Research On Sub-Nyquist Radar Sensing With Finite Rate Of Innovation

Traditional receiving(or sampling) and reconstruction of radar signals obey Nyquist sampling theory. With the requirements for target discrimination and spatial resolution become increasingly higher, radar receiver faces a big problem that the bandwidth of the intercepted radar signal increases rapidly. So the radar system on this basis not only requires very high sampling rate, but also is confronted with tremendous pressure and a huge waste of power consumption during real time storage and processing of the required data. For the past few years, along with the proposing and development of finite rate of innovation(FRI), one can sample a radar signal at a frequency rate far below the Nyquist sampling rate and reconstruct the original signal exactly using parametric feature of a signal, as a consequence, the sampling rate of a system is greatly reduced, so does the storage and transmission pressure of signal processing devices.By the use of its parametric characteristics, radar signal is able to be modeled as a FRI signal which can be perfect represented with finite parameters. Then, carry out the sample preprocessing for radar signal under the FRI framework, and sample the signal uniformly at a much lower frequency rate than the Nyquist rate. At last, reconstruct the original signal by means of spectrum estimation technique. This paper focuses on FRI theory, the main research contents and achievements are as follows:1.The research of FRI principles. At first FRI theory is introduced, and the whole stages of sub-sampling and constructing scheme based on FRI principles is described using mathematical language. Then, MATLAB simulation experiments are exploited to prove the feasibility of FRI technology, as well as explore the impact of many factors, such as sampling rate, sampling phase, parameters of filter etc. All of these experiments can provide a reference for the design of the sub-sampling and reconstruction physical FRI system.2.Propose a new sub-sampling structure for radar signal based on FRI principles. And analyze and compare the advantages and disadvantages as well as the feasibility between the designed structure and the existing FRI structures. MATLAB simulation experiments are exploited to explain the structure in detail.3.Design FRI experimental platform for the proposed sub-sampling structure, which includes hardware part and software part. According to the signal features, the hardware part designs analog multiplier circuit, analog low-pass filter circuit, amplifier circuit and constructs a mixing and filter module. At the same time, the hardware part realizes the generation, sampling, transmission, storage and processing of the radar signal using PXIebus instrument. At last, introduce the hierarchical relationship and program flow for the software part. The software part has a friendly interface based on Lab VIEW platform, implements waveform display, data storage, parameter setting, algorithms adjustment and other functions of the designed system.4.Experiment validation of the sub-sampling approach based on FRI principles. Conduct hardware experiments by using of this FRI sub-sampling system. Cogent experiments demonstrate the validity and feasibility of the designed sub-sampling system and the reconstruction method.