基于GPS驯服压控晶体振荡器的设计与实现
发布时间：2018-10-22 08:05
【摘要】：频率源的频率稳定度是衡量通信系统质量好坏的一个重要指标,以频率稳定度的测量时间间隔为区分可以把频率稳定度分为长期频率稳定度和短期频率稳定度,实际的高稳频率源系统通常需要同时具有优秀的长期稳定度和短期稳定度。GPS是卫星导航定位授时系统,能够给用户提供导航、定位,授时等服务。晶体振荡器的特点是具有好的短期稳定度优点。而GPS授时的频率信号具有长期稳定度好的特点。结合两者的优点,本文设计了一个基于GPS来校准压控晶振的驯服技术。压控晶振采用了基于SC切的晶体谐振器的设计,介绍了 SC切压控晶振的构成,详细讲述了各部分的电路设计和工作原理,信号输出为10MHz。本文设计的压控晶振有体积小,成本低,功耗小诸多优点。在驯服技术中,采用了一种基于锁相环技术的时间间隔测量法。利用PLL产生均匀延迟的多路参考频率信号,在由时间间隔形成的闸门下对其计数,以计数值的平均数作为参考频率计数值,降低了测量误差。介绍了锁相环原理,各组成模块的功能特性及其线性化模型,并对锁相环路的性能做了理论分析,为具体改进电路结构以提高环路性能提供了理论依据。然后,论文介绍了本设计各模块的硬件设计。通过仿真实现GPS的1PPS与本地压控晶振分频产生的秒脉冲时间间隔的测量。软件部分的设计用MSP430单片机和FPGA做为控制单元的核心。实现的时间间隔测量模块具有分辨率精度高,稳定性好的特点。基于上述技术,本文对基于GPS驯服压控晶振的系统的设计和实现方式做了具体介绍。实际结果表明,利用GPS对压控晶振VCXO进行驯服的让长期稳定度有一定程度的改善。最后对该频率源系统的实验结果进行分析,表明了该设计方案通过锁相环合成GPS频率信号和本地VCXO频率信号以实现长期稳定度和短期稳定度皆优的频率源系统的可行性。
[Abstract]:The frequency stability of the frequency source is an important index to measure the quality of the communication system. The frequency stability can be divided into long term frequency stability and short term frequency stability according to the measurement time interval of frequency stability. Practical high-stability frequency source systems usually need both excellent long-term stability and short-term stability. GPS is a satellite navigation and positioning system which can provide users with navigation, positioning, timing and other services. Crystal oscillators are characterized by good short-term stability. The frequency signal of GPS timing has good long-term stability. Combining the advantages of the two, a taming technique based on GPS is designed to calibrate the voltage controlled crystal oscillator. The design of the crystal resonator based on SC is used in the voltage-controlled crystal oscillator. The structure of the SC voltage-controlled oscillator is introduced. The circuit design and working principle of each part are described in detail. The signal output is 10 MHz. The voltage controlled crystal oscillator designed in this paper has many advantages, such as small volume, low cost and low power consumption. In the taming technique, a time interval measurement method based on phase locked loop (PLL) is adopted. The multichannel reference frequency signal with uniform delay is generated by PLL and counted under the gate formed by the time interval. The average value of the count value is used as the reference frequency value to reduce the measurement error. This paper introduces the principle of PLL, the functional characteristics of each module and its linearization model, and makes a theoretical analysis of the performance of PLL, which provides a theoretical basis for improving the circuit structure and improving the performance of PLL. Then, the paper introduces the hardware design of each module. The measurement of the time interval between the 1PPS of GPS and the time interval of the second pulse produced by local voltage-controlled crystal oscillator is realized by simulation. Software part of the design using MSP430 MCU and FPGA as the core of the control unit. The time interval measurement module has the characteristics of high resolution precision and good stability. Based on the above technology, the design and implementation of the system based on GPS taming voltage controlled crystal oscillator are introduced in detail. The practical results show that the long term stability of VSCO VCXO is improved to some extent by using GPS to tame the VSCO. Finally, the experimental results of the frequency source system are analyzed, and it is shown that the design scheme is feasible to synthesize GPS frequency signal and local VCXO frequency signal by phase-locked loop to realize the frequency source system with both long-term and short-term stability.
【学位授予单位】：兰州大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TN752;P228.4
本文编号：2286588
[Abstract]:The frequency stability of the frequency source is an important index to measure the quality of the communication system. The frequency stability can be divided into long term frequency stability and short term frequency stability according to the measurement time interval of frequency stability. Practical high-stability frequency source systems usually need both excellent long-term stability and short-term stability. GPS is a satellite navigation and positioning system which can provide users with navigation, positioning, timing and other services. Crystal oscillators are characterized by good short-term stability. The frequency signal of GPS timing has good long-term stability. Combining the advantages of the two, a taming technique based on GPS is designed to calibrate the voltage controlled crystal oscillator. The design of the crystal resonator based on SC is used in the voltage-controlled crystal oscillator. The structure of the SC voltage-controlled oscillator is introduced. The circuit design and working principle of each part are described in detail. The signal output is 10 MHz. The voltage controlled crystal oscillator designed in this paper has many advantages, such as small volume, low cost and low power consumption. In the taming technique, a time interval measurement method based on phase locked loop (PLL) is adopted. The multichannel reference frequency signal with uniform delay is generated by PLL and counted under the gate formed by the time interval. The average value of the count value is used as the reference frequency value to reduce the measurement error. This paper introduces the principle of PLL, the functional characteristics of each module and its linearization model, and makes a theoretical analysis of the performance of PLL, which provides a theoretical basis for improving the circuit structure and improving the performance of PLL. Then, the paper introduces the hardware design of each module. The measurement of the time interval between the 1PPS of GPS and the time interval of the second pulse produced by local voltage-controlled crystal oscillator is realized by simulation. Software part of the design using MSP430 MCU and FPGA as the core of the control unit. The time interval measurement module has the characteristics of high resolution precision and good stability. Based on the above technology, the design and implementation of the system based on GPS taming voltage controlled crystal oscillator are introduced in detail. The practical results show that the long term stability of VSCO VCXO is improved to some extent by using GPS to tame the VSCO. Finally, the experimental results of the frequency source system are analyzed, and it is shown that the design scheme is feasible to synthesize GPS frequency signal and local VCXO frequency signal by phase-locked loop to realize the frequency source system with both long-term and short-term stability.
【学位授予单位】：兰州大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TN752;P228.4
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