Weak signal capturing method based on overlapping difference cycle coherent integration

Abstract

The invention provides a weak signal capturing method based on overlapping difference cycle coherent integration. The weak signal capturing method based on overlapping difference cycle coherent integration comprises the steps that firstly, a section of medium-frequency signal data lasting for 20M ms+10 ms is taken, carrier-removal processing is carried out, a Doppler frequency shift range, a searching stepped frequency and a detection threshold are set; secondly, the data after carrier-removal processing are segmented according to the length that L= 10 ms, self-overlapping processing is carried out on each data block, and FFT conversion is carried out; thirdly, FFT conversion is carried out a locally generated C / A code, a conjugate is taken and is multiplied by each result finally obtained in the step 2, and IFFT processing is carried out; fourthly, conjugate complex number multiplication is carried out each data block processed in the step 3 and the adjacent data blocks whose data are overlapped with those of the data block, then grouping correlation summation is carried out, and whether the signals are successfully captured is judged. The weak signal capturing method based on overlapping difference cycle coherent integration is applied to weak signal capturing of a single-frequency civil software receiver in a global positioning system.

Description

technical field [0001] The present invention relates to the acquisition processing method of the receiver in the Global Navigation Satellite System (GNSS—Global Navigation Satellite System), and the specific scope of application is the single-frequency civilian software receiver in the Global Positioning System (GPS—Global Positioning System) for weak The signal capture method. Background technique [0002] The global satellite positioning system, referred to as GPS, can provide users with accurate location, speed, time and other information on a global scale, and has been widely used. The GPS system is the earliest and most mature navigation and positioning system. Due to the superiority of GPS, it has attracted widespread attention. It has a wide range of applications, including providing navigation services for users anywhere on the earth's surface, near the earth's surface, and in outer space, but there are still limitations: such as In complex environments such as ind...

AI Technical Summary

Problems solved by technology

Due to the superiority of GPS, it has attracted widespread attention. It has a wide range of applications, including providing navigation services for users anywhere on the earth's surface, near the earth's surface, and in outer space, but there are still limitations: such as In complex environments such as indoors, forests, and cities, where the signal will be attenuated to a very weak level, GPS will not work well

These two methods have certain defects: for coherent integration, due to the limitation of data bit jumps, the length of coherent integration generally cannot exceed one data bit, that is, 20ms, otherwise it may be caused by data bits. The jump of the coherent integration makes the coherent integral value smaller or even cancels out, so the time of the coherent integration cannot be increased without limit; although the non-coherent integration method can use the square operation to overcome the influence of the data bit jump, it is also It inevitably causes square loss, which weakens the gain of signal-to-noise ratio, so it cannot perform unlimited non-coherent integration

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