| 摘要 |
A selective call communication system (10) has a selective call device (100) for transmitting a frequency hopped spread spectrum signal (320) encoded as Reed Solomon code words and modulated as a four-level frequency shift keying (4FSK) signal. A base site transceiver (156) receives the signal on a plurality of narrow band channels. A digital signal processor (DSP)(152) performs a fast fourier transform on the signal to generate frequency samples. The DSP (152) has a comparator (342) that compares an 4FSK symbol to a predetermined threshold, a determinator (344), in response to the comparator (342), determines when there is an interference signal jamming the narrow band channel, an erasure marker (346) marks a position in the Reed Solomon symbol determined to be jammed as an erasure and an error correcting code (348) corrects errors in the Reed Solomon code words marked with erasures.
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