In order to investigate the possibilities and problems with HF spread spectrum communication, an experimental frequency hopping (FH) system has been designed, built and tested at the National Defence Research Establishment in Sweden. The experimental system has the following basic parameters: hopping rate-1000 hop/s; data rate-1000 bit/s; modulation-noncoherent binary FSK; and the system uses 128 channels over a total bandwidth of 256 kHz. Because of jamming in a military network, it is necessary to introduce error control coding to get a good performance. Error correcting codes that are effective at high bit error rates need to be used. Performance results for block codes and convolutional codes are given.
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