摘要 |
<p>DIGITAL DEMODULATOR A demodulator for differentially coherent phaseshift keyed data signals correlates samples taken in consecutive baud intervals. Depending on the results of at least two such correlations or lack thereof, counts are registered in unidirectional counters supplied with thresholds related to preassigned counts per baud interval. Bistable circuits respond to the attainment, or failure of attainment, of the threshold-count levels during each baud interval, after which the counters are reset to a reference level. The states of the bistable circuits directly represent binary data without further logic operations in the four-phase case particularly.</p> |