A frequency-hopped Ungerboeck-encoded 4-ary DPSK modem

The authors discuss the design of a frequency-hopped Ungerboeck-encoded 4-ary DPSK HF modem. First, they present a general channel model. Next, they present channel simulation results for rate-2/3 encoding of 8-ary and 4-ary differentially coherent DPSK. Both additive Gaussian white noise and Rayleigh fading channels are examined. The basic structure of the frequency-hopped waveform is elucidated, and it is shown how the Ungerboeck encoding is combined with the waveform to produce the frequency-hopped encoded modulation.<
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