Signal receiver and method for estimating residual doppler frequencies of signals thereof

Abstract

The invention provides a signal receiver. The signal receiver comprises a carrier removal module, a Fast Fourier Transformation (FFT) module, and a signal processor. The carrier removal module generates a carrier signal with a frequency of an estimated carrier frequency, generates at least one delta carrier signal with a frequency of the carrier frequency plus a delta frequency, removes the carrier signal from a first signal to obtain a second signal, and removes the delta carrier signal from the first signal to obtain a third signal. The FFT module derives a series of first FFT values from the second signal, and derives a series of second FFT values from the third signal. The signal processor estimates the carrier frequency of the second signal to obtain the estimated carrier frequency, determines the delta frequency for the carrier removal module, estimates a residual Doppler frequency of the second signal according to both the first FFT values and the second FFT values, and adjusts the estimated carrier frequency according to the residual Doppler frequency.