Patent ID: 7609903
Filing Date: 2009-10-27
Classification: G01S,G06F,H04B

Abstract:
1. A spread spectrum signal demodulating method comprising the steps of: performing a fast Fourier transform on a received signal having carrier wave modulated with a signal obtained by spectrum-spreading data with a spread code and storing a result of the fast Fourier transform in a first memory; reading out the result of the fast Fourier transform of the received signal stored in the first memory and a fast Fourier transform result of the spread code for storing in a second memory and multiplying the result of the first Fourier transform of the received signal and the fast Fourier transform result of the spread code to detect the correlation between the received signal and the spread code; shifting a readout address of one of the fast Fourier transform result of the received signal and the fast Fourier transform result of the spread code by an amount corresponding to a carrier frequency of the received signal, and reading the fast Fourier transform result from one of the first memory and the second memory; and performing an inverse fast Fourier transform to a result of the step of multiplying to detect a correlation point between the received signal and the spread code.