DOPPLER FREQUENCY TRANSITION COMPENSATING METHOD USING FAST FOURIER TRANSFORM

摘要

PURPOSE: A Doppler frequency transition compensating method using an FFT(Fast Fourier Transform) is provided to compare signal component powers of two frequencies adjacent to an IF(Intermediate Frequency), and to control an output frequency of a local oscillator. CONSTITUTION: After performing a frequency transition to a base band, a system detects a Doppler frequency transition. According to a detected result, the system compensates a remaining carrier wave frequency of a base band receiving signal. The system performs an FFT(Fast Fourier Transform) for the signal, and calculates a power distribution of a discrete frequency component. The system estimates a remaining carrier wave frequency error. The system reduces noises by using an LPF(Low Pass Filer). The system controls a frequency of a local oscillator, and compensates the remaining carrier wave frequency error. If errors are generated while compensating the remaining carrier wave frequency error, the system returns to a remaining carrier wave frequency compensation step or an error estimating step according to an error kind.