Research And Design Of RF Bandpass Sampling Radar Digital Receiver

L-Band ATC primary surveillance radar, which is an important air traffic control equipment, is to ensure flight safety of the airlines. In this sense, it is very meaningful to design high-performance digital radar receiver. Due to the limited level of the digital devices, Intermediate Frequency (IF) sampling is the main scheme of the digital radar receiver. However, analog mixer is needed in this kind of digital radar receiver and its performance is limited by the analog front end. With the rapid development of microelectronics technology, Radio Frequency (RF) bandpass sampling structure could be applied to the L-Band ATC digital radar receiver and this structure has no need of analog mixer. The RF front end is very simple so that it (?)as more reliability and stability than IF sampling structure.Firstly, the theory of digital radar receiver is introduced in this paper and the digital radar receiver based on RF sampling scheme, which includes sampling scheme, orthogonal transformation scheme, controllable frequency conversion scheme and decimation filtering scheme, is designed according to the characteristics of the narrow bandwidth and the characteristics of large carrier frequency range of one of the L-Band ATC radar signal and the scheme is also performed accordingly by MATLBA simulations. Then the digital radar receiver front end, which includes orthogonal transformation module, controllable frequency conversion module and multi-stage decimation filtering module is implemented based on the ALTERA FPGA chip EP4SGX230. Finally, the hardware design of the radar receiver and FPGA development are studied and the debugging results illustrate that the scheme of the system is feasible and the design can meet the requirements.