How to calculate optical fiber attenuation

Total attenuation accounting of optical fiber attenuation 1 ODN

According to the worst value method of transmission index accounting, the transmission distance between EPON OLT-ONU ONU ONU should satisfy the following formula:

Optical fiber attenuation coefficient * transmission distance+insertion loss of optical splitter+number of movable connectors * loss+attenuation margin of optical cable line ≤ maximum allowable attenuation at EPON R/S-S/R point.

2 EPON R/S-S/R attenuation range:

The optical power of OLT PON port is 2dB~7dBm, and the sensitivity of receiving light is -27dBm.

The optical power of ONU is-1dBm~4dBm, and the optical sensitivity of ONU is -24dBm.

Considering the optical channel cost of 1dB, the maximum allowable attenuation between R/S-S/R of EPON system is:

Uplink (ONU-OLT, 13 10 nautical mile): 25 dB.

Downlink (OLT-ONU, 1490 nautical mile): 25 dB.

3 attenuation coefficient of optical fiber (including fixed fusion loss):

Uplink (ONU-OLT, 13 10 nautical mile): 0.4 dB/km.

Downlink (OLT-ONU, 1490 nautical mile): 0.3 dB/km.

4 Typical values of insertion loss of splitter (even splitter, excluding connector loss) are shown in the following table:

Insertion loss of model specification (dB)

FBT 1x2 ≤3.6

FBT 1x4 ≤7.3

PLC 1x8 ≤ 10.7

PLC 1x 16 ≤ 14.0

PLC 1x32 ≤ 17.4

PLC 1x64 ≤2 1.6

Loss of movable joints: the connection loss of each movable joint is 0.5dB.

6 optical cable line redundancy:

Transmission distance ≤5km, take 2dB.

Transmission distance ≤ 10km, 2~3dB.

Transmission distance >; 10km, 3dB.

Considering the above factors comprehensively, the transmittable distance between OLT-ONU-ONU is obtained.

Optical fiber attenuation: 0.36 dB /km at the wavelength of 13 10nm.

Splitter insertion attenuation value: 1:64. Optical splitters need 14.0 dB.

The serial number is called the attenuation value per unit quantity (dB)

1 optical cable km 1.00 0.36

2 optically active connectors 6 3.0

3 1:64 optical splitter 1 14

4. The redundant kilometers of optical cable lines are less than or equal to 10 square kilometers.

5 Total DB- 19.36

Note: the attenuation value of optical cable is based on the attenuation value of optical cable length in direction A and the attenuation value in direction B..