Methods Of Improving The Precision Of Height Measurement In LFMCW Radar Altimeter

LFMCW radar altimeter was widely used in civil and military filed, such as measuring airplane height, control bomb-dropping, low altitude navigation, Error of measuring height in the part of digital signal processing include fixed error restricted by the bandwidth of signal and error of estimating frequency restricted by the frequency interval in FFT. So in some situations required high precision, it does not satisfy requirement by using direct FFT to estimate the spectrum.This paper analyzed the spectrum of LFMCW Radar minus-frequency signal under the environment of point-target and cover-target. In the first environment we can improve the precision of measuring spectrum using several methods of frequency subdivision. In the behind environment, because spectrum of minus-frequency signal became wider we need gain the lowest height through adopting technology of forward edge of spectrum detected. At lastα-βfilter is imposed to height tracing so as to accomplish measuring frequency and height accurately base on the relativity of two closed value measured.Finally we designed and simulated the system of radar altimeter base on the methods of LFMCW radar signal process and practical requirement of certain LFMCW radar system. This system can improved precision of measuring height by decreasing error of estimating frequency on the base of fixed bandwidth.