Patent ID: 7020116

Claim:
A data transmission apparatus for transmitting an orthogonal frequency division multiplexed (OFDM) signal, in which a null symbol and a synchronous symbol are included, comprising: a transmitter for transmitting an OFDM signal; and a receiver for receiving the OFDM signal, said receiver including: an A/D conversion unit, to which said OFDM signal is applied, for converting said OFDM signal to a reception sample value sequence signal; a null symbol detection unit for detecting a position of said null symbol from said reception sample value sequence signal; a correlation arithmetic operation unit for carrying out an arithmetic operation of the correlation in order to detect a cross-correlation value between said reception sample value sequence signal containing at least a principle wave and a reflected wave which have been received and a predetermined synchronous symbol signal in a predetermined time window provided in accordance with said position of said null symbol, and obtaining cross-correlation peaks in said principle wave and said reflected wave in a comparison of said cross-correlation value with a predetermined value; an interference discrimination unit coupled with said correlation arithmetic operation unit, for detecting which peak is a less inter-symbol interference in said cross-correlation peaks obtained from said principle wave and said reflected wave; an effective correlation position detection unit for detecting a position of said detected cross-correlation peak from said interference discrimination unit; a clock generator for generating a sampling clock, said sampling clock being compensated on the bases of the position of said cross-correlation peak from said effective correlation position detection unit, and said compensated sampling clock is applied to said A/D conversion unit; and a demodulation processing unit for demodulating said reception sample value sequence signal from said A/D conversion unit.