Adaptive instantaneous frequency estimation of sinusoidal signals using numerical differentiation

An algorithm for instantaneous estimation of sinusoidal signals basing on numerical differentiation is presented in this paper. With all parameters unknown, the signal is sampled at a fixed frequency, and central Lagrange interpolation of multi-points is employed for computation. The proposed algorithm is adaptive to any sinusoidal signal with its frequency varying from 1 Hz to 4 kHz, its amplitude varying from 0.1 V to 100 V, and its phase varying from 0 to 360. The proposed algorithm for frequency estimation needs in most 1 cycle, with an accuracy of more than 0.001%. An example for test study is simulated in Matlab software with satisfactory results.