| 摘要 |
A circuit arrangement for obtaining a control quantity which is dependent on the phase shift of a color burst signal comprising an amplitude factor with respect to a reference signal, preferably of approximately the same frequency, which is phase-locked to a clock signal with which the amplitude values of the color burst signal are sampled and whose frequency is the 4n-fold of the frequency of the reference signal. n is an integer and the keying occurs in such manner that a first sampled difference signal obtained by the sampling and a second sampled difference signal shifted by a quarter of a cycle of the color burst signal, are obtained which are proportional to the amplitude of the color burst signal. For evaluating as directly as possible the phase error independently of the amplitude factor, at least one sampled difference signal (X and Y, respectively) is divided by the amplitude factor (A) in a conversion stage (55) in such manner that at least one phase-sensitive control quantity is obtained which consists substantially of sin- and/or cos-members of the phase angle ( alpha ), optionally of a sum or a difference or a product thereof which is at least substantially independent of the amplitude factor.
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