GPS (global position system) signal high-speed capturing device and method

Abstract

The invention discloses a GPS (global positioning system) signal high-speed capturing device and method, belonging to the technical field of the satellite positioning and navigation. The matched filtering theory is adopted by a GPS receiver to capture the C / A code to complete related despreading algorithm at high speed in real time, and a sliding correlator is adopted to realize the tracking of the C / A code according to a matched filter. The I and Q baseband signals are synthesized before matched filtering, the influence of phase deviation is eliminated, the problem that I / Q matched filtering is needed to realize direct sequence spread spectrum signal capture by adopting the matched filtering in the prior art is overcome, and a great quantity of hardware resources is saved; and meanwhile, spread spectrum code synchronizing information is ensured to be obtained in a code element cycle, the capturing speed is increased, the production cost of the device is reduced, and simultaneously, the usability of a GPS wireless terminal is enhanced.

Description

technical field [0001] The invention relates to satellite positioning and navigation technology, in particular to a device and method for high-speed acquisition of GPS (Global Positioning System, Global Positioning System) signals. Background technique [0002] At present, there are mainly four communication systems that can provide precise satellite positioning and navigation in the world, namely GPS in the United States, GLONASS in Russia, GALILEO in Europe and Beidou positioning system in China, but the GPS in the United States is still the most widely used . [0003] The principle of GPS is very simple. The GPS receiver in the GPS wireless terminal (or GPS navigator) decodes the received satellite signals, and obtains the satellite star map orbit information and high-precision time information carried by the carrier signal. , through the formula: distance = time × speed, supplemented by the principle of four-point positioning, the user's position can be determined. [...

AI Technical Summary

Problems solved by technology

[0007] Using the code capture scheme in the frequency domain can achieve fast capture of the C / A code, but requires multiple FFT and IFFT transformations, the operation is more complex and the hardware overhead is larger

For conventional GPS wireless terminals, to complete code acquisition in the time domain, a sliding correlator is used, which consumes less computing resources, but requires multiple correlation operations, each time in a possible Doppler (Doppler Le) frequency to search for a possible code phase, the C / A code length is 1023, and the Doppler frequency range of GPS is ±5kHz. Since half a code chip is slid each time, the code phase search step is a maximum of 2046 times. For each search The code phase can be increased by half a chip, or the frequency can be increased by 500Hz. The result must be that the acquisition time is proportional to the product of the time required for the code phase search step and the carrier frequency search step, so there is still a long time required for code acquisition lack of

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