Apparatus and method for detecting time synchronization of ofdm system and apparatus for receiving

Orthogonal frequency division time synchronizer for multiple access system will set one of the minimum sampling frequency at least four times over-sampling the signal over-sampled by a master clock, and a plurality of having a higher frequency than in the transmitting device the receiving signal to the on-time signal and outputs the remaining-over respectively by a time shift determined relative to the time signal on the sampling signal and signal on-time signal. Time alignment unit calculates a correlation value with correlation each other and the signal that is known in advance for each shift signal and on-time signal, and detecting the maximum energy value among the calculated correlation values ​​and then, the frame and compares it to a preset threshold value and it detects the start point. OFDM, the time synchronization frame, a symbol, a master clock