Title:
SIGNAL TRANSMISSION SYSTEM AND ITS GENERATING DEVICE
Document Type and Number:
Japanese Patent JPS6376593
Kind Code:
A
Abstract:
PURPOSE:To contrive improvement of the stability of the orthogonality of signals in the transmission and the reception of an orthogonal multiplex signal by modulating a carrier wave with a multiplex signal other than a video signal securing the orthogonality against the video signal, and transmitting the result. CONSTITUTION:A video signal carrier wave which is phase-shifted by approximately ninety degrees by a phase shifter 11 is modulated by a digital modulation circuit 12 by using a digital-coded voice, and its output is supplied to an adder 13 where it is added with a video transmission signal. As a result, a carrier wave for video is modulated orthogonally with the video signal and the digital- coded sound, signal. By the phase detector 17 incorporated in a circuit 16 to monitor the orthogonality, the phase difference between the video signal output of an amplitude modulation circuit 6 and the output of a digital modulation circuit 12, then an arithmetic circuit 18 calculates the difference between the phase difference and a prescribed phase difference in order that the phase shifter 11 is controlled through a low-pass filter 19. As a result, the orthogonal multiplex can be executed more stably.
Inventors:
NODA TSUTOMU
TANAKA HIROMICHI
SHIROSUGI TAKATOSHI
TANAKA HIROMICHI
SHIROSUGI TAKATOSHI
Application Number:
JP21936986A
Publication Date:
April 06, 1988
Filing Date:
September 19, 1986
Export Citation:
Assignee:
HITACHI LTD
International Classes:
H04J11/00; H04N7/08; H04N7/081; (IPC1-7): H04J11/00; H04N7/08
Attorney, Agent or Firm:
Katsuo Ogawa