Patent ID: 7203250

Claim:
A frequency analysis method using a-power-of-two N A =2 a , where “a” is an integer, memories for discrete Fourier transform, comprising: a former-stage calculation step of taking out frequency components of an input signal having a-power-of-two N B =2 b , where “b” is an integer and b>a, data items, in a comb manner and of calculating N A intermediate data items, a latter-stage calculation step of applying fast Fourier transform to the intermediate data items obtained in the former-stage calculation step, by using the N A memories for discrete Fourier transform, and executing the former-stage calculation step and the latter-stage calculation step a predetermined number of times with the frequency components taken out in the comb manner being changed, to execute discrete Fourier transform through the predetermined number of times for determining the position of a receiver and time information of a GPS satellite.