Low-cost timing and synchronization method and device for global positioning system receiver

Abstract

The present invention is a low-cost timing and synchronization method and equipment for a global positioning system receiver, which relates to the field of time granting and synchronization, and in particular to a baseband processing chip based on a global positioning system, such as the global positioning system (GPS) of the United States. Low-cost timing and synchronization domains implemented at the level. The invention improves the timing and synchronization method based on the global positioning system, and realizes it based on the global positioning system baseband processing chip device. The invention performs soft calibration on the crystal oscillator through the coordinated universal time calculated by the global positioning system, realizes time service to external equipment through the combination of time code and synchronous pulse signal, and uses low-cost crystal oscillator to realize high-precision time service. At the same time, the invention does not need to calibrate the crystal oscillator in the form of hardware, greatly simplifies the system design, reduces the cost, and has the advantages of small hardware overhead, strong scalability, and high reliability.

Description

technical field [0001] The invention relates to the field of time grant and synchronization, in particular to a global positioning system, and belongs to the field of low-cost time service and synchronization realized at the baseband processing chip level. Background technique [0002] Global satellite positioning and navigation systems, such as the United States' Global Positioning System (GPS), consist of a constellation of satellites (also known as Navstar satellites) that transmit GPS signals that can be used by a receiver to determine the receiver's Location. Satellite orbits are arranged in multiple planes so that the signal can be received from at least four satellites at any location on Earth. More typically, the signal is received from more than six satellites in most places on Earth. The GPS signal transmitted by each GPS satellite is a direct sequence spread frequency signal. The commercially used signal is related to the Standard Positioning Service (SPS) and ...

AI Technical Summary

Problems solved by technology

Existing timing schemes often convert GPS time into analog quantities to directly compensate the crystal oscillator, but this type of scheme has a complex structure, and the introduction of analog circuits introduces additional design difficulties and problems, greatly increasing the cost, and the system stability is not high

And it needs to customize the crystal oscillator and its compensation circuit, and only TCXO can be used instead of OCXO

At the same time, due to real-time compensation, the frequency between two calibrations is unstable

Other solutions use digital frequency synthesis DDS to achieve frequency output, solving the problem of frequency instability between two calibrations

However, its frequency stability is still based on the crystal oscillator of DDS. At the same time, the structure of this scheme is more complicated. A complex coding control circuit is required between the GPS baseband processing chip and DDS, and the cost is high.

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