GPS positioning initialization method of vehicle-mounted navigation device

Abstract

The invention provides a GPS positioning initialization method of a vehicle-mounted navigation device. The GPS positioning initialization method comprises the steps of: firstly, recording a latest ephemeris updating moment T0, a GPS terminal equipment turning-off moment T1, a restarting moment T2 and a running speed V of a vehicle, and then measuring a distance Smax that the vehicle runs during a period from an updating moment to a failure moment of an ephemeris; calculating a distance S2 that the vehicle runs during a period from a turning-off moment to a restarting moment of GPS terminal equipment and a distance S1 that the vehicle runs during a period from a latest ephemeris updating moment to a turning-off moment; and selecting different positioning methods according to a magnitude relation between S1+S2 and the Smax as well as a magnitude relation between T2-T0 and a ephemeris updating cycle T. The GPS positioning initialization method judges whether the ephemeris is valid based on timeliness and territoriality, adopts different positioning methods according to different judgment results, and avoids a large amount of time consumption caused by blindly using the single one of the positioning methods.

Description

technical field [0001] The invention relates to the field of vehicle navigation, in particular to a GPS positioning initialization method for vehicle navigation. Background technique [0002] The Global Positioning System (GPS) needs to go through processes such as capture, frequency traction, tracking, demodulation, and calculation before it can determine the location of the receiver. This process often takes a long time. Once the GPS terminal is positioned Successfully, in the memory of the GPS receiving chip, the following two data are generally kept / updated: 1. The latitude and longitude of the last positioning, 2. The ephemeris of the last positioning position. Because the ephemeris is time-sensitive and regional, these two data are very critical. When the GPS is turned off or loses signal, when it starts up again to receive satellite signals, if it is within the validity period of the ephemeris, it does not need to calculate the satellite orbit, just simply adjust the...

AI Technical Summary

Problems solved by technology

After the GPS is turned off, if the vehicle has driven a certain distance, the area of ​​the GPS ephemeris saved in the system may be invalid. At this time, when the system is turned on for positioning, the latitude, longitude and ephemeris information of the last position recorded in the system not only cannot be quickly located, but will increase. positioning time

For the navigation system, how to quickly select the positioning method is the key to achieving fast positioning. The patent document with the application number "200810056632.4" and the invention title "A Management Method for Navigation Messages of Global Positioning System Receivers" records a method for realizing the last record The ephemeris of a positioning position, and the selection of positioning algorithms based on the judgment of the validity of the ephemeris based on time, but the regional validity of the ephemeris is not considered

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