Technical inquiry on ON-OFF fibre optic link. |
Document: 10114
Category: 2811 / 2812 On-Off Link to Fiber Bit-Driver
Date Posted: 04/20/12 |
Problem
We are planning to use the ON-OFF fibre optic link model 2811 on a current project that we
have.
We need to send a relay status from Point A to Point C via Point B:
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STATION A
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STATION B
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STATION C
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->2811 TX------------->
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2811RX <-------> 2811 TX
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---------> 2811 RX--> |
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8KM
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B-B
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8KM |
A to B distance of fibre is 8 km using single mode fibre, ADSS 1310 nm. B to C is also 8 km.
We plan to put a 2811 TX on point A going to 2811 RX on Point B.
The Relay output of 2811 RX on Point B will be connected back to back to the relay input of another 2811 TX, this
time facing 2811 RX on Point C. This means 2 pair of 2811 will be used. Now my question is, will this work?
The data sheet I gather from your website says that the max distance is only 5 km for 1310 SM option. But that is using
a 1dB/km cable loss. The cable that we will use is spec at 0.35 dB/km. Data sheet specified as well that the optical
power budget is 10 dB. This is sufficient to cover the 8 km distance, including connector losses and splice loss
if the power budget is 10 dB, with some safety margin. Will you tell me if I am missing something here?
Solution
Link as shown will work for you and the dstance is not a problem. You actually have 10 dB budget
so you can go more than 10Km on a link. Receiver Part #2812. So you have 2811 to 2812 and then 2811 again to 2812.
You can connect back to back. we also make 2813 which is Two-way which can also be used in the middle instead of
2812 and 2811.
You are correct 1dB/KM is high.however that is loss for Multimode at 1310NM. We provide 10dB standard budget with
Multimode or Single mode (SM). So with SM Fiber, 0.35dB/KM loss you can easily go 20KM (7dB+3 dB spare budget).You
do have to allow for loss in connectors/any splices/patch panels etc. We assume your distance requirement is less
than 20KM..If not what is your loss in Link? we can increase power budget as we build our own TR/REC in 2813.
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