Design And Simulation Of Wideband Digital Array Radar Test System

The appearance of digital array radar(DAR) makes the design of conventional phased array radar systems into the digital age. The direct digitalization of radio frequency(RF) analog signal increases the stability of a system. However, more requirements are proposed for the digital signal processing ability. Given the fact that the design of the multi-channel DAR has high data rate, great computational amount, and relative complex deign of algorithms, the paper mainly focus on the key issues in the design of DAR systems, including the analysis and design of the RF sampling technique, the design of the broadband constant beamwidth beamformer based on convex optimization and the analysis on the equalization for broadband DAR, and the design of the general signal processing platform for the broadband DAR. The feasibility and effectiveness of relevant technology are verified by MATLAB simulations and measured data analysis.The significance and background of the development of broadband DAR were described firstly in this paper. Based on the modular design concepts, the broadband DAR system was divided into a number of independent and complete functional modules, including antenna RF front-end, digital array module(DAM), broadband digital beamforming, conventional signal detection and terminal display. The key technology of each module was further analyzed. Besides, the system parameters and waveform selection of the broadband DAR were studied from the aspect of the detecting range, the radiation pattern and the ambiguity function theory.The hardware and software design of the direct broadband RF sampling of P band was analyzed. And it highlighted the theoretical measure and the practical design method of the performance of the analog to digital converter. The requirements of RF sampling on ADC performance were analyzed from four aspects: the sampling rate, the signal to noise ratio, the effective conversion level and the dynamic range. Furthermore, it introduced the hardware design of the RF sampling, including hardware platform structure, field programmable gate array(FPGA) chip selection, high speed ADC chip, and ADC front-end design. Based on the JESD2048 protocol, the FPGA realization of RF sampling was designed, which solves the problem of synchronization between multiple ADC chips. Analysis of the measured data of a real radar on the signal to noise ratio of the measured noise method and the injected signal method were also given.In view of the problem of spatial and temporal dispersion of broadband digital beamforming, the design of constant beamwidth beamforming based on convex optimization was proposed. Different from the existing design methods, this paper used a frequency point in the system bandwidth as the reference point, and by introducing the harmonic factor, the optimal design problem with the convex combination of the minimum mean square error(MMSE) and Minmax criterion on the sidelobe level was constructed. Simulation analysis verifies the effectiveness of the design. Besides, the effect of broadband channel mismatch on pulse compression was analyzed with linear frequency modulation(LFM) signal, and the performance of the frequency-domain least square(LS) equalization algorithm was further analyzed.Finally, the design of general signal processing platform was analyzed. For the requirements of the modern radar system: generality, standardization, modularization and digitization, design requirements of the general signal processing platform was put forward. Research on the standard transmission protocols was carried out, including c PCI standards, VPX standards, PCIe, Rapid IO, GTX Rocket IO transmission, fiber, and Ethernet. Based on the standard protocols above, the general hardware platform design ideas and specifications for the broadband DAR system were given, and the topology of data transmission was presented. Combined with a specific broadband DAR system, we analyzed the transmission bandwidth requirements. In addition, the computational amount of some conventional detection algorithm were analyzed from the perspective of engineering design.