SDH Transmission Equipment Testing

Full-performance inspection for SDH transmission equipment is implemented following standards including GB/T 15941-2008. Systematic checks are carried out on core parameters such as protection switching time, spectral characteristics, return loss, jitter, receiver overload power, extinction ratio, eye diagram, bit error and average transmitted optical power. Relevant testing verifies the transmission performance and stability of SDH devices in communication networks, supports high-quality signal transmission, and meets technical specifications for transmission equipment used by telecom carriers and enterprise communication networks.

Inspection Items

Protection switching time, spectral characteristics, return loss, jitter, receiver overload power, extinction ratio, eye diagram, bit error, average transmitted optical power, receiver sensitivity

Inspection Standards

1. GB/T 15941-2008 Access Requirements for Synchronous Digital Hierarchy (SDH) Optical Cable Line Systems

2. GB/T 15941-2008 Access Requirements for Synchronous Digital Hierarchy (SDH) Optical Cable Line Systems, Clause 11.1.4

3. ITU-T G.707/Y.1322:2016 Network node interface for the synchronous digital hierarchy (SDH)

4. ITU-T G.783:2016 Characteristics of synchronous digital hierarchy (SDH) equipment functional blocks

Inspection Equipment

SDH transmission analyzer, optical spectrum analyzer, return loss tester, jitter analyzer, optical power meter, eye pattern tester, bit error rate tester, signal generator

Key Indicators and Inspection Requirements

1. Optical power: deviation ≤±0.5dBm

2. Receiver sensitivity: ≤-28dBm (BER=1e-12)

3. Bit error rate: ≤1e-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 rate 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