Waveform Analysis And Design For Colocated MIMO HFGWR

Selection and parameter design of MIMO radar waveform directly determine the key radar performance such as detection range,system resolution and accuracy,and potential ability of anti-interference,etc under the specific environment.Considering practical project demand and combining advantages of MIMO system with high frequency ground wave radar(HFGWR),design works of the miniaturized and colocated MIMO-HFGWR are conducted based on theoretical analysis,waveform parameters design and verification by simulation in this paper,which contribute for the main theoretical evidence and parameter framework.Main content is summarized as follows.(1)Norton attenuation,second-order scattering coefficient of sea echo and equivalent environmental noise figure under different frequencis are considered to signal to interference and noise ratio(SINR)modelling based on range and doppler spectrum and detection ability analyzing to help choose frequency,power and duty ratio for the radar detection task.(2)Aiming at detection task of the colocated MIMO-HFGWR and target characteristic,linear frequency modulation(LFM)signals at the same bandwidth with different doppler frequency shift(DFS)are generated through phase coding in the slow time domain which are non-overlapping distributed in the Doppler spectrum and orthogonal so that a doppler devision multiple acess(DDMA)waveform set are achieved.This waveform effectively improves the utilization rate of the doppler spectrum and can reduce the risk of radio interference.(3)Analyzing the ambiguity function of DDMA-LFM waveform,the results indicate that autocorrelation is not affected by dopller frequency shift but the cross-correlation about the effective dopller spectral width that avoiding doppler velocity ambiguity changes from radar pulse repetition frequency to frequency offset difference.Combining DDMA-LFM waveform sets and transmitting antenna array to deduce the MIMO ambiguity function related to time delay-dopller frequency-spatial azimuth,simulation and analysis indicate that : range(time delay)and spatial azimuth are independent;dopller frequency and spatial azimuth interact with each other partly,but within the effective doppler spectrum the radar resolution performance is not affected;meanwhile,the mutual coupling between waveform sets and transmitting array can improve azimuth resolution to a certain extent at certain direction.(4)Signal processing procedure of DDMA-LFM radar echo is designed and corresponding simulation based on radar echo of the designed waveform parameters are conducted in matlab software.The results verify the validity and effectiveness of the waveform design and signal processing,and confirme the feasibility of DDMA-LFM orthogonality and the rationality of the parameters applied in HFGWR.