GPS weak signal capturing method based on difference circulation coherent integration

Abstract

The invention provides a GPS weak signal capturing method based on difference circulation coherent integration. The method includes the steps that step1, a section of 20 ms+12 ms intermediate frequency is selected for receiving a signal, carrier wave stripping treatment and frequency mixing treatment are performed, and a Doppler frequency shift range, a search frequency stepping and a detection threshold value are set; step2, data partitioning treatment is performed on the signal after carrier wave stripping at the length of 4 ms, data blocks are respectively superposed, and then FFT treatment is performed on the data blocks; step3, FFT is performed on a C / A code generated locally, a conjugate is extracted, then the conjugate and all final results obtained in the step2 are multiplied, and IFFT treatment is performed; step4, the adjacent four data blocks multiply in a complex number conjugate mode after the treatment in the step3, then related grouping summation is performed, and obtained results are judged to determine whether capturing is successful or not. The GPS weak signal capturing method is used for capturing the weak signal through a GPS single-frequency civil software receiver.

Description

technical field [0001] The present invention relates to a method for capturing and processing a receiver in a Global Navigation Satellite System (GNSS—Global Navigation Satellite System), in particular to a GPS—Global Positioning System (GPS—Global Positioning System) single-frequency civilian software receiver for weak signal capture method. Background technique [0002] 2 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 indoors, forests, and cities, where t...

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

However, 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. There is an offset phenomenon, so it is not possible to increase the time of coherent integration without limit

Although the incoherent integration method can use the square operation to overcome the influence of data bit jumps, it will inevitably cause square loss and weaken the gain of the signal-to-noise ratio, so it cannot perform unlimited non-coherent integration.

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