Fast Adaptive Detection of Sinusoidal Signals Using Variable Digital Filters and All-pass Filters

This paper proposes an adaptive line enhancer (ALE) using a variable band-pass (BP) filter and an all-pass filter. The proposed ALE has the high convergence speed and the small steady-state value of the squared error. The all-pass filter outputs the signal which consists of a sinusoidal signal which has the same phase as that of the input signal to the ALE and a white noise which has no correlation with that of the input signal to the ALE. The variable BP filter has two parameters which control its center frequency and bandwidth. In the proposed ALE, both of the center frequency and the bandwidth are adaptively adjusted using least mean squares algorithm. As the reference signal, the input signal to the ALE is adopted to adjust the center frequency and the output signal of the all-pass filter is adopted to adjust the bandwidth. Numerical examples show that the proposed ALE has the high convergence speed and the small steady-state value of the squared error.