Method for tracking satellite signal by gps

A method for tracking a satellite signal by a global positioning system (GPS), comprising:

• continuously receiving a plurality of data from one of a plurality of satellites, comprising:
• Step 1:
• retrieving a phase difference of each of the plurality of data;
• Step 2:
• calculating an average phase difference of the plurality of calculated phase differences;
• Step 3:
• calculating a frequency difference by using the calculated average phase difference and a frequency constant;
• and
• Step 4:
• calculating a new tracking frequency by using the calculated frequency difference and a tracking frequency of a last data among the plurality of received data;
• receiving a subsequent plurality of data from the satellite at the new tracking frequency, and interpreting a plurality of phase inversion points of the plurality of received data;
• calculating a time difference between each two adjacent phase inversion points among the plurality of phase inversion points;
• determining whether each time difference is an integral multiple of 20 ms;
• and
• retrieving 1-bit data for every 20 ms from the plurality of data by taking a first phase inversion point among the plurality of interpreted phase inversion points as a starting point, when each time difference is an integral multiple of 20 ms.