Measurement Methods and Algorithms for Comparison of Local and Remote Clocks

摘要

We will discuss several methods for characterizing the performance of clocks with special emphasis on using calibration information that is acquired via an unreliable or noisy channel. We will discuss time-domain variance estimators and frequency-domain techniques such as cross-spectral analysis. Each of these methods has advantages and limitations that we will illustrate using data obtained via GPS, ACTS and other methods. No one technique will be optimum for all of these analyses, and some of these problems cannot be completely characterized by any of the techniques we will discuss. We will also discuss the inverse problem of communicating frequency and time corrections to a real-time steered clock. Methods have been developed to mitigate the disastrous problems of data corruption and loss of computer control.