Title: Timing characteristics of packet-based equipment clocks (frequency)

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Summary

Packet-Based Equipment Slave Clock for Frequency (PEC-S-F)
Designed primarily to supply frequency to cellular basestations
Target output performance requirement: 16ppb frequency accuracy
Specifies frequency accuracy, noise generation, noise tolerance, holdover, testing methods

Status

Current version: 2nd. Edition, August 2017
Download from: http://www.itu.int/ITU-T/recommendations/rec.aspx?rec=13320

Key Contents

Frequency accuracy (free-run): 4.6 ppm
Noise (wander) Generation:

GdotWhat? > ITU-T G.8263 (Packet-Based Slave Clock Performance) One-Page Summary > image2019-2-22_15-55-16.png

Noise (PDV) Tolerance:

GdotWhat? > ITU-T G.8263 (Packet-Based Slave Clock Performance) One-Page Summary > image2019-2-22_15-57-43.png

Holdover: based on G.812 Type III clock (Stratum 3E)
Testing methods: Appendix I describes three methods of measuring the performance of slave clock:
- PDV patterns based on flicker noise
  Measures clock performance using input PDV containing equal energy in every decade of
  frequency (i.e. flicker noise)
- PDV patterns based on combined sinusoidal waveforms
  Measures clock performance using input PDV containing multiple frequencies simultaneously
- PDV patterns based on a single sinusoidal waveforms
  Measures clock performance using PDV containing a sinusoidal modulation of the floor delay