A NEW TECHNIQUE FOR ADAPTIVE FREQUENCY ESTIMATION AND TRACKING

A technique is presented for estimating the frequency of a sinusoid in noise. The technique is based on a variable delay element. The authors show that the corresponding error surface is sinusoidal, and that the first maximum of the error function occurs at one half the period of the unknown sinusoid. An algorithm that is based on gradient techniques to find this maximum is developed, and from this maximum the authors directly compute the frequency estimate. The algorithm works in the time domain with a simple adaptive delay update computation. The technique has been tested in simulations with signal-to-noise ratios as low as 1:10, with excellent performance. The speed of the algorithm depends on a convergence factor that is computed from an initial estimate of the power of the input signal. Since the technique is adaptive, it can also be applied to tracking a time-varying frequency.