FINE FFT WINDOW POSITION RESTORATION DEVICE FOR OFDM SYSTEM RECEIVER

摘要

PROBLEM TO BE SOLVED: To prevent deterioration of system performance by correcting the phase error of a fast Fourier transform(FFT) window by making use of the zero point crossing frequency of the phase change value that is calculated between the transmitting and receiving complex value. SOLUTION: Orthognal frequency division multiple(OFDM) signals are successively inputted to an FFT device 250. A symbol start detector 230 detects a symbol start a part and applies a symbol start signal to an FFT window controller 240. The device 250 performs the FFT in response to the symbol start signal. A phase calculator 260 calculates a phase change between the complex signal value which are outputted from the device 250. A zero crossing counter 270 counts the zero point crossing frequency of the calculated phase change. Then the controller 240 calculates the error of every remaining FFT sample based on the zero point crossing frequency to correct the symbol start part and to change the FFT activation time point.