| The technology locating air target based on communication instruction acquires the information of angle and range and realizes precise locating and tracking through the communication instruction transmitted by the air target. It can improve signal_noise ratio received and performance of locating and tracking obviously because of only one-way power loss.The direct sequence spread spectrum (dsss) is used in the communication between radar and air target in order to improve signal_noise ratio, reduce the bit error, and achieve secret communication. This paper focuses on two aspects:the implementation of measuring and tracking in phase_coded radar using the received reply pulse responding to the request pulse transmitted by radar and the communication between radar and air target using dsss.The paper first describes the operation processes of the system and gives the integrated design block diagrams of radar and answering equipment of air target. Then the technology of dsss is analyzed. After that, the request pulse waveform design and up communication pulse waveform design are discussed in detail. Also, correlation parameters of waveforms transmitted by radar and air target are analyzed followed by the comparison of two common methods of angle tracking. They are conical scan and monopulse. After that, the model of signal transmitted and received by radar and target are generated. Following that, discuss signal and data processing of radar and target, emphasizing on CFAR, amplitude comparison monopulse and correlation despreading. Then, simulate the commutation system of dsss using m sequence as spread encoding,2DPSK modulation, differential coherent demodulation. Finally, simulate the signal and data processing by MATLAB, compare the track acquired by signal and data processing with the real track of the target, and count the bit error rate. Correctness of the method for signal and data processing is proved by the simulation result. |
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