| 摘要 |
<p>The TV receiver has a detection circuit (13) of which one input is coupled to the output of a mid frequency converter (9). The detection circuit (13) is also coupled to a band filter (31) which is controlled via two oscillators (33 and 37) tuned to video mid frequency, the power being derived from a power supply with phase shift (28 and 25). HF input signals are converted to mid-frequency in a mixer (3) controlled by an oscillator (7) which is coupled to the output (19) of the first detector (17). Inputs, (15 and 23) to the first detector (17) are derived from the mid-frequency convertor (9) and phase shifter output (25). Inputs (41 and 45) to the second detector (43) are derived from the mid-frequency converter (9) and the tuned bandfilter (31). The first detector (17) thus acts as an AFC detector, and the second (43) acts as video signal detector. The circuit is intended to improve separation of video and sound signals resulting in reduced video to sound cross-talk and improved sound reproduction.</p> |
