| 摘要 |
<p>PROBLEM TO BE SOLVED: To reject interference of an identical channel by filtering an interference signal using an FIR filter in a carrier reproducing loop. SOLUTION: An output from an input processing circuit 12 is supplied to a rotator 16 through a feedforward equalizer 14. An identical channel notch filter 18 processes a base band outputted from the rotator 16 or a signal close to the base band. The filter 18 exhibits a zero through-put delay band pass response with attenuation notches for rejecting an NTSC-identical channel base band video carrier and chrominance subcarrier frequency. The filter 18 advantageously improves the performance of the equalizer 14 so that a proper coefficient control signal is applied from a multiplier 30 to the equalizer 14. Since the filter 18 is included in the carrier reproducing loop for reproducing the base band signal, the identical-channel-interference rejecting notch of the filter 18 accurately coincides with the frequency of the base band signal to be rejected.</p> |
