QUESTION:
A. What causes Frequency and MTIE Errors? How can I know if these type of errors are occuring, and how can I correct for them?
ANSWER:
Network frequency and MTIE limits are exceeded for a variety of reasons. If, for example, a network equipment element loses connection to primary reference timing and relies on an internal free-running local oscillator for timing instead, it can drift off frequency which will lead to both frequency and MTIE network limits being exceeded.
One way to determine whether these kinds of timing errors are occurring is to measure the signal directly with a synchronization test-set that is itself locked to a primary reference source. This kind of instrumentation generally makes direct measurements of phase, which can be used for making frequency and MTIE calculations. The MTIE (maximum time interval error) calculation is made by sliding specific time windows through the phase data while looking for maximum phase excursions (see attached file).
Deploying network synchronization equipment such as GPS timing receivers and SSUs (sychronization supply units) can be used to supply primary reference source quality timing to network equipment, thus avoiding the issues connected with excessive MTIE and large frequency inaccuracies.
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