Combiner Performance Using Narrow-Band Noise Filtering and Enhanced Squelch

The use of "narrow-band" noise filters in the combiner control circuits of a quadruple-diversity post-detection combiner was found to reduce the average bit-error rate by a factor of 4.6; while the median output signal-to-noise ratio was increased by 2 dB. The use of an "enhanced-squelch" control of the postdetection combiner increased the output voice-channel signal-to-noise ratio by 3 dB, and effectively eliminated a high percentage of the noise bursts in the voice channels.