Patent ID: 7499485

Claim:
A method for detecting a data-bit boundary in a satellite data stream in a pulse train of a global positioning satellite (GPS) signal, the pulse train being a product of the satellite data stream and a Pseudo-Noise (PN) code sequence, comprising: (a) calculating a correlation integral between the pulse train and a replica Pseudo-Noise (RPN) code to sequentially output M first correlation integral values and M second correlation integral values; (b) comparing the K-th first correlation integral value with the K-1-th first correlation integral value, to change the K-th first correlation integral value; (c) comparing the K-th second correlation integral value with the K-1-th second correlation integer value to change the K-th second correlation integer value; (d) calculating the sum of the changed K-th first correlation integral value and the changed K-th second correlation integral value; (e) generating a K-th variation value according to the calculated sum; repeating steps (b) through (e) while K is sequentially incremented from 2 to M; and detecting a data-bit boundary based on the variation values.