JPH0450948U

JPH0450948U -

Info

Publication number: JPH0450948U
Application number: JP9231490U
Authority: JP
Priority date: 1990-08-31
Filing date: 1990-08-31
Publication date: 1992-04-28

Description

[Brief explanation of the drawing]

第１図は、本考案に係る秘話機能を具えたコー
ドレス電話の一実施例を示すブロツク図、第２図
は、その動作を説明する為の音声信号の周波数ス
ペクトラムを示す図、第３図は、サブキヤリアの
周波数の切り換えタイミングの一例を示す図、第
４図は、従来の秘話回路を具えたコードレス電話
の例を示すブロツク図である。Ａ……親機、Ｂ……子機、１_１，１_２……回線
端子、２，１１，１６，２２……帯域通過フイル
タ、５，９，１８，２０……低域通過フイルタ、
３，１０，１７……変調回路、１０，２１……復
調回路、４，１４……マイクロコンピユータ、６
_１，６_２……無線回路、７，８……アンテナ、１
２，２３……水晶発振子、１３……送話器、１５
……受話器。 Fig. 1 is a block diagram showing an embodiment of a cordless telephone equipped with a secret call function according to the present invention, Fig. 2 is a diagram showing the frequency spectrum of an audio signal to explain its operation, and Fig. 3 is FIG. 4 is a block diagram showing an example of a cordless telephone equipped with a conventional secret line circuit. A...Base unit, B...Slave unit, 1 ₁ , 1 ₂ ...Line terminal, 2, 11, 16, 22...Band pass filter, 5, 9, 18, 20...Low pass filter,
3, 10, 17... Modulation circuit, 10, 21... Demodulation circuit, 4, 14... Microcomputer, 6
_1,6 ₂ ...Radio circuit, 7,8...Antenna, 1
2, 23... Crystal oscillator, 13... Transmitter, 15
...Telephone receiver.

Claims

[Claims for Utility Model Registration] (1) In a cordless telephone that includes at least a modulation circuit, a demodulation circuit, a microcomputer, a transmitting circuit, and a receiving circuit in each of the base unit and slave unit, the audio signal is supplied from the microcomputer by a voice signal. 1. A cordless telephone equipped with a secret call function, characterized by comprising a modulation circuit or a demodulation circuit that modulates a subcarrier and performs spectrum inversion. (2) Modulation in which the subcarrier supplied from the microcomputer is modulated by an audio signal in a cordless telephone in which the base unit and the slave unit are each equipped with at least a modulation circuit, a demodulation circuit, a microcomputer, a transmitting circuit, and a receiving circuit. circuit, and a demodulation circuit that receives a spectrally inverted audio signal, modulates a subcarrier supplied from the microcomputer with the audio signal, performs spectrum inversion again, and demodulates the original frequency spectrum, A cordless telephone equipped with a secret call function, characterized in that a microcomputer is equipped with means for switching the frequencies of subcarriers supplied to a modulation circuit and a demodulation circuit at appropriate times.