Frame synchronization method of GPS receiver

A GPS receiver and frame synchronization technology, applied in satellite radio beacon positioning systems, measuring devices, instruments, etc., can solve problems such as interruption of positioning services, achieve the effects of overcoming time-consuming, improving timing accuracy, and increasing synchronization speed

Active Publication Date: 2011-03-02
BEIJING AEROSPACE AUTOMATIC CONTROL RES INST
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AI Technical Summary

Problems solved by technology

Because each channel of the receiver needs to perform frame synchronization independently, multi-channel receivers need longer time to complete the frame synchronization of all channels, which will lead to serious interruption of positioning services in applications where satellite signals are easily blocked

Method used

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  • Frame synchronization method of GPS receiver
  • Frame synchronization method of GPS receiver
  • Frame synchronization method of GPS receiver

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Embodiment Construction

[0029] Such as figure 1 As shown, it is a flow chart of the fast frame synchronization method for the GPS receiver of the present invention, and each step will be described in detail below.

[0030] (1) After the GPS receiver is turned on and positioned for the first time, the local clock is periodically adjusted so that the time and change period of the local clock and the GPS clock are consistent.

[0031] Usually, the time difference compensation method is used to adjust the GPS local clock, that is, to periodically compensate the local time based on the time difference between the GPS time and the local time. This method cannot compensate the local clock drift. In the method of the present invention, a direct digital frequency synthesizer (DDS) is adopted to adjust the local clock, and the time difference between GPS time and local time is periodically converted into a local time DDS frequency control word to directly adjust the timing frequency of the local time. The clo...

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Abstract

A frame synchronization method of a GPS receiver comprises the following steps: (1) after the GPS receiver is turned on and is fixed firstly, the local clock is adjusted periodically to ensure that the times and variation periods of the local clock and the GPS clock are consistent, the current position of the GPS receiver is recorded; (2) after the channel of the GPS receiver is unlocked and recaptured, the local time and ephemeris are read, the preliminary position of the satellite is calculated according to the ephemeris and the approximate launch time of satellite signals; (3) the uncorrected approximate distance of the GPS receiver and the satellite is calculated according to the recorded initial position of the GPS receiver and the preliminary position of the satellite so as to obtain pseudorange; (4) the local time is corrected according to the time used for executing the step (2) and the step (3) to obtain the satellite launch time of the current teletext; and (5) the frame count, bit count and millisecond count of the current teletext are calculated according to the result of the step (4), and frame synchronization is performed to extract the teletext.

Description

technical field [0001] The invention relates to a data frame synchronization method. Background technique [0002] After the GPS receiver channel captures the satellite signal, the bit synchronization and frame synchronization of the satellite signal must be completed before the navigation message decoding and positioning solution can be performed. Frame synchronization takes a lot of time in the steps from capturing satellite signals to providing navigation services. Reducing the frame synchronization time is critical to improving receiver start-up speed. [0003] The existing frame synchronization method mainly searches the 8-bit synchronization code of the telemetry word to determine the edge of the subframe, and confirms the correctness of the search result by means of parity check and handover word feature check. Because the GPS subframe period is 6 seconds, and the synchronization code only exists in the first 8 bits of the telemetry word, it takes a maximum of one s...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04B7/26G01S19/13
Inventor 宋鹏飞陈怡田琨葛飞韩琦
Owner BEIJING AEROSPACE AUTOMATIC CONTROL RES INST
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