Title:
TWO-WIRE TYPE SUBSCRIBER LINE TRANSMISSION SYSTEM
Document Type and Number:
Japanese Patent JPS57162845
Kind Code:
A
Abstract:
PURPOSE: To provide a gain to a subscriber circuit through the avoidance of ringing, by transmitting incoming and outgoing audio with separation through the use of two-wire lines.
CONSTITUTION: A communication DC current is applied to a transmitter from a subscriber circuit. The audio signal from the transmitter is transmitted to a coder COD through branching filters FILS and FILM. The audio from a decoder DEC is amplitude-modulated with a modulation frequency (f) at a modulator MOD. The modulation signal is demodulated into the original audio signal at a demodulator DEM through the filters FILM and FILS and applied to the receiver. 16∼32kHz are most suited to the modulation frequency (f).
Inventors:
HISAMURA MAKOTO
Application Number:
JP4719081A
Publication Date:
October 06, 1982
Filing Date:
April 01, 1981
Export Citation:
Assignee:
HITACHI LTD
International Classes:
H04B3/00; H04M1/78; (IPC1-7): H04B1/00; H04B3/50
Domestic Patent References:
| JP49082613B |