| 摘要 |
<P>PROBLEM TO BE SOLVED: To measure with high precision a delay profile in a communication system of an OFDM modulation scheme. <P>SOLUTION: In a delay profile measurement system, a sample enlarging part 211 adds a plurality of zero value samples to a sample row of SP (scattered pilot) signals. An IFFT 212 performs inverse Fourier transform to the enlarged SP signals to output a transmission path impulse response. A maximum level detector 213 detects the maximum power level and its position in the impulse response. A parallel shifter 214 shifts the impulse response by the amount of the difference between the position of the maximum power level and an ideal position where a direct wave appears. A D/U ratio calculator 215 detects the power level of the shifted impulse response at the time other than a time zero to calculate a D/U ratio compared with the maximum power level. Since the time resolution of the IFFT can be enhanced by the enlarged number of samples, it is possible to reduce influences caused by the phase rotation distortion of the SP signal caused by an internal factor of a digital demodulator 10. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
