Coding for Navy UHF Satellite Communications CODEC EValuation Study

摘要

The NAVELEX breadboard codec performance has been verified in the uncoded and coded modes at all code rates. The operation of the data interleaver/deinterleaver and differential encoder/decoder has also been substantiated in the performance tests. Both the 1-bit hard decision and the 3-bit soft decision decoder modes are operational. Initial difficulties in the checkout phase were determined to originate in a defective -5 volt power supply module, which is being replaced. It was also necessary to perform some minor adjustments to the AGC gain block D.C. bias control (R8). Through careful adjustment of this bias control, an acceptable signal output to the quantizer-bit synchronizer was obtained. This nulling adjustment allows for optimum coder-decoder performance in the presence of zero-mean noise, by eliminating the D.C. offset present at the quantizer input.