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Time-frequency crystal tame technology is a time synchronization and timingacquisition method, currently widely used at home and abroad, the main application ofdigital phase-locked loop control technology, timing crystal obey the satellite, resulting inhigh precision and high stability clock source. In terms of hardware, in the past, thegeneral use of the SCM, insufficient range of applications, this system, using the FPGAchip, easier programming and extensions, simplifying the hardware design, PCB boardincludes only FPGA chip, oven controlled crystal oscillator, A/D converter, a memory, aninterface, digital phase locked loop completed most of the functions within the FPGA. Interms of software, using SOPC system based on FPGA, which is the control center of theentire circuit, innovatively, using a soft-core processor NiosII and configure user-definedfunction module unit, complete the crossover frequency, digital phase, delay and otherhardware features, wherein the delay time is the key to ensure accuracy, the tap each level,i.e., TDC accuracy is426ps, thereby ensuring the accuracy of the system level ns.Phase-locked loop filter design algorithm is a top priority, taking into account the morecomplex the system noise, proposed a Algorithmic Theory, combined with Kalmanfiltering and PI control advantages of both, Matlab software simulation results show theneed for process of handling noise about70ns, performance test of the hardware circuit,the oscilloscope stable, indicating seconds precision is about2ns. Of China’s Beidousystem is gradually improving, crystal tame technology will be applied to more areas, withgood economic and social significance.
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