A novel Doppler-tolerant polyphase codes for pulse compression based on hyperbolic frequency modulation

The conventional polyphase pulse compression codes including Frank code, P1, P2, P3, and P4 code suffer severe signal loss in performance under Doppler environment. This paper proposed a new polyphase pulse compression codes which are conceptually derived from the step approximation of the phase curve of the hyperbolic frequency modulated chirp signal. Comparing with the above conventional codes and the sidelobe-optimized polyphase P(n,k) code, the peak value of this new polyphase codes degrades much slower and the range solution as well as maximum sidelobe level are almost constant when Doppler frequency increases. The main disadvantage of this polyphase code is the relatively high sidelobe level without Doppler effect, which can be addressed by applying the proper window function. The desired Doppler-tolerant property of this new polyphase codes is very attractive for radars employing digital signal processing.