Rapid acquiring method suitable for GPS (Global Positioning System) weak signal

Abstract

The invention discloses a rapid acquiring method suitable for a GPS (Global Positioning System) weak signal. The rapid acquiring method comprises the following steps of (1) taking a section of data of an Mms intermediate frequency signal, wherein M is larger than 1 and is less than or equal to 10; dividing the section of the data in a plurality of 1ms data, carrying out coherent integration by applying a frequency domain circular correlation method based on FFT (Fast Fourier Transform), carrying out incoherent accumulation for every result, and obtaining the primary frequency of the intermediate frequency signal and a pseudo code initial phase; (2) stripping pseudo code information in the intermediate frequency data by multiplying a section of intermediate frequency data which is additionally used with the pseudo code initial phase obtained in step (1); and (3) setting 21 to-be-acquired frequencies within a frequency shifting range [-500Hz, 500Hz] according to the primary frequency obtained in step (1), carrying out time domain sliding acquisition, and obtaining a carrier frequency with the accuracy being 50Hz. The rapid acquiring method disclosed by the invention has the advantages that the acquiring speed is rapid, the acquiring accuracy is high, the operating amount is less, the carried frequency error can be controlled within 25Hz, and the treating efficiency of a follow-up circuit is greatly increased.

Description

technical field [0001] The invention relates to the field of GPS signal processing, in particular to a fast acquisition method suitable for weak GPS signals. Background technique [0002] The Global Positioning System is a satellite navigation system jointly developed by the three armies of the US Department of Defense in the 1970s. The full English name is "Navigation Satellite Timing And Ranging / Global Positioning System", referred to as GPS system. It is a satellite-based radio navigation system with global, omnipotent (marine, land, aviation and aerospace), all-weather continuity and real-time navigation positioning and timing functions, and provides precise coordinates, Services such as speed and timing. It is the most mature and practical satellite navigation and positioning system in the current technology. At present, the GPS system has been widely used in many fields such as traffic management, topographic survey, field exploration, and navigation. To use the GPS ...

AI Technical Summary

Problems solved by technology

The advantage of the time domain sliding method is that the structure is clear and simple, and it is easy to implement. The disadvantage is that the calculation amount is huge and the processing speed is slow; while the FFT-based circular correlation method can significantly reduce the calculation amount and improve the capture speed, but the accuracy of the capture frequency is different from the data used. Length-dependent, the higher the accuracy, the longer the required data. As the data grow

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