The most important specification of the level measurement system is the accuracy . the range measurement accuracy of a fmcw radar is strongly affected by the stability and the linearity of the frequency modulation . thus the vco ' s nonlinearity correcting method is discussed 利用fft ( dft )频谱估计频率精度受fft频率量化(即谱线之间的间隔)的限制,对应的fmcw雷达的距离估计精度则受扫频带宽的限定。