Diversity Performance in Frequency-Hopped 8-ARY Signals-Implementation andMeasurements

摘要

A micro-processor based signal processor was built and tested that is capable ofperforming the diversity combining need to reduce the error rate of 8-ary non-coherent FSK signals demodulated onboard a satellite. Two combining techniques were implemented and tested: hard decision majority vote (HDMV) and normalized envelope detection (NED). Measurements of bit error rate performance of these two techniques in the presence of system noise plus either partial-band noise (PBN) or multiple tone (MT) jamming were made for levels of diversity, L, from 1 to 32. The signal-to-jammer ratio (SJR) levels used were so low that worst-case jamming was always with the full band jammed. Results showed that HDMV combining could give error correction for PBN jamming for a SJR as low as O dB but gave no correction for MT jamming when the SJR was less than 10 dB even for L as high as 32. NED combining handled PBN jamming better than the HDMV and performed very well against MT jamming even at a SJR as low as odB. Results show for the low SJR regime considered, that NED combining is clearly the error correction method of choice over HDMV combining and even over low-rate convolutional coding.