Avoiding Aliasing in Allan Variance: an Application to Fiber Link Data Analysis

TL;DR

This paper addresses the challenge of aliasing in Allan variance analysis of optical fiber links, proposing adapted signal analysis tools to improve stability estimation without additional estimators, demonstrated on a 1284 km fiber link.

Contribution

It introduces a method to avoid aliasing in Allan variance calculations for optical fiber links, enhancing accuracy using standard signal analysis tools.

Findings

Effective aliasing mitigation in Allan variance analysis.

Validated approach on a 1284 km optical fiber link.

Improved stability estimation accuracy.

Abstract

Optical fiber links are known as the most performing tools to transfer ultrastable frequency reference signals. However, these signals are affected by phase noise up to bandwidths of several kilohertz and a careful data processing strategy is required to properly estimate the uncertainty. This aspect is often overlooked and a number of approaches have been proposed to implicitly deal with it. Here, we face this issue in terms of aliasing and show how typical tools of signal analysis can be adapted to the evaluation of optical fiber links performance. In this way, it is possible to use the Allan variance as estimator of stability and there is no need to introduce other estimators. The general rules we derive can be extended to all optical links. As an example, we apply this method to the experimental data we obtained on a 1284 km coherent optical link for frequency dissemination, which we realized in Italy.