SIGNAL PROCESSING SYSTEM FOR TELEVISION RECEIVER HAVING ACOUSTIC SURFACE WAVE DEVICES FOR IMPROVED TUNING AND VIDEO DEMODULATION

摘要

This disclosure depicts a number of signal processing circuits for a television receiver which include acoustic surface wave devices for improved tuning and video demodulation. In each embodiment an IF stage has an acoustic surface wave bandpass filter. In one embodiment a reference oscillator forming part of a synchronous video detector and also part of an APC loop has a frequency-selective surface wave filter for establishing its frequency of oscillation. Another embodiment has an AFC circuit including a surface wave discriminator. In all embodiments the acoustic surface wave devices have similar thermal characteristics and thermal exposure so as to cause temperature tracking of the frequency characteristics thereof and thereby to temperature stabilize the receiver. The surface wave filter devices which are associated in the disclosed systems may utilize thermally homogeneous piezoelectric substrate means.