Frequency Source Of The X-band Frequency Agile Radar Target Simulator Is Developed

In recent years, radar techniques have experienced rapid development. The radar target simulator provides a feasible way for the system performance analysis and the algorithm performance evaluation. With the increasing complexity of modern radar functions, the frequency source of radar target simulator that has coherent, high frequency, wide band, fast frequency switching, small step, low phase noise, low spurious, is required. So the design of a high-performance and multi-mode frequency source is one of key technologies in the radar target simulator.The general research situation of the radar simulator and frequency synthesizer technology is summarized firstly in this paper, then elaborate the phase noise and spur of the direct digital synthesis and phase locked loop, which provide a theoretical basis for the subject. Secondly, a frequency source program of millimeter-wave radar target simulator is proposed under the subject requirements, which is based on direct digital synthesis and field programmable gate array. And design the key cell circuit, the feasibility of this system program has been proved by the test result. Finally, some measures to improve the disadvantage have been provided.The X-band synthesizer is realized by taking full advantages of DDS, PLL, FPGA, and good frequency programming. The part of system control is developed by adopting the top-down design way. The floating-point multiplication is equivalent to multiplication of fixed point by transforming the DDS instruction words formula. The X-band synthesizer has the feature of fast frequency switching at 10 KHz resolution and 500 MHz bandwidth, its linearly frequency modulated signal bandwidth can large-scale controlled by the step of 25 Hz and the time by the step of 10 ns. The switching time is 900 ns. The measured phase noise is less than -91 dBc/Hz@1KHz, the most of spurs are less than -68 dBc.