RFSDH Hierarchy: STM Levels and Bit Rates Explained
sdh
synchronous digital hierarchy
bit rate
stm
optical communication
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This article explains the Synchronous Digital Hierarchy (SDH) and its different levels, including STM-0, STM-1, STM-4, STM-16, STM-64, and STM-256, focusing on their bit rates and their relationship with E1 and E4 carrier systems.
SDH Terminology and Bit Rates
The following table outlines the various SDH terms, their corresponding bit rates, abbreviated bit rates, and SDH capacity in terms of E1 and E4 channels.
| SDH Terminology | Bit rate | Abbreviated bit rate | SDH capacity |
|---|---|---|---|
| STM-0 | 51.84 Mbits/sec | 51 Mbps | 21 E1 |
| STM-1 | 155.52 Mbits/sec | 155 Mbps | 63 E1 or 1 E4 |
| STM-4 | 622.08 Mbits/sec | 622 Mbps | 252 E1 or 4 E4 |
| STM-16 | 2488.32 Mbits/sec | 2.4 Gbps | 1008 E1 or 16 E4 |
| STM-64 | 9953.28 Mbits/sec | 10 Gbps | 4032 E1 or 64 E4 |
| STM-256 | 39813.12 Mbits/sec | 40 Gbps | 16128 E1 or 256 E4 |
