ENCODING CIRCUIT FOR A SECAM COLOUR TELEVISION TRANSMISSION

摘要

An encoding circuit for a SECAM color television transmission, comprising a frequency-modulatable oscillator for a modulating signal which comprises two line-sequential color difference signals, the circuit also comprising a control loop for making the quiescent frequencies in the generated frequency-modulated signal substantially equal to reference frequencies. For this purpose the control loop comprises a multiplexer, a frequency demodulator and two control paths each having two sample- and -hold circuits. The sequence of the signals conveyed by the multiplexer and the time position of the measuring intervals are chosen such that at least a line scan period is located between the quiescent frequency-measuring interval and the reference frequency-measuring interval.