Method of measuring timing holdover performance in an R-PHY system
Systems and methods for measuring the amount of drift of a clock in a remote device relative to a clock in a core, both in a distributed access architecture, by measuring the change in fullness of a dejitter buffer in the remote device that holds data provided from the core.
1. A remote device in a distributed access architecture of a communications network, the remote device operatively connected to a core providing data to the remote device, the remote device including a dejitter buffer and a processor configured to measure sequential values, each value representing an instantaneous fullness state of the dejitter buffer, and use the values to determine a magnitude of phase drift of a first clock of the remote device relative to a second clock of the core;
the remote device including a low pass filter that filters the sequential values; and
where the output of the low pass filter is used to determine a sequence of fractional frequency offset values.
2. The remote device of claim 1 where the processor accumulates the sequence of fractional frequency offset values to provide an accumulated value and compares the accumulated value to a threshold.
3. The remote device of claim 2 where the remote device provides an alert based on the comparison.
4. A method implemented by a processor of a network device in a distributed access architecture, the method comprising:
measuring sequential values representing a fullness state of a dejitter buffer of the network device, the network device having a first clock;
using the sequential values to determine a magnitude of phase drift of the first clock relative to a second clock associated with a second device providing data to the dejitter buffer;
applying a low pass filter to the sequential values;
where the output of the low pass filter is used to determine a sequence of fractional frequency offset values.
5. The method of claim 4 further comprising accumulating the sequence of fractional frequency offset values to provide an accumulated value.
6. The method of claim 5 further comprising comparing the accumulated value to a threshold.
7. The method of claim 6 further comprising providing an alert based on the comparison.