large external noise and interfering noise. There were cases where false alarms were generated other than the receiver failure.

[Means for Solving the Problems]

The present invention intends to provide a stable monitoring circuit by adding a squelch voltage condition in addition to the limiter voltage comparison in order to pass the above drawbacks.

〔Example〕

 An embodiment of the present invention is shown below in FIG.

The circuit operation from the antenna 1 to the OR circuit 13 is the same as that shown in FIG. No. 1 receiver 3a squelch voltage output terminal 21
After the signals of a and the squelch voltage output terminals 21b of the No. 2 receiver 3b are passed through the OR circuit 22, the reception failure alarm signal is output to the output terminal 14 only when the condition is satisfied in the AND circuit 23. become.

With the above circuit configuration, even if there is a difference in the limiter voltage due to an external noise input or an interfering radio wave, etc., if the squelch voltage does not occur, it means that there is no reception input, and the receiver No false alarm is output as a monitoring circuit.

[Effect of device]

Needless to say, when a tone squelch circuit is provided in addition to the squelch voltage, the tone squelch voltage output condition is used for changing the squelch voltage to provide a more stable monitoring circuit.

[Brief description of drawings]

 FIG. 1 shows an embodiment of the present invention. FIG. 2 shows a conventional circuit. 2: distributor, 3a, 3b: receiver, 22; OR circuit.

Claims (1)

[Scope of utility model registration request] 1. In a duplexed receiver, the level difference between the respective signals is a specified value from a limiter output signal obtained from the first receiver and a limiter output signal obtained from the second receiver. In the monitoring circuit for making the above abnormal, the squelch signal obtained from the first receiver and the squelch signal obtained from the second receiver are ORed together.
A receiver failure detection circuit, wherein an alarm output is generated under an AND condition between an output and the abnormal signal.