- 2075 Asoj (CS II) · 4 marks
Differences between T1 and E1 hierarchy
Short answer
T1 uses 24 channels at 1.544 Mb/s with µ-law companding and robbed-bit signaling. E1 uses 30 channels at 2.048 Mb/s with A-law and a dedicated signalling slot TS16.
Explain the differences between T1 and E1 digital hierarchy.
T1 and E1 are TDM-PCM digital carrier systems. Both use 8 kHz sampling, 8-bit samples and 125 µs frames, but they differ in channel count, framing and rates.
| Point | T1 (North America, Japan) | E1 (Europe, ITU-T, Nepal) |
|---|---|---|
| Voice channels | 24 | 30 (+2 overhead slots) |
| Time slots per frame | 24 + 1 framing bit | 32 |
| Bits per frame | ||
| Frame duration | 125 µs | 125 µs |
| Bit rate | 1.544 Mb/s | 2.048 Mb/s |
| Framing | 1 F-bit per frame, pattern over 12/24 frames | TS0 carries frame alignment word |
| Signalling | Robbed-bit (LSB of frames 6 and 12) | Separate slot TS16 (CAS) |
| Multiframe | Superframe 12 frames / ESF 24 frames | 16 frames (2 ms) |
| Companding law | µ-law, | A-law, |
| Line code | AMI / B8ZS | HDB3 |
| Higher levels | 6.312, 44.736, 274.176 Mb/s | 8.448, 34.368, 139.264, 564.992 Mb/s |
✓ Answer checked by Claude Opus 5.5 (high effort)
Related questions
- Short note: T1 and E1 hierarchy · Communication Systems, chapter 5
- FDMA vs TDMA; T1 and E1 hierarchy · Communication Systems, chapter 5
- T1 and E1 TDM-PCM hierarchy with frame diagrams · Communication Systems, chapter 5
- E1 digital hierarchy; SQNR in uniformly quantized PCM · Communication Systems, chapter 5 · asked 2×
- Short note: E1 digital hierarchy · Communication Systems, chapter 5
- Constellation diagram significance; E1 vs T1 · Communication Systems, chapter 5
- North American T1 vs European E1 hierarchy · Telecommunications, chapter 3 · asked 2×
- T1 and E1 frame structures and bit rates · Telecommunications, chapter 3
- TDM and T1/E1 carrier standards · Telecommunications, chapter 3
- E1 telephone hierarchy · Computer Networks and Security, chapter 2