| 摘要 |
<p>A video carrier recognition system for use with a signal seeking television receiver tuner or the like includes a plurality of detectors for recognizing certain conditions indicating that the receiver is appropriately tuned to a video carrier signal. The conditions comprise AFC system lock, the presence of a relatively low peak duty cycle characterizing the low-pass filtered output of the receiver's video detector and the absence of a relatively large amplitude 1.5MHz beat note at the output of the video detector. In addition, noise immunity may be provided by requiring correlation between the low-pass filtered output of the video detector and the horizontal flyback pulses developed in the horizontal deflection system of the receiver.</p> |
