Performance of error control methods on a frequency hopping channel with high bit error rate

An experimental frequency hopping system for the high-frequency (HF) channel is presented. The possibility of jamming makes spread-spectrum techniques of interest for military communication over HD channels. In order to investigate the possibilities and problems with spread-spectrum on HF, an experimental system has been designed, built, and tested. Measurement results from field tests are included. It is shown that an FH system needs error control techniques to get high reliability for the different propagation conditions that are common on the HF channel. The performance of error-correcting codes for different types of channel models are discussed. The BCH (15, 5, 7) code is studied, and the resulting bit error probability after decoding is given as a function of the part of the errors which are erased, with the sum of errors and erasures as a parameter. It is shown that more than 80% of erasures is needed to obtain good performance