Research On Moving Target Detecting Of Cognitive Radar Based On Transmitting And Receiving Optimization Design

Cognitive Radar(Cognitive Radar,CR)is a new Radar system,which has the ability of learning,understanding,and deducing the environment,also has the ability of a continuous feedback between the transmitter and receiver and the ability of adaptive waveform transmit.Adaptive transmitter,adaptive receiver and the target environment constitute the dynamic system structure of cognitive radar.Firstly,this paper has studied the knowledge aid and expert reasoning module of cognitive radar,has analyzed the characteristics of environment,and has researched the amplitude distribution model of sea clutter and doppler spectrum model;then this paper applies cognitive radar to moving target detecting radar and space-time adaptive processing airborne radar,and aiming at the important transmitting and receiving adaptive module,put forward the optimization algorithm of cognitive transmit and cognitive receive;finally,the simulation shows that adaptive waveform transmit and adaptive receive can effectively improve SCNR of the received signal and the detection performance of the target.The main work of this paper is as follows:(1)We analyze the amplitude distribution and doppler spectra feature of sea in detail,which is also analyzed though making using of IPIX radar measured sea clutter data,and respectively in low and high sea condition data,we fit simulation model of amplitude distribution and doppler spectra,which is cognitive radar clutter environment model of moving target detection as subsequent.(2)We consider SCNR as optimization design criterion,establish MTD radar model based on slow-time domain pulse coding,conduct a series of simplified processing aiming at the model,and get a new problem of cone constrained quadratic programming;we propose simplified gradient method coding algorithm;finally,we compare with the existed CoRe and CADCODE algorithm.The simulation results show that slow time domain code optimization can effectively improve SCNR about 3dB of radar echo,and the algorithm features small computational complexity and good real-time performance.(3)We establish a cognitive receive MTD filter group of signal model,and make use of Lagrange dual algorithm to get the optimal solution.We compare the cognitive receive MTD filter group with existed two kinds of adaptive MTD filter group,the simulation results show that the cognitive receive MTD filter group features deep notch and low sidelobe power;we use IPIX sea clutter real data to design the cognitive receive MTD filter group,the SCNR of the filter output is higher about 10 dB than that of traditional FFT filter group,which is significantly inhibitory effect of sea clutter.(4)We establish STAP inter-pulse coding signal model,slow-time code is optimized according to the selected area on spatial-frequency and doppler frequency plane to improve the performance of target detection.The corresponding optimization algorithm uses an auxiliary variable to change the optimization objective into a convex form and then solve the transformed optimization problem by alternating direction method.The results show that SCNR has a certain improvement around the parallel area to the clutter ridge.We also establish optimal STAP signal receive filter model,and make use of Lagrange dual algorithm to get the optimal solution.The results show that the output signal of SCNR is higher than that of traditional adaptive filter,and the sidelobe power of the cognitive receive filter is lower than that of adaptive filter,optimization design of the filter has good performance.