Title:
DISCRIMINATION CIRCUIT OF TELEVISION SIGNAL
Document Type and Number:
Japanese Patent JPS62142475
Kind Code:
A
Abstract:
PURPOSE:To discriminate the presence of a television signal accurately up to a weak electric field by using a detection output of a voltage level integrated by the 1st filter so as to control a time constant of the 2nd filter thereby discriminating the presence of the television signal from the 2nd filter. CONSTITUTION:A horizontal synchronizing signal is extracted by a horizontal blanking pulse and smoothed separately by the 1st filter comprising a capacitor C1 and a resistor R1 and the 2nd filter comprising a capacitor C2 and resistors R2, R3 respectively. That is, the 2nd filter has a time constant of C2XR3 over an electric field strength A and a time constant of C2X(R2+R3) below the electric field A. Since the filter voltage is D in the 2nd filter at a point of an electric field strength C, the presence of a television signal is discriminated with the electric field strength C or over.
Inventors:
HOSONO MASAKI
Application Number:
JP28353585A
Publication Date:
June 25, 1987
Filing Date:
December 17, 1985
Export Citation:
Assignee:
MATSUSHITA ELECTRIC IND CO LTD
International Classes:
H04N5/44; (IPC1-7): H04N5/44
Attorney, Agent or Firm:
Toshio Nakao