GPS frequency tracking method, device and GPS receiver

Abstract

The invention provides a GPS frequency tracking method, device and GPS receiver. The method comprises: integrating the signal after the despreading process; taking L integral lengths and recording them as L points, performing M point fast Fourier transform to obtain the M point fast Fourier transform spectrogram; The complex numbers in the spectrogram of the fast Fourier transform take the modulus value respectively and the square becomes a real number; repeat the fast Fourier transform K times, and the real numbers of the same frequency in the spectrogram after the M-point fast Fourier transform Carry out non-coherent accumulation; divide the result of the non-coherent accumulation into an outer loop and an inner loop to calculate a frequency offset value; filter and determine the inner loop frequency offset value and the outer loop frequency offset value; through digital control The oscillator generates the corresponding sine and cosine waveforms and sends them to the intermediate frequency sampling signal for mixing to eliminate frequency deviation. The invention enables the GPS receiver to still obtain relatively accurate frequency offset values ​​when there is a sudden large frequency offset, thereby improving the stability of the GPS receiver.

Description

technical field [0001] The invention relates to the technical field of GPS (Global Positioning System), in particular to a GPS frequency tracking method, device and GPS receiver. Background technique [0002] The navigation and positioning signals sent by GPS satellites are an information resource that can be shared by countless users. For land, ocean and space users, GPS receivers can receive, track, transform and measure GPS signals, so as to know the longitude, latitude and altitude (or similar measurement information) of their own locations. [0003] Among them, the design of the carrier tracking loop is a very important link in the GPS receiver, and its performance directly affects the sensitivity of the GPS receiver. [0004] The existing carrier tracking loop mainly adopts such as figure 1 In the manner shown, the GPS receiver completes the capture of the signal and obtains the intermediate frequency sampling data after the digital-to-analog conversion, and despread...

AI Technical Summary

Problems solved by technology

[0011] When the GPS receiver has a high dynamic scene or the short-term stability of the GPS receiver's clock source is affected by external environmental factors, the signal received by the GPS receiver will have a large frequency deviation. At this time, the GPS carrier tracking The loop needs a longer integration time to ensure the signal-to-noise ratio, so as to correct this large frequency offset. However, when the integration time of the GPS carrier tracking loop becomes longer, the positive and negative offsets of the integrated sine and cosine signals will occur. situation, resulting in an error in frequency offset calculation, which eventually leads to the inability of the GPS receiver to complete the positioning

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