JPS63140741U

JPS63140741U -

Info

Publication number: JPS63140741U
Application number: JP1987033342U
Authority: JP
Priority date: 1987-03-06
Filing date: 1987-03-06
Publication date: 1988-09-16

Description

[Brief explanation of the drawing]

第１図はこの考案の実施例を示す電気ブロツク
図、第２図ａはマイクロホンから出力される音声
信号の周波数スペクトラムを示す図、第２図ｂは
送信機の低域フイルタを通過した音声信号と、パ
イロツト信号との混合信号の周波数スペクトラム
を示す図、第２図ｃは、受信機の低域フイルタを
通過した音声信号の周波数スペクトラムを示す図
、第３図は受信部の変形例を示す電気ブロツク図
、第４図は従来例を示す電気ブロツク図、第５図
ａはマイクロホンから出力される音声信号の周波
数スペクトラムを示す図、第５図ｂは音声信号と
パイロツト信号との混合信号の周波数スペクトラ
ムを示す図である。１０……送信機、１２Ａ……パイロツト信号発
生回路、１３……ＦＭ変調回路、２０……受信機
、２３……ＦＭ復調回路、２５……低周波増幅回
路、２８……スケルチ回路、３１……低域フイル
タ、３２……低域フイルタ。 Figure 1 is an electrical block diagram showing an embodiment of this invention, Figure 2a is a diagram showing the frequency spectrum of the audio signal output from the microphone, and Figure 2b is the audio signal that has passed through the low-pass filter of the transmitter. Figure 2c shows the frequency spectrum of the audio signal that has passed through the low-pass filter of the receiver, and Figure 3 shows a modified example of the receiver. Fig. 4 is an electrical block diagram showing a conventional example, Fig. 5a is a diagram showing the frequency spectrum of an audio signal output from a microphone, and Fig. 5b is a diagram showing a mixed signal of an audio signal and a pilot signal. FIG. 3 is a diagram showing a frequency spectrum. 10...Transmitter, 12A...Pilot signal generation circuit, 13...FM modulation circuit, 20...Receiver, 23...FM demodulation circuit, 25...Low frequency amplifier circuit, 28...Squelch circuit, 31... ...Low pass filter, 32...Low pass filter.

Claims

[Claims for Utility Model Registration] A pilot signal generation circuit that generates a pilot signal whose frequency is in the high range of the audio frequency band; A transmitter having a low-pass filter, and a modulation circuit that FM-modulates a carrier wave with a mixed signal of a pilot signal and an audio signal that has passed through the first low-pass filter, and a modulating circuit that modulates a carrier wave using a mixed signal of a pilot signal and an audio signal that has passed through the first low-pass filter, and a modulated wave that is mixed from a modulated wave sent out from the transmitter. An FM demodulation circuit that reproduces the signal, a second low-pass filter that removes the pilot signal from the reproduced mixed signal and passes the audio signal, an output circuit provided after the second low-pass filter, and an FM demodulation circuit. To permit audio signal input to the output circuit when the pilot signal is included in the output of the circuit, and to prohibit audio signal input to the output circuit when the pilot signal is not included in the output of the FM demodulation circuit. An FM communication device comprising: a receiver having a squelch circuit;