Optimized lattice-form adaptive line enhancer for a sinusoidal signal in broad-band noise

An adaptive filter configuration, known as the adaptive line enhancer (ALE), has previously been suggested by Widrow et al for the detection of sinusoidal signals in wide-band noise. Some refinements of the ALE are suggested in this paper. First, for the special case of a single sinusoid, it is shown that there exists an optimum value of the so-called decorrelation parameter, which in earlier studies seems always to have been chosen equal to unity. Second, a lattice filter implementation of the general ALE is derived and turns out to be somewhat different from those suggested in the literature. Simulations are used to examine the behavior of the suggested schemes. The results show substantial improvements in the estimate of the unknown sinusoidal frequency, both with respect to bias and accuracy.