A method for target estimation of level radar

The structure and principle of the signal processor of a frequency modulated continuous wave (FMCW) radar which is used to measure the liquid level of the oil tanks are described. Two methods, SECF (spectrum envelope curve fitting) and SEEE (spectrum envelope edgeway estimating), are presented for the estimation of the liquid level and, these methods are compared in terms of their abilities to extract the level information from the smeared radar returns and of the level estimation accuracy. The results obtained in a field experiment show that the spectrum envelope curve fitting method is more robust and more accuracy than the SEEE method. An accuracy of better than 1/10/sup 4/ in the liquid level measurement has been achieved by means of the SECF method.