| 摘要 |
PURPOSE: An apparatus for detecting a frame starting point of a frequency hopping(FH)/orthogonal frequency division multiplexing(OFDM) communications system is provided to make a transmitter transmit data frames inserting synchronous symbols designating synchronous patterns, and to make a receiver detect the synchronous patterns of the synchronous symbols, so as to exactly detect the frame starting point without an energy arithmetic operation. CONSTITUTION: A frequency hopping(FH)/orthogonal frequency division multiplexing(OFDM) data frame inputted to a frame detector(300) is inputted to a correlator(310). The correlator(310) detects a synchronous symbol of the FH/OFDM data frame, and detects synchronous patterns of predetermined bits of the synchronous symbols, then calculates correlations of the synchronous patterns to output the calculated correlations to a correlation detector(320). A threshold comparator(325) inputs the correlations to detect the correlations as valid correlations, only when correlations under a low threshold value and over a high threshold value are detected, and performs a data demodulation. A guard interval remover(330) removes a guard interval inserted into a frame transmitted from a transmitter, and outputs a data frame starting point to a serial to parallel(S/P) converter(340). The S/P converter(340) converts data of the guard interval remover(330) in parallel, and outputs the parallel data to a fast Fourier transform(FFT) block(350). The FFT block(350) applies an FFT to the parallel data to calculate phases and amplitudes of each carrier frequency component, and outputs the parallel data to a parallel to serial(P/S) converter(360). The P/S converter(360) converts the parallel data in serial to output the serial data to a signal demodulator(370). The signal demodulator(370) inputs the serial data to demodulate the serial data to original data, then outputs the original data. |
