Method and apparatus for realizing high precision three stage clock

Abstract

The invention discloses a method and device for realizing a high-precision three-level clock. The device includes a GPS receiver, a digital phase detector, a CPU, a constant temperature voltage-controlled crystal oscillator and a DDS, and the constant temperature voltage-controlled crystal oscillator outputs a stable clock signal. to the DDS; the DDS processes the clock signal input by the constant temperature voltage-controlled crystal oscillator according to the command of the CPU, outputs the processed clock signal, and feeds the output clock signal back to the digital phase detector; the digital phase detector responds to the feedback clock signal Perform phase detection with the standard signal input by the GPS receiver and input the phase detection result to the CPU; the CPU controls the DDS according to the phase detection result so that it outputs a signal close to the required frequency. The invention can ensure that the frequency of the clock signal output to the system connected with it is stable in the short term and long term, thereby ensuring the accuracy and quality of data transmission of other systems connected with it.

Description

Technical field: [0001] The invention relates to a method and a device for realizing a high-precision three-level clock. Background technique: [0002] At present, GPS (Global Satellite Positioning System) and constant temperature voltage-controlled crystal oscillator are generally used to realize high-precision clock system, such as figure 1 As shown, the GPS receiver is connected to the digital phase detector, the digital phase detector is connected to the CPU, the CPU (central processing unit) is connected to the constant-temperature voltage-controlled crystal oscillator through the D / A converter, and the constant-temperature voltage-controlled crystal oscillator is connected to the digital phase detector. The standard second signal output by the GPS receiver and the signal (about 10MHZ) output by the constant temperature voltage-controlled crystal oscillator are phase-identified through the digital phase detector, and the frequency of the signal and the standard signal (...

AI Technical Summary

Problems solved by technology

Using the above method, generally speaking, GPS can guarantee long-term frequency stability and accuracy, and the output frequency of the constant temperature voltage-controlled crystal oscillator can reach the required accuracy, that is, it can guarantee the clock output accuracy in the digital synchronization network, but in the short term, The output accuracy cannot be guaranteed, because the above method needs to output an analog voltage through the D / A converter to control the oscillation frequency of the constant temperature voltage-controlled crystal oscillator, and the analog signal will be subject to various external interferences at all times, resulting in constant temperature The output frequency of the voltage-controlled crystal oscillator is unstable, that is to say, due to the instability of the analog voltage, the output frequency of the constant-temperature voltage-controlled crystal oscillator is always fluctuating, so that the system using this device, such as a digital synchronization network, will have errors The emergence of codes, etc., affect the quality of data transmission

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