Doppler detection capable good polyphase code sets based on Piecewise Linear FM

Abstract

In this paper, pieces of P3/P4 polyphase codes are used to design new classes of Doppler detection capable polyphase code sets, motivated by the phase history of a modified version of the Piecewise Linear FM code sets. The receiver is modeled as a matched filter which is decomposed into two pieces. The decomposition of the matched filter helps extract information regarding the radial direction of the target in addition to its radial speed. The code sets are shown to possess good correlation properties and Doppler properties. A subclass of the proposed code sets is converted to quadphase (via quantizing the phase terms by rounding them off to the nearest multiple of π/2) and is compared to existing quadphase code sets, one of which is simulated for comparison in this paper. The simulations show that the proposed code sets possess good correlation properties, comparable to existing code sets but stand out in being the only ones that can both tolerate and detect Doppler shifts.