ITU-T G.8273.3 (T-TC) One-Page Summary

Title: Timing characteristics of Telecom Transparent Clocks (T-TC)

Summary

  • Clock specification for T-TC (transparent clock) for full timing support architecture, including noise tolerance, noise generation, noise transfer, phase transients

  • Two clock types defined, classes A and B

    • Class A intended for short chains (up to 10 clocks), to meet ±1.5µs overall requirement

    • Class B intended for long chains (up to 20 clocks), to meet ±1.5µs overall requirement

  • T-TCs are considered a direct replacement for T-BCs in the full timing support architecture, provided the T-TCs comprise no more than eight clocks in the overall chain (as per II.2.1 of G.8271.1)

Status

Key Contents

Noise Generation:

Parameter

Conditions

Class A

Class B

Max |TE|

Unfiltered, 1000s

100ns

70ns

Max|TEL|

0.1Hz low-pass filter,1000s

-

-

cTE

Averaged over 1000s

50ns

20ns

dTEL MTIE

0.1Hz low-pass filter, Const. temp, 1000s

40ns

40ns


0.1Hz low-pass filter, Var. temp, 10000s

40ns

40ns

dTEL TDEV

0.1Hz low-pass filter, Const. temp, 1000s

4ns

4ns

dTEH

0.1Hz high-pass filter, Const. temp, 1000s

70ns

70ns

Transfer Function:

  • No filtering of noise from PTP input to output
  • Low-pass filtering of noise on physical layer frequency input, bandwidth between 1 and 10Hz

Holdover:

  • No holdover provided by a T-TC

Simplified Functional Model:


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