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Method and device for GPS navigation message data bit synchronization under weak signals

A technology of GPS navigation and navigation message, which is applied in the field of GPS positioning and navigation, can solve problems such as the difficulty of accurately determining navigation message data, and achieve the effect of small demand, accurate calculation, and fast bit synchronization operation

Inactive Publication Date: 2009-12-30
SHANGHAI INFOTM MICROELECTRONICS
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Problems solved by technology

However, in the case of weak GPS satellite signals, it is very difficult to accurately determine the navigation message data by the signal tracking function of the GPS receiver, which limits the overall sensitivity of the conventional GPS receiver to the demodulation of the navigation message data

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  • Method and device for GPS navigation message data bit synchronization under weak signals
  • Method and device for GPS navigation message data bit synchronization under weak signals
  • Method and device for GPS navigation message data bit synchronization under weak signals

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Embodiment Construction

[0032] The specific implementation of the method for synchronizing GPS navigation message data bits under weak signals of the present invention will be described in detail below with reference to the accompanying drawings.

[0033] See Figure 5 , Figure 5 Navigation message data structure diagram modulated for GPS satellite signal, such as Figure 5 As shown, the smallest unit of the navigation message data of the GPS satellite is bit, and its length is 20 milliseconds, occupying a total of 20 C / A chips. That is, every 20 standard 1 millisecond represents one bit. Therefore, to obtain satellite navigation message data, the first thing you need to do is to find and lock the 1-millisecond boundary of a bit of data every 20 milliseconds. That is, continuous 1-millisecond data is divided into 20-millisecond data by grid. This operation is called Bit synchronization. Figure 5 Where X is 1 frame is 5 subframes; Y is 1 subframe is 10 words; Z is 1 word is 10 bits (bit); W is the 4th and 5...

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Abstract

The invention discloses a method and a device for GPS navigation message data bit synchronization under weak signals. The method comprises the following steps: when a GPS receiver enters a GPS satellite signal capturing state, acquiring and obtaining GPS satellite signal data to be captured; calculating the maximum likelihood rate of a bit boundary in single-navigation message data bits; calculating the maximum likelihood rate of a navigation message data bit boundary with a set length; and according to the calculation results, judging the boundary and data values of accurate navigation message data bits, and judging whether the signal is output to a GPS signal tracking module to assist the tracking function till having the auxiliary tracking function, and carrying out bit synchronization operation. Under the condition that the GPS satellite signals are weak, the method and the device can quickly and accurately acquire the exact position of phase turnover of the GPS navigation message data so that the GPS receiver successfully enters a tracking state to realize the positioning function.

Description

Technical field [0001] The invention relates to the field of GPS (Global Positioning System) positioning and navigation, and more specifically, to a method and a device used for a GPS satellite positioning and navigation receiver to realize GPS navigation message data bit synchronization when the GPS satellite signal is weak . Background technique [0002] GPS positioning technology uses high-altitude GPS satellites to transmit L-band carrier frequency radio ranging signals to the ground, which are continuously received by user receivers on the ground in real time, thereby calculating the location of the receiver antenna. The space part of the GPS system is composed of GPS satellites, called a satellite constellation. The distribution of satellite constellations should ensure that at least four satellites can be observed at any time at any point on the earth. [0003] When GPS satellites rise in the user’s horizon, the user receiver on the ground can capture the signals of the sa...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01S5/02
Inventor 刘春晖金荣伟李兴仁林锦麟张正荣陈谦
Owner SHANGHAI INFOTM MICROELECTRONICS
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