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目前高精度时钟均采用高精度恒温晶振实现,文中提出使用普通温补晶振实现高精度时钟的新方案。该方案利用外部时钟源的秒脉冲宽度测量晶振频率,减小频率测量误差;通过测量频率及温度计算晶振的温度系数,利用该系数计算秒脉冲宽度,并将该宽度和外部时钟源的秒脉冲宽度相比较,将比较结果计入温度系数计算中,进一步降低了误差,提高了温度系数的精度。这些措施为提高时钟的守时精度奠定了基础。同时,文中详细分析了方案的误差源,并给出了工程应用实例。
Currently, high-precision clocks are implemented with high-precision, constant-temperature crystals, and a new scheme of using high-precision clocks by using ordinary temperature-compensated crystals is proposed in the paper. The program uses the second clock pulse width of the external clock source to measure the crystal oscillator frequency and reduce the frequency measurement error. The temperature coefficient of the crystal oscillator is calculated by measuring the frequency and temperature. The second pulse width is calculated by using this coefficient, Compared with the width, the results will be included in the calculation of temperature coefficient, to further reduce the error and improve the accuracy of the temperature coefficient. These measures laid the foundation for improving the punctual accuracy of the clock. At the same time, the paper analyzes the error sources of the scheme in detail and gives examples of engineering application.