Introduction to Timing and Synchronisation

Timing dependent applications rely on their clocks being correct within the set tolerances required by that technology.In order to achieve this, timing is transferred between clocks using various methods that enable time or frequency, phase or time of the required quality to be available to the application.The activity of transferring time between clocks is known as synchronisation.

Timing and synchronisation quality can be described by two factors:accuracy and stability.Accuracy is the measure of how closely the clock compares to a reference or target value; this can be a global standard for time such as UTC or a desired frequency such as 10MHz; stability is the measure of the variance of the clock when observed over a period of time.

In order to quantify the quality of timing and synchronisation, many different timing metrics exist.These are specifically designed for the timing technologies they are measuring and the characteristics of the signal that are of interest.Measurements must be made against another clock of known and dependable quality during relevant network or environmental conditions and over a period of time long enough to fully characterise the measured clock.