Smear signal perturbations-compensating circuit in satellite television receivers

摘要

2.1 In band-limited frequency-modulated transmission systems such as the transmission of television signals via satellites, a dispersal signal is superimposed onto the television signal to be transmitted before it is frequency-modulated. This leads to disturbances in satellite television receivers. In a known circuit, a correction signal characterising the amplitude of the dispersal signal is generated by evaluating the synchronisation signals and this correction signal is additively superimposed on the input signal. The novel circuit should also provide for compensation of the disturbances caused by the dispersal signal if no standard-oriented synchronisation signals are available. 2.2 This is achieved by means of a circuit which generates overshoots on a reference level of the signal. These overshoots, which differ from the useful signals with respect to their level are evaluated with respect to amplitude and used for generating the correction signal. 2.3 Satellite television receiver. IMAGE