| Ranging is the most essential function of radar, however, high-precision ranging, especially the short range, is an important application field of civil radar. In this thesis, based on this kind of application, we made theoretical analysis and engineering practice on high-precision LFMCW and its signal processingMillimeter wave broadband LFMCW radar has quite high theoretical range-precision and distance resolution, however, for the real radar system, the nonideal parameter of its transmitting signal, such as power fluctuation and the nonlinearity in frequency sweep, will result in the decreasing of the practical rang-precision and the distance resolution of radar.LFMCW Radar adopts the receiver with the structure of"Homodyne-Fourier", and acquires the range spectrum after its IF signal is sampled, and then processed by FTT. FTT makes the frequency sampled at a same frequency interval on unit circle, and the frequency interval limits the practical range-precision of the radar, and makes range precision at an equivalent level with range-resolution. Increasing the FFT's points can decrease the frequency interval, but it will increase the complexity of computation at large extent.In this thesis, aimed at the above-mentioned two-side problems, based on analyzing the theory of LFMCW radar ranging deeply, we implement the work of intermediate frequency signal processing. Main contents included are:1.Analyzed, simulated and validated the effect of power fluctuation and the nonlinearity in frequency sweep on radar practical ranging precision, and the validating method of nonlinearity in frequency sweep. We have realized the validating of nonlinearity in frequency sweep.2.Analyzed, simulated the effect of maximal value estimate method, coherent accumulating on ranging performance.3.Accomplished the hardware design of intermediate frequency signal processing4.Accomplished the software design of intermediate frequency signal processing. In this software realized the FFT, spectrum estimation and coherent accumulating. |
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