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Loss Budget
The Fiber Optic Transmission System is made up of three components:
- Transmitters
- Receivers
- The Interconnect
Transmitters have a measured optical output power, while receivers are measured in sensitivity. To calculate the system gain or loss budget, simply subtract the receiver sensitivity from the transmitter average output power. We have calculated this number for you and listed it on our product sheets under Optical Loss Budget. This is the maximum allowable loss between a transmitter and receiver. The system loss budget must be adjusted for several factors. These include:
- Operating margin
- Repair margin
The operating margin allows for conditions of temperature change and component aging. The repair margin accounts for any potential damage that a cable may incur. American Fibertek recommends that 3dB of system margin be left to cover any of these circumstances.
The interconnection consists of the fiber optic cable, connectors and any splices that are required to complete a fiber system installation. Standard cable attenuation is published as part of the performance specifications of cable. Connector losses for systems planning may vary by connector type. Typically, we strongly recommend the ST type connector for multimode and the FC/PC type connector for singlemode.
Splices may vary according to the type chosen. The lowest loss would be incurred using a fusion splice. A good one is almost transparent. The highest loss would be experienced when two connectors are mated in a passive coupler. Coupler loss can exceed the 1dB range. Please see the following chart on Loss Budget Parameters:
| Fiber |
850 nm |
1300 nm |
1550nm |
| Multimode |
3.0 dB/Km |
1.0 dB/Km |
1.0 dB/Km |
| Singlemode |
0.4 dB/Km |
0.3 dB/Km |
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| Splices |
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| Passive Coupler |
1.0 dB |
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| Mechanical |
0.5 dB |
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| Fusion |
<0.2 dB |
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| Connectors |
0.5 dB |
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