Signal detection and judgment method and device in capture of weak satellite navigation signal

Abstract

The invention discloses a signal detection and judgment method and device in the capture of a weak satellite navigation signal. In a weak-signal environment, a high-sensitivity satellite navigation receiver needs to accumulate correlated results of a pseudo code for a long time so as to meet the sensitivity gain requirement of capture. The invention aims to reduce the SNR (Signal-to-Noise Rate) loss brought from a detection and judgment process of the correlated results by using a signal-based PAPR (Peak-To-Average Power Ratio) judging method and provides a self-adaptive treatment method for judging a threshold. Meanwhile, in the invention, the influence of a near-far effect is considered, and a judging module for removing cross correlation after primarily judging signal existence is provided so as to weaken the influence of the cross correlation interference of C / A (Coarse / Acquisition) codes. A control module carries out two-dimensional search on a capturer, and a method for detecting a maximum value falling trend is used for judging Doppler frequency shift existing in the current signal so as to shorten the search time of a frequency dimension and increase the capture efficiency. The invention is suitable for systems such as a GPS (Global Positioning System), BD-2 (BeiDou-2), and the like and can achieve the cold-boot capture sensitivity up to -145dbm.

Description

technical field [0001] The invention relates to a signal detection and judgment method and a device thereof in weak satellite navigation signal acquisition. Background technique [0002] GNSS (Global Navigation Satellite System), as a satellite-based navigation system, uses information such as the distance or direction angle from the user to the satellite whose position is known for positioning and navigation. In recent years, with the major GNSS systems With continuous improvement, satellite navigation technology has not only penetrated into military fields such as military, surveying and mapping, communication, and remote sensing, but also has been widely used in civilian fields such as automobile positioning systems and personal handheld communication terminals. Because of its important strategic position and unlimited market potential, satellite positioning technology has become the focus and focus of research and development in various countries. [0003] The satel...

AI Technical Summary

Problems solved by technology

Whether it is non-coherent accumulation or differential coherent accumulation, the sensitivity gain brought by integration is limited, and the decision process based on the amplitude of the accumulation result will introduce sensitivity loss

For the capture scheme itself, the weak signal environment in which it is located cannot be set, so the noise floor in signal capture is difficult to count its distribution

In addition, the use of different RF front-ends in the receiver will also affect the size of the noise floor in the signal capture results

Therefore, it can be clearly seen that the fixed threshold decision based on Gaussian distribution is not the best choice

Images