U.S. Philips Corporation

Hermann Treber

Siegfried Bohme

Dieter Gutsmann

Eckhart Pech

For the possibly simultaneous A/D conversion of two color difference signals of a first picture signal as well as a carrier-frequency chrominance signal of a second picture signal, a relevant circuit arrangement is provided with a multiplexer (3) by which a time-division multiplex signal is generated from the two color difference signals, in which time-division multiplex signal the two color difference signals alternate in time and which is added to the chrominance signal in an adder (5) to form a sum signal which is applied to an A/D converter (10) which is followed by a separating filter (11) for separating the digital time-division multiplex signal from the digital chrominance signal.

Circuit arrangement for A/D conversion of the color information

A circuit arrangement for identifying the transmission standard of a color television signal, having a chrominance subcarrier upon which chrominance information is modulated and color synchronising pulses, includes circuitry (14, 21, 24, 25) for determining the frequency of the chrominance subcarrier which, in those cases in which a given standard of the color television signal can unambiguously be concluded from the determined chrominance subcarrier frequency of the color television signal to be decoded, the decoder is immediately switched to the decoding of this signal of this standard, and in addition includes circuitry (23, 22) which determine the vertical deflection frequency of the television signal and ascertain whether the chrominance subcarrier has a line-sequentially alternating phase, and that in those cases in which the determined chrominance subcarrier frequency cannot unambiguously be assigned to a given standard, these information components are also used for identifying the standard of the color television signal to be decoded and for adjusting the decoder to this standard, in addition to the chrominance subcarrier frequency.

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Hamburg, Germany

Hermann Treber