High resolution frequency hopped symmetric DPSK in tone jamming

Symmetric DPSK (SDPSK) is a modified form of DPSK, with data values coded as ±90° phase shifts. This modification reduces spectrum regrowth of filtered signals in nonlinear amplifiers, and sensitivity to intersymbol interference caused by filtering. On an ideal channel, SDPSK performance in optimized partial band noise (PBNJ) jamming is the same as DPSK performance under the same conditions. In traditional frequency hopping (FH) the signal jumps among a set of allowed carrier frequencies separated by the signal bandwidth. To improve resistance to tone jammers, high resolution frequency hopping (HRFH) uses many more allowed frequencies, much closer together. The probability of the signal hitting a tone does not change, but the jammer cannot control tone location relative to the signal. The authors investigate HRFH SDPSK performance in tone jamming. For easy of analysis, the effects of channel filtering and AWGN are ignored. Jamming tones have equal power, and inter-tone spacing is no less than the signal bandwidth. Communication performance is found and the tone jamming strategy optimized for this model. It is shown that multitone jamming requires 0.5 dB less power than PBNJ to effect the same degradation. Given the simplifications used, this difference is not significant