On Precision Measurements of Small Distance Changes in FMCW Radar Level Gauges

The paper deals with the problem of accuracy increasing of small distance changes measurements in radar level gauges with frequency modulated continuous wave signals. In the considered task advantages of estimation of time delay differences as indirect parameter of beat signals full phase are shown. This approach is shown to be more informative in comparison with traditionally applied estimators of time delay difference, which based on a frequency and initial phase estimation as separate parameters. For the model of beat signal of level FMCW radar in the typical interference conditions it is proposed to use the phase-based estimator which was investigated by us in the previous works. The obtained results shown that in the considered conditions the proposed approach allows one to reduce the variance and bias of level increments estimates by several times in comparison with traditionally used estimators.