Study On Coherence-synthetic And Design Of Display Control System For Distributed Aperture VHF Radar

The traditional VHF radar has the disadvantages of large size, high cost, and less flexibility. To improve its accuracy and mobility, a distributed VHF digital array radar system is designed, which ultilizes several distributed small VHF array radar to coherently synthesize large array aperture. This radar system is designed by all-digital technique with rich functions and a strong expansibilty, indicating its broad development prospects. This paper mainly focuses on the coherence technique and the software design of display terminal for the distributed VHF radar.Firstly, the structure and working mode of experimental system for the distributed VHF radar is introduced. Then relevant techniques of distributed coherent radar are discussed, followed by methods for parameter estimation. To realize coherence, an orthogonal waveform is transmitted for precise estimation of coherent parameter. In order to improve the precision of coherent parameter, the stepped frequency modulation signal is adopted to obtain a high estimation precision, combined with its features of multiple-pulse, orthogonality and wideband. Then the high resolution feature of this signal is analyzed, followed by the workflow of signal processing in the designed radar. The modeling and simulation are implemented with two radars. The experiment results show that 6d B SNR gain can be obtained in the coherent receiving mode and 9d B SNR gain in the coherent transmitting and receiving mode. Meanwhile, the precision requirement for parameter estimation of transmitting coherence is analyzed.Finally, the display and control system of the distributed VHF radar are presented. The implementation for each module of this system is introduced in details. As a human-computer interface, this system has two main functions. One is that it takes the input of system operation parameters in the control interface and sends them to the timing control board as a protocol. The other one is that it can control system correction and then display and export the correction result and the target track information. The correctness of the system is validated by test experiments. After the trial with each module of the radar system in different operation modes, it is confirmed that the system can correctly transmit and receive signals in search mode. In the correction mode, the channel phase error is within ±5oafter correction. Besides, it is shown that the system can generate correct waveforms according to the input parameters in the simulated target mode.