| 摘要 |
<p>The interference suppression system for a frequency modulated UHF stereo signal from which a pilot signal is filtered out, is used for a common aerial system for community television. The filtered pilot signal is passed to a further filter system using a narrow band filter and a phase corrector to reduce the remaining interference. The interference force signal then enters a modulator stage in the path of the earlier filter system to obtain the required stereo signal. In an alternative system, the filter system uses a phase-locked loop oscillator with a narrow band filter, the output of the oscillator being modulated to obtain the stereo signal. An automatic level control stage is used to control the oscillator when the pilot signal is not converted into the stereo signal.</p> |
