Insertion Loss get grades of A, B, C, etc.
| Table 2 – Single Mode attenuation grades at 1310nm and 1550nm (dB) | |||
| Attenuation grade | Attenuation (≥ 97%)a | Mean | Notes |
| A | Reserved for future application | ||
| B | ≤ 0.25 | ≤ 0.12 | |
| C | ≤ 0.50 | ≤ 0.25 | |
| D | ≤ 1.0 | ≤ 0.50 | |
The probability of a random mated connector set of meeting or exceeding the specific level of attenuation will be ≥ 97%. This performance is reached considering a statistical distribution of connector’s parameters (MFD, eccentricity and tilt angle) and using a nominal value for wavelength.
Return Loss get grades of 1, 2, 3, etc.
| Table 3 – Single Mode Return Loss grades at 1310nm and 1550nm (dB) | ||
| Return Loss grade | Return Loss (≥ 97%)a | Notes |
| 1 | ≥ 60 | ≥ 55dB in unmated condition (APC only) |
| 2 | ≥ 45 | |
| 3 | ≥ 35 | |
| 4 | ≥ 26 | |
Reference Grade Connectors
IEC 61755-2-4, 61755-2-5
| Table 1 – Single Mode attenuation grades at 1310nm | ||
| Reference grade a | Attenuation a dB | Contribution to measurement uncertainty b dB |
| R1 | ≤ 0.1 | ± 0.1 |
| R2 | ≤ 0.2 | ± 0.2 |
a Under the assumption of worst case alignment with identical connector plug. Expected attenuation measured when connecting two plugs of the same grade may be higher due to significant measurement uncertainty.
b As described in Clause 8.
