GPS (Global Positioning System) signal acquisition method based on FPGA (Field Programmable Gate Array) and GPS signal acquisition system
A technology of GPS signal and GPS receiver, which is applied in FPGA-based GPS signal acquisition method and its system field, can solve the problems of acquisition phase error, long acquisition time, complex system circuit, etc., achieve data points reduction, resource saving, The effect of reducing the amount of computation
Inactive Publication Date: 2013-01-30
SOUTHEAST UNIV
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Problems solved by technology
It solves the technical problems of the existing capture method and system circuit, such as complex circuit, long capture time, unfavorable FPGA platform implementation, and capture phase error.
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[0043] 1) Platform: The FPGA core chip uses the cyclone III series EP3C40Q240C8.
[0044] 2) Development environment: ModelSim and Quartus, the software language used is Verilog, the development process is to use the ModelSim tool to realize the GPS signal fast and precise capture system function simulation, use Quartus to synthesize the realized software, and then use the ModelSim tool to perform timing simulation, After the simulation is completed, the software is downloaded to the FPGA hardware platform, thus completing the GPS signal fast and precise capture system.
[0045] 3) 5.714MHZ clock generation module: the clock on the hardware platform is 40MHZ, and the 5.714MHZ clock is generated by dividing by 7.
[0046] 4) GPS signal storage module: The GPS signal has been quantized into 2 bits, the quantized values are ±1 and ±3, using 5714 * 2 dual-port RAM to store, and use a Mealy-type state machine to realize the read and write control of RAM.
[0047] 5) Numerical c...
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The invention discloses a GPS (Global Positioning System) signal acquisition method based on an FPGA (Field Programmable Gate Array), which comprises the following steps of: firstly, carrying out down sampling on a medium-frequency acquisition signal by adopting an average sampling method; taking data obtained by averaging the energy of a point during each sampling period as sample data subjected to down sampling, wherein the averagely-sampled points meet 2FFT (Fast Fourier Transformation) operation; finishing initial acquisition of the GPS signal to obtain an initial phase range of a pseudocode and initial carrier frequency; and carrying out further fine acquisition by using a time domain correlation algorithm to obtain accurate initial phase of the pseudocode and carrier frequency. An FPGA hardware platform is set up in the acquisition system and is combined with a radio-frequency front-end chip of a GSP receiver; and the acquisition system comprises a clock generation module, a main control module realized by a state machine, a GPS signal storage module, a carrier oscillator module, a carrier stripping module, a pseudocode reading module, an average sampling module, an FFT(Fast Fourier Transformation) / IFFT (Inverse Fast Fourier Transform) module, a threshold decision and initial phase calculation module and a fine acquisition module realized by a correlator.
Description
technical field [0001] The invention belongs to the technical field of GPS satellite positioning and reception, in particular to an FPGA-based GPS signal acquisition method and a system thereof realized by using an FPGA hardware platform. Background technique [0002] The GPS software receiver performs baseband signal processing through software. Compared with the traditional ASIC (special hardware chip) hardware receiver, the software receiver has the characteristics of openness, flexibility and scalability. The needs of different users can be met by adjusting and upgrading the software parameters, which greatly reduces the cost required for system upgrading. [0003] Field Programmable Gate Array (FPGA) has the advantages of flexibility and fast processing. Its interior is composed of regular logic arrays, and special chips can be developed to make the product very small and easy to carry. FPGA has rich logic resources inside, its configuration is flexible, and it can pro...
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IPC IPC(8): H04L27/00G01S19/30G01S19/29
Inventor 潘树国王庆赵丽毛志鹏
Owner SOUTHEAST UNIV