A Different Approach to Control of a Rubidium–Based GNS Disciplined Frequency Standard

by Precise Time and Frequency, Inc.

Many applications utilizing precision frequency references use an OCXO as the local oscillator to provide improved accuracy and stability, however it is not uncommon to require the additional stability and holdover performance provided by incorporating a rubidium atomic clock as the local oscillator in a GNS disciplined standard.

Many of these systems also require a precision timing signal (e.g. one pulse per second or 1PPS) to synchronize in the time domain to UTC (Universal Time Coordinated).

Disciplining (or “steering”) either an OCXO or a rubidium oscillator to UTC while at the same time preserving the inherent excellent stability performance of the rubidium is not a trivial task. Recent development work on a new product at PTF yielded the opportunity to consider a different strategy for control implementation.

This paper describes both the traditional OCXO control and an alternative method to the more commonly used PID type control loop used for the rubidium.

This article contains formulas. To make it easier to read please click here for the pdf version of the article.

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