TELEVISION RECEIVER FOR TUNING A SIGNAL INCLUDING A PILOT SIGNAL

摘要

The invention provides a method of operating a television receiver having a synchronous demodulator controlled by a frequency and phase locked loop for locking to a pilot signal in a tuned television signal, the frequency and phase lock loop including an AFC filter. The method comprises tuning a television signal, commencing a start-up interval of predetermined duration, and injecting a current into an output node of the AFC filter for producing a filter characteristic which prevents the phase response of the frequency and phase locked loop from reaching 180.degree. during the start-up interval. By another aspect a television receiver for tuning a television signal including a pilot signal includes a frequency and phase locked loop controlled synchronous demodulator for locking to the pilot signal. A microprocessor develops an AFC Defeat signal defining a start-up interval, and an AFC filter is provided in the frequency and phase locked loop. A charge pump is coupled to the AFC filter; the charge pump being activated by the AFC Defeat signal during the start-up interval for injecting a current into an output node of the AFC filter, for producing a filter characteristic which precludes the phase response of the frequency and phase locked loop from reaching 180.degree..