A digital phase-locked loop atomic clock control method equivalent to a two-state variable kalman filter

Abstract

A digital phase-locked loop atomic clock control method equivalent to a two-state variable Kalman filter uses a cesium clock to control a hydrogen clock through a DPLL equivalent to a two-state variable Kalman filter. Firstly, the closed-loop system transfer function of the DPLL is derived, and it is proved that the DPLL is a second-order type 2 DPLL. Then the Kalman gain, which is approximately determined by the ratio of process noise variance to observation noise variance, is derived. Therefore, it can be seen from the closed-loop transfer function of the DPLL that the ratio, loop gain, and sampling interval determine the performance of the DPLL. Further, the present invention provides a simple and effective method for selecting parameters. Through equivalent transformation, an analog phase-locked loop (APLL) equivalent to the DPLL is obtained. In the frequency domain, by adjusting the parameters, the intersection frequency of the system transfer function and the error transfer function of the equivalent APLL is equal to the intersection frequency of the SSB phase noise curves of the hydrogen clock and the cesium clock, and finally the optimal parameters are obtained. It effectively uses the cesium clock to control the hydrogen clock, and the control performance is very good.

Description

technical field [0001] The invention relates to the fields of time frequency and signal processing, and specifically designs a digital phase-locked loop atomic clock control method equivalent to a two-state variable Kalman filter. Background technique [0002] Atomic clock-driving technology plays an important role in timekeeping laboratories and satellite navigation systems. There are two main purposes of driving the atomic clock: one is to synchronize the time of the controlled atomic clock with the reference atomic clock, and minimize the time deviation between them; the other is to improve the long-term stability of the controlled atomic clock. [0003] Typical atomic clock driving methods include two categories: open-loop driving methods and closed-loop driving methods. The core of the open-loop driving method is to design a reasonable prediction algorithm. Closed-loop control methods mainly include: linear quadratic (LGQ) control method, switch (Bang-Bang) control me...

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Problems solved by technology

In addition, for the DPLL method, if the parameters are not selected properly, not only the driving performance cannot be guaranteed, but also the control system will be unstable.

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