DIGITAL MAXIMUM-LIKELIHOOD-ESTIMATION OF SIGNAL DELAY WITHOUT ANTIALIASING LOWPASS FILTER

The measurement of signal delay, for example in the fields of flow measurement or radar, is an estimation problem on account of the noise which is always present in the measurement system. The optimal way to solve this problem is the use of a maximum-likelihood estimator. In the case of white gaussian noise the algorithm of maximum-likelihood estimation is based on the cross-correlation of the received signal with the transmitted signal. In modern systems the received signal is sampled and quantized and the cross-correlation is implemented by digital means. In such systems an analog anti-aliasing lowpass filter has to be applied before AD-conversion. Usually, this filter is an expensive analog component. In this paper a novel algorithm for maximum-likelihood estimation is presented, which has the advantage that no anti-aliasing lowpass filter is needed. Furthermore, the relation between this novel maximum-likelihood estimator and the cross-correlation is shown.