The Research Of Radar IF Digital Signal Processing And Dynamic Range

With the rapid growth of China's national economy and internal and external trade volume increasing, shipping becomes more and more prosperous. Marine radar system is one of the main techniques of the target detection at sea, in the modern radar receivers, in order to detect the correct target, high dynamic range is very important.Modern radar receiver requires achieving a wide bandwidth, high sensitivity and resolution, wide dynamic range, digital signal processing and multi-processing capabilities to complete the work of the radar signal reception. Dynamic range and sensitivity are the key characters of broadband digital receiver. Over sampling and gain control are possible methods to solve the problem of large dynamic range for wideband digital IF receiver, and they can improve the receiver's capabilities to detect small signals. Gain control can increase the dynamic range of the receiver, and to prevent strong signals cause overload. This thesis, depriving from the basic Sci & Tech researching project of "the research of digital processing method of intermediate frequency signal for marine radar" supported by the Ministry of Communication, is mainly researching on the processing method of improving the digital receiver dynamic range of intermediate frequency signal.First, it introduces a variety definition of radar receiver dynamic range, the linear dynamic range, gain controlled dynamic range and spurious free dynamic range (SFDR), etc. This paper mainly introduces the three different definitions of dynamic range. Also in this paper introduces several representations of dynamic range and proposes several techniques to improve dynamic range.Then, it introduces the applications of the IF sampling in radar signal processing, and the over sampling and noise shaping techniques and FFT to improve the receiver dynamic range technology. The corresponded parameters for the dynamic range improvement are analyzed. The traditional methods of increasing the dynamic range of the receivers, such as Sensitivity Time Control (STC), Automatic Gain Control (AGC), and band-pass Intermediate Frequency (IF) limiting, are researched. It is pointed out the limitation of the traditional technologies in increasing the dynamic range in wideband digital receiver.Finally, this thesis, based on the DSP of SDZ605 SAIDI radar signal sampling and processing platform, designed the method of over-sampling processing.The main research results can not only be directly applied to improve the dynamic range of the radar receiver, but also have a certain theoretical and practical significance for the future research of radar IF receiver.