Enhanced synchronization device slave clock technical requirements
1Key Takeaways
This document applies to the development and production of Packet Transport Network (PTN) equipment, Sliced Packet Network (SPN) equipment and Optical Transport Network (OTN) equipment using enhanced synchronization equipment slave clocks.
2Expert Interpretation
An in-depth interpretation of the technical requirements for enhanced synchronization equipment slave clock (eSEC) in the YD/T standard, covering core indicators such as noise generation/tolerance/transfer characteristics, transient response, interface specifications, etc., suitable for synchronization system design and test verification of transmission equipment such as PTN/SPN/OTN.
Analysis of Standard Technical Framework
| Core Indicators | First-level Performance Requirements | Second-level Performance Requirements |
|---|---|---|
| Drift Tolerance MTIE | 10τ0.155 ns (0.1≤τ≤1s) | 250ns (0.1<τ≤2.5s) |
| Frequency Accuracy | ±4.6ppm (Free Oscillation) | |
| Phase Transient Response | φ(t)=2c+1×10-8t (c≤10ns) | |
Key Technical Requirements
Noise Generation Characteristics
When eSEC locks the ideal reference source, under constant temperature conditions, the following conditions must be met:
- MTIE: Increase by 10τ0.155 from 0.1 to 1s, and do not exceed 6.3τ0.2 in 1000s>
- TDEV: Maintain 0.64ns from 0.1 to 25s, and do not exceed 1.28ns in 1000s
Typical application scenarios: class=instrument>SPN device clock module needs to pass the jitter generation test of ≤1.5UI (1GbE interface)
Networking architecture requirements
The standard specifies two networking modes:
- Pure eSEC cascade: up to 20 hops, suitable for high-precision time synchronization networks
- Hybrid networking: compatible with traditional SEC/EEC, but must meet the secondary drift tolerance
Implementation points: the number of clocks connected in series between nodes is ≤20, and the entire chain does not exceed 60
Implementation recommendations
Test verification plan
| Test items | Reference standards | Key equipment |
|---|---|---|
| Jitter tolerance | ITU-T G.8262.1 | ≥10 times the accuracy of the clock source |
| Hold performance | Formula (4) | Constant temperature box (±1K) |
Typical problem: The phase jump time parameter T of the OTN interface needs to be determined according to the actual filtering bandwidth of the device. It is recommended to verify it through the back-to-back test method in Appendix B