An all-digital realization of a baseband DLL implemented as dynamical state estimator

The Delay-Locked-Loop (DLL) is a device that automatically adjusts a local delay-estimate to the time-delay between two versions of an incoming signal. It has been shown by Meyr [1] that in the sense of local variance this device performs as well as the Maximum Likelihood Estimator proposed earlier [2], whereas the implementation cost can be considerably reduced. This contribution deals with a baseband type of the DLL, which was developed for non-contact speed measurement by means of two signals generated by spatially separated infrared sensors. To obtain an unbiased estimate under meaningful signal assumptions, a dynamical state estimator for the above mentioned quantities was included. We present an all digital implementation of the device with a novel numerical controled oscillator that allows to match the loop to a very wide range of the sampling rate by gain scheduling.