Adaptive HF for voice and data

Summary form only given. The authors describe an adaptive HF system for voice and video. The system uses information obtained from a link quality analysis and/or ionospheric soundings to determine the appropriate link and frequency over which to communicate. In addition, the system can be frequency hopped, thereby reducing the probability of being jammed. The improved performance obtained using frequency-agile modulation techniques was measured, and it is shown that the FH (frequency hopping) modem described is capable of achieving low error rates at low signal-to-noise ratio and with narrow bandwidth.<
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