IDENTIFYING CIRCUIT FOR DIAL-IN PULSE SIGNAL AND CALLING SIGNAL OF TELEPHONE SET

Title:

IDENTIFYING CIRCUIT FOR DIAL-IN PULSE SIGNAL AND CALLING SIGNAL OF TELEPHONE SET

Document Type and Number:

Japanese Patent JPS5465404

Kind Code:

A

Abstract:

PURPOSE: To prevent the malfunction of the facsimile device or the like through identification between the calling signal and the dial-in pulse by monitoring the frequency and the time of the input signal via the timer circuit.

CONSTITUTION: The input signals of the dial-in pulse and calling signal are supplied to pulse formation circuit 2 via half-wave rectifier circuit 1. The pulse is delivered with every period of the input signal. With his pulse, the frequency of the input signal is monitored through timer circuit 3, and the continuous transmission time of the input signal is monitored through timer circuit 4 based on the monitor output. As a result, an identification becomes possible between the supplied dial-in pulse of a high or low frequency and the calling signal.

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Inventors:

OKUTSU KAZUHIKO
KATAOKA NORIO
SHIMIZU HARUMITSU
INAGAKI HIRONARI
IZUMI GOROU

Application Number:

JP13223277A

Publication Date:

May 26, 1979

Filing Date:

November 04, 1977

Export Citation:

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Assignee:

NIPPON TELEGRAPH & TELEPHONE
TAMURA ELECTRIC WORKS LTD
OKI ELECTRIC IND CO LTD

International Classes:

H04M1/00; H04M1/64; H04M11/00; H04M11/06; (IPC1-7): H04M1/21

Previous Patent: JPS5465403

Next Patent: SYNCHRONIZATION CONTROL SYSTEM FOR TERMINAL STATION