Adaptive delay tracking with a delay-lock estimator

The aim of this work is to present a delay lock estimator based on the use of a variable delay line. This line stores samples taken and shifted at non-equal intervals controlled by a variable frequency oscillator (VFO). When the VFO frequency is increased the equivalent delay is decreased and vice-versa. A differential cross correlator used with a second order loop filter allows the system to track continuously variable delays. An adaptive inverse filter can be used to reduce the influence of strong narrow band energy on the estimator.