A Non-linear Frequency Modulation Signal Deskewing Processing Method

Abstract

The invention provides a dechirping method of a nonlinear FM signal. After frequency-mixing dechirping and low-speed A / D sampling of nonlinear and linear FM signals, frequency spectrum expansion and linear frequency modulation are carried out to recover an original echo signal, matched filtering is carried out on the recovered echo signal and an original emission reference signal to obtain a target one-dimensional distance image, and the nonlinear FM signal is dechirped. The method of the invention can be used to lower requirements for receiver A / D sampling and transmission equipment of the nonlinear FM signal, and has significant meaning in a broadband radar system.

Description

technical field [0001] The invention relates to the technical field of radar (sonar) signal processing, in particular to a non-linear frequency modulation signal deskewing processing method. Background technique [0002] Both linear frequency modulation (LFM) and nonlinear frequency modulation (NLFM) are radar (sonar) signals that use nonlinear phase modulation to obtain large time-width bandwidth products. Linear frequency modulation signals are easy to generate and can be deskewed due to their advantages And is widely used. However, the sidelobe is higher after the pulse compression of the linear frequency modulation signal. In the application, the method of windowing is usually used to suppress the sidelobe, but the window will widen the main lobe and cause the loss of signal-to-noise ratio while reducing the sidelobe. Non-linear frequency modulation (NLFM) signals do not need to use windowing to reduce sidelobes, thus avoiding the problems of signal-to-noise ratio loss ...

AI Technical Summary

Problems solved by technology

Mir H S, Wong U K T and others proposed a low-rate sampling processing method for non-linear frequency modulation (NLFM), but this method needs to know the phase function of the non-linear frequency modulation signal, and then calculate the mixed frequency at each delay time in the receiving window The phase value of the final signal, the implementation process is complex and the amount of calculation is huge (references: Mir H S, Wong U K T. Low-rate sampling technique for range–windowed radar / sonar using nonlinear frequency modulation[J].IEEE Transactions on Aerospace and Electronic Systems, 2015,51(3):1972-1979.)

[0004] In the radar system, the broadband non-linear frequency modulation signal has high requirements on the hardware implementation and the use environment. Since the increase of the signal bandwidth will bring great pressure to the detection of the receiver, at this time, the deskewing processing method can be used The linear frequency modulation signal requires a higher speed A / D converter and a higher speed data storage, which greatly limits the imaging resolution of the radar

Images