Doppler tolerant modified P4 code (DTMP4 code) for pulse compression radar

Abstract

Pulse compression refers to the design of a radar waveform, i.e. a “pulse compressed waveform”, so that its matched Alter response or, equivalently, its autocorrelation function (ACF), has a narrow main lobe. The narrow ACF lobe enhances the ability to resolve between closely spaced targets, i.e. good range resolution, without relying entirely on narrow pulse widths, which, at a fixed pulse amplitude, lowers the pulse energy and degrades the detection range. The appearance of sidelobes in the ACF that mask targets with low return signal power presents a challenge in the design of pulse compression waveforms. Additionally, the Doppler tolerance of pulse compression waveforms need to be examined. That is, the behavior of the sidelobe level (SLL) should be kept low to preserve good range resolution even as the velocity of the target increases. In this paper, a new pulse compression waveform called Doppler Tolerant Modified P4 Code (DTMP4 Code) is presented and analyzed. The waveform can be generated by modulating a pulse using linear frequency modulation (LFM) then applying phase coding (P4 Code) to the resulting waveform. Simulation results shows that the proposed waveform has lower average SLL than the LFM and P4 code. In addition, it is less affected by Doppler shift compared to the P4 Code.