Frequency properties of an adaptive line enhancer
This paper presents the steady frequency response function (FRF) of an adaptive line enhancer (ALE) by using a z-transform method. The principle of ALE parameter selection is investigated and the physical meaning of its signal-to-noise ratio (SNR) enhancement is given clearly and directly. Simulation results show that the FRF of the ALE to simple harmonic input signals is as a tracking narrowband filter, and its phase shift at the input frequency is exactly zero. An experimental verification of the ALE frequency properties based on a digital processor board was also carried out. The results not only verify the theoretical analysis and frequency domain simulations, but also disclose that, with respect to multiple harmonic input signals, the ALE system functions as a tracking comb-like narrowband filter with zero-phase response at the input harmonic frequencies. This characteristic has potential application in phase-detection and variable-value tracking in preprocessing of unknown harmonic signals with background noise.
adaptive line enhancer frequency response function (frf) gain-phase characteristic adaptive tracking filter