ADAPTIVE LINE ENHANCERS WITH DISCRIMINATED STRUCTURES

The adaptive line enhancer eliminates noise from a sinusoidal signal w ith the unknown frequency buried in the noise and extracts the sinusoi dal signal. The performance of the adaptive line enhancer is represent ed by the signal-to-noise improvement figure. The signal-to-noise impr ovement figure increases as the bandwidth of the adaptive line enhance r is made narrower. The conventional adaptive line enhancer, however, contains an incompatible problem in that the convergence of the adapti ve coefficient is deteriorated when the signal-to-noise improvement fi gure is raised by narrowing the bandwidth. This paper proposes the ada ptive line enhancer with the discriminated structure to solve this pro blem. The adaptive line enhancer with the discriminated structure is c omposed of two parts. One is the (frequency) estimator that estimates the frequency of the unknown sinusoidal signal, and the other is the ( sinusoidal signal) discriminator that discriminates the unknown sinuso idal signal from the noise. The estimator is the conventional adaptive line enhancer, and the bandwidth is determined so that the convergenc e of the adaptive coefficient is the fastest. The discriminator is the narrowband bandpass filter where the center frequency is controlled b y the adaptation coefficient. This paper presents the optimal design m ethod for each of those parts, and the effectiveness of the method is verified by a computer simulation.