The Research And Implementation Of Signal Processing Technology For FMCW Radar Ranging

With the rapid development of radar technology, the range measuring and speedmeasuring system by using frequency modulated continuous wave radar became more andmore widely used in daily life and industrial production, meanwhile each domain had higherrequirement for the accuracy of measurement. As the radar echo signal would be affected bythermal noise, ground clutter and other noise during its transmission, it would cause somemeasurement error. A comprehensive signal processing algorithm was proposed on the basisof the analysis of the characteristics of the difference frequency signal of FMCW radar andthe reasons for causing measurement error. Firstly the difference frequency signal affected bynoise was processed by an adaptive noise reduction method. Then the frequency of differencefrequency signal could be accurately estimated by frequency estimation algorithm based onFast Fourier Transform. Finally the distance and speed could be achieved according to theformula.Firstly the basic working principle of FMCW radar and the theory of range measuringand speed measuring was introduced, and the reasons for causing measurement error ofFMCW radar were analyzed. Secondly autocorrelation detection method and noise reductionalgorithm using empirical mode decomposition were carried out due to the characteristics ofthe difference frequency signal. The two methods both could be adaptive to extract the weakdifference frequency signals which submerged in noise so as to improve the signal-to-noiseratio. Thirdly as there were some problems of energy leakage and picket fence phenomenon inthe spectrum analysis of difference frequency signal of frequency modulation continuouswave radar with the FFT technique, the amplitude ratio method and energy centrobaricmethod which were two commonly used spectrum correction theory were introduced. Afrequency estimation algorithm of sine signal based on FFT coefficient was proposed on thebasis of the amplitude ratio method, and it could avoid complex modulo calculation ofcomputing the signal amplitude spectrum. An modified energy centrobaric method combinedwith adjusting the frequency offset or adjusting the truncation length were proposed on thebasis of energy centrobaric method, and it could improve the frequency estimation precision of the difference frequency signal.Finally a FMCW radar range measurement system based on LabVIEW was designed byusing radar transceiver IVS-163and MP424data acquisition card. The system can carry outthe real-time collection and analysis for the difference frequency signal, and ultimately extracttarget information. Through the whole test and experiment, the results indicate that thecomprehensive signal processing algorithms is reliable and effective.