Specialized inspection for SDH optical interfaces is carried out in accordance with standards including TB 10755-2018. Key metrics such as allowable frequency offset at the optical input port, average transmitted optical power, receiver reflection coefficient, minimum receiver overload power and receiver sensitivity are covered in the inspection. With precision optical testing instruments, the signal transmission quality and compatibility of optical interfaces can be evaluated, normal optical signal interaction between SDH devices can be guaranteed, and stable optical interface performance can be supported for high-speed railway communication projects, telecommunication networks and other scenarios.
Inspection Items
Allowable frequency offset at optical input port, average transmitted optical power, receiver reflection coefficient, minimum receiver overload power, receiver sensitivity, received optical power, maximum -20 dB spectral width (σ₋₂₀), maximum RMS spectral width (σᵣₘₛ), minimum side mode suppression ratio (SMSR), laser operating wavelength, AIS rate at optical output port, optical path penalty, optical path attenuation, receiver overload power
Inspection Standards
1. TB 10755-2018 Standard for Construction Quality Acceptance of High-speed Railway Communication Engineering
2. GB 50382-2016 Code for Quality Acceptance of Urban Rail Transit Communication Engineering
3. GB/T 15941-2008 Access Requirements for Synchronous Digital Hierarchy (SDH) Optical Cable Line Systems, Clause 8.3.3.2
4. GB/T 16814-2008 Test Methods for Synchronous Digital Hierarchy (SDH) Optical Cable Line Systems, Clause 6.18
5. GB/T 20185-2006 Technical Requirements for Optical Interfaces of Synchronous Digital Hierarchy Equipment and Systems
6. TB 10418-2018 Standard for Construction Quality Acceptance of Railway Communication Engineering
7. GB/T 15941-2008 Access Requirements for Synchronous Digital Hierarchy (SDH) Optical Cable Line Systems
8. GB/T 16814-2008 Test Methods for Synchronous Digital Hierarchy (SDH) Optical Cable Line Systems
9. GB/T 20185-2006 Technical Requirements for Optical Interfaces of Synchronous Digital Hierarchy Equipment and Systems, Clause 8.28.3
10. GB 50382-2016 Code for Quality Acceptance of Urban Rail Transit Communication Engineering, Clause 8.2.2
11. TB 10418-2018 Standard for Construction Quality Acceptance of Railway Communication Engineering, Clause 6.3.1
12. TB 10755-2018 Standard for Construction Quality Acceptance of High-speed Railway Communication Engineering, Clause 6.3.1
13. YD/T 1276-2003 Test Methods for SDH-based Multi-service Transport Nodes, Clause 5.1.11
14. ITU-T G.707/Y.1322:2016 Network node interface for the synchronous digital hierarchy (SDH)
15. ITU-T G.783:2016 Characteristics of synchronous digital hierarchy (SDH) equipment functional blocks
Inspection Equipment
Optical interface tester, optical power meter, optical spectrum analyzer, reflection coefficient tester, bit error ratio tester, optical frequency offset meter, optical attenuator
Key Indicators and Inspection Requirements
1. Optical power: deviation ≤±0.5dBm
2. Receiver sensitivity: ≤-28dBm (BER=1×10⁻¹²)
3. Bit error ratio: ≤1×10⁻¹²
4. Jitter: input ≥0.1UI, output ≤0.05UI
5. Protection switching time: ≤50ms
6. Alarm function: accurate reporting without missing or false alarms
Inspection Methods and Implementation Points
1. Inspection is conducted in compliance with YD/T 1097-2018
2. Optical power test: operating wavelength is measured with an optical power meter
3. Bit error ratio test: a 24‑hour continuous run is performed via an SDH analyzer
4. Jitter test: measurement is completed using a jitter analyzer
5. Protection switching test: switching duration is recorded under simulated fault scenarios
6. Alarm verification: alarm reporting logic is checked through fault simulation
Precautions
1. Testing starts only when the equipment has no active fault alarms
2. Optical interfaces need cleaning before connection
3. All testing instruments must stay within valid calibration cycles
4. Testing should be arranged outside business peak hours
5. Complete service configuration backup prior to inspection
6. Keep test cable connections tight and stable
Note: All information above is for reference only. For further details and customized inspection solutions, please contact us at any time.
