| 摘要 |
A diversity receiver includes a multipath transmission detector which, upon detecting multipath distortion of a received angle-modulated input signal, switches to an alternative receiving antenna. If such a receiver has high selectivity, the detector may be erroneously triggered by weak received signals. To prevent this, the receiver is provided with a narrow band frequency window circuit which inhibits detection of multipath distortion when the instantaneous frequency of the input signal is outside the frequency window. The frequency window circuit may comprise a level detector connected to the receiver demodulator or connected by a bandpass filter to the R.F. mixer stage of the receiver.
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