OFDM (ORTHOGONALE FREQUENZMULTIPLEXIERUNG)-EMPFÄNGER

摘要

An intermediate frequency signal of an OFDM signal received by a tuner (2) is multiplied by a carrier wave by a multiplier (3) and a multiplier (4) to thereby generate an OFDM signal in a base band. The OFDM signal in the base band is FFT processed by an FFT circuit (5) and a resultant signal is outputted to a dividing circuit (10) and a pilot signal extracting circuit (8) in an equalizing circuit (13). A pilot signal extracted by the pilot signal extracting circuit (8) is supplied to an interpolating filter (9) and subjected to an interpolating process. An amplitude component and a phase component in the pilot signal are supplied to the dividing circuit (10). The dividing circuit (10) divides the signal input from the FFT circuit (5) by the amplitude and phase supplied from the interpolating filter (9) and a resultant signal is output to a demapping circuit (11). An FFT window circuit (6) detects the length of the guard interval from outputs of the multipliers (3) and (4) and outputs the detection signal to a control circuit (21). The control circuit (21) controls the band width of the interpolating filter (9) in accordance with the length of the input guard interval, thereby suppressing deterioration in the equalizing characteristics by noises.