Research On Symmetrical Triangular LFMCW Radar

LFMCW radar, with its LPI characteristic and greater advantage over monopulse radar in the ambiguity of range and velocity coupling, has always been an important topic in the radar research field. The theoretic analysis and industrial implementation of symmetrical triangular LFMCW radar form the major content of this paper.In the first part of this paper, an overview of the basic conception and constitution of LFMCW radar is presented, on base of which the working principle of symmetrical triangular LFMCW radar is explained, and the practicability of obtaining the range and velocity of the target with the partner algorithm in frequency domain is analyzed, with a brief introduction of the principle of the partner algorithm in frequency domain. The influence of time length and beat frequency on radar range is discussed. Through the analysis of ambiguity function of symmetrical triangular LFMCW signal and the single-slope LFMCW signal ,it is indicated that using the symmetrical triangular LFMCW signal can enhance the resolution ,and, using the partner algorithm in frequency domain means, the range-velocity coupling can be eliminated in the processing of target data, so that the examination and parameter estimation of moving targets in the multi-target environments can be achieved.Based on the above-mentioned analysis, this paper accomplishes the development of X-band continuous-wave radar using symmetrical triangular LFMCW signal, presenting a brief introduction of the transceiver circuit, a detailed designing and theoretical basis of DDS selection and sensitivity frequency control, as well as a devising elucidation of digital signal processing software and hardware, along with the frames of related arithmetic, the flow-chart of the programs and the illustration of key circuits.At the end of this paper, by concluding the experiments, certain disadvantages of FMCW are probed into, such as the mismatching problems in the partner algorithm in frequency domain and moving target identification. Some improvement methods have been proposed: using binary tester to reduce mismatching errors, and using two-dimensional FFT technique to promote the efficiency of moving target identification.