PLC splitter ratios and the GPON loss budget: a worked example
How to check whether a 1×32 or 1×64 split fits your GPON optical budget: splitter loss, fiber, connectors and splices added up, with a worked example and the class B+ and C+ limits.
The budget in one line
A GPON link works when fiber loss + splitter loss + connector loss + splice loss + margin stays within the optical budget of the OLT and ONT optics. Class B+ optics give 28 dB; class C+ give 32 dB.
Typical loss values
| Item | Typical value used for planning |
|---|---|
| Fiber at 1310 nm | 0.35 dB per km |
| Fiber at 1490 nm | 0.25–0.30 dB per km |
| Mated connector | 0.3 dB each |
| Fusion splice | 0.1 dB each |
| PLC splitter 1×8 / 1×16 / 1×32 / 1×64 | 10.5 / 13.8 / 17.1 / 20.5 dB (typical maxima) |
Worked example: 20 km, 1×32
| Item | Loss |
|---|---|
| 20 km of G.652.D at 1310 nm | 7.0 dB |
| 1×32 PLC splitter | 17.1 dB |
| 4 mated connectors | 1.2 dB |
| 10 splices | 1.0 dB |
| Total | 26.3 dB |
Against class B+ (28 dB) that leaves 1.7 dB of margin, which is thin once repairs, ageing and dirty connectors are counted. Common fixes:
- Use class C+ optics (32 dB), which leaves almost 6 dB of margin.
- Shorten the longest feeder runs, or move the split closer to the homes.
- Use 1×16 where distances are long and 1×32 or 1×64 where they are short.
Order splitters with measured values
Every PLC splitter we supply ships with insertion loss measured on each port, so you plan with the real numbers rather than the maximum. See ODN and FTTx components and PON optics.
Next guide MPO polarity explained: Methods A, B and C