Abstract: In an encoding circuit for the S.E.C.A.M. color television standard a signal value is added to each one of two line-sequential color difference signals to determine the quiescent frequencies. The modulating signal containing the color difference signals is subjected to double sided amplitude limitation. The ratio of the level difference between the limitation limits to the difference between the added signal values is substantially constant. The signal path for the modulating signal to the FM-oscillator comprises a controllable amplifier, limitation being effected first followed by amplification.

Abstract: 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.