DELAY TIME CORRECTING DEVICE FOR DISCRETE FOURIER TRANSFORMATION VALUE

摘要

PURPOSE:To correct the Fourier transformation value of a delay less than one sampling period by multiplexing the Fourier transformed result of a signal to be correlated by phase correcting data shown by a specific formula to execute phase correction in a frequency area. CONSTITUTION:A Fourier transformation part 1 executes the descrete Fourier transformation of N sample values g(-DELTAt), g(tau-DELTAt) to g((N-1)tau-DELTAt) in total which are defined by setting up the sampling period of analog signals to 7 and sampling point (t) as t=-DELTAt, tau-DELTAt to ((N-1)tau-DELTAt) to obtain a frequency component G' (f)=G(f).exp (-i2pifDELTAt). A phase correction calculating part 2 calculates phase correction data gamma=exp (j2pifDELTAt) and a phase correction multiplying part 3 multiplies the G' (f) by the data gamma. Consequently a delay time can be accurately corrected even in the case of the correction of a delay time less than the sampling period tau.