ORTHOGONAL FREQUENCY DIVISION MULTIPLEX DEMODULATOR AND ITS METHOD

摘要

PROBLEM TO BE SOLVED: To provide a null symbol detection circuit that can accurately detect a null symbol for synchronization even if there is of fluctuation in transmission channels. SOLUTION: An OFDM demodulator that demodulates an OFDM modulation signal, that is transmitted while a null symbol synchronously with a frame signal, is inserted to a head of the frame signal consisting of symbols, is provided with a means 17 that detects null level, a means 19 that discriminates a pulse width, an out-band component extract means 18 that extracts information of a discontinuous part between the symbols of the OFDM modulation signal, a means 21 that generates a symbol pulse, a symbol pulse monitor means 22 that monitors the symbol pulse to output its result, and a means 23 that outputs a null symbol signal to control a frame synchronizing signal.