A Novel Rule for Designing Tri-Stages Piecewise Linear NLFM Chirp

Chirp waveform is essential to a radar system with pulse compression technique. Various Nonlinear Frequency Modulation (NLFM) chirp waveforms have been proposed to suppress sidelobes that are relatively high in the Linear Frequency Modulation (LFM) chirp waveform. One type of them is the Piecewise Linear NLFM (PWL-NLFM) that can be viewed as a concatenation of several LFM stages with a different chirp rate. The challenge in using this is figuring out the chirp rate for each stage. In this paper, a rule for determining the chirp rate for each stage value of the Tri-Stages PWL-NLFM (TS-PWL-NLFM), a particular type of PWL-NLFM, is proposed. Snippet code in GNU Octave for generating the discrete-time TS-PWL-NLFM waveform as well as for calculating the matched filtering in order to evaluate the designed chips are presented. Besides, numerical examples run show its superiority sidelobes reduction compared to the LFM and the existing results.