Patent ID: 7395155

Claim:
A correlating circuit of a Global Positioning System (GPS) receiver coupled to a data receiving register adapted to store a sample digital data as an IF data from a RF front end, comprising: a parallel C/A code generating unit, sequentially and in parallel generating a portion of total bits of a C/A code representing a satellite and sequentially outputting the portion of the total bits of the C/A code therefrom; a parallel Doppler generating unit, sequentially and in parallel generating a portion of total bits of a corrected frequency code of Doppler effect and sequentially outputting the portion of the total bits of the corrected frequency code therefrom; a multiplication unit coupled to the C/A code generating unit and the Doppler generating unit, sequentially multiplying the portion of the total bits of the C/A code from the parallel C/A code generating unit, the portion of the total bits of the corrected frequency code from the parallel Doppler generating unit, and the IF data; and a digital addition and peak detector coupled to the multiplication unit, for adding multiplications therefrom for generating a total addition value and searching a maximum in the total addition values by various offsets for the C/A code and the corrected frequency code for identifying the satellite transmitting the IF data, wherein the digital addition and peak detector comprises: a digital adder, coupled to the multiplication generating unit, adapted to adding the multiplications for generating an I addition and a Q addition; a square and radical calculator coupled, to the digital adder, adapted to receive the I and Q additions and generating a square, addition and radical value thereof; an integrator, coupled to the square and radical calculator, adapted to integrate an output therefrom during a period of time; and a peak detector, coupled to the integrator, adapted to search a maximum of the I and Q additions for identifying the satellite transmitting the IF data.