IMPROVED DECISION DIRECTED PHASE LOCKED LOOP (DD-PLL) FOR USE WITH SHORT BLOCK CODES IN DIGITAL COMMUNICATION SYSTEMS

摘要

An improved digital decision directed phase locked loop (DD-PLL) for use withshortblock codes using phase shifting keying (PSK) modulation. The improvementinvolves aconventional digital phase lock loop which is modified to base its loopcorrections on the resultsobtained by decoding the short block code rather than on a symbol by symbolbasis as iscustomary in conventional DD-PLLs. The improved method of loop correctionsinvolvesretaining the symbol data pending the decoder's decision, derotating theretained data inaccordance with the decoded result, and integrating the derotated data to forma compositeestimator upon which to base the loop correction. In its preferred embodiment,the inventionuses an (8, 4) biorthogonal code with quatenary PSK.