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Single mode fibre query

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  • 25-06-2010 3:36pm
    #1
    Paddyo
    Registered Users Posts: 414 ✭✭


    Hi All

    I am no expert on fibre connections and hope that someone out there is.

    First question, is single mode the same as single strand?

    If someone is looking for single mode, should they use dual ior single connector modules

    Many thanks for any help
    Paddyo


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    #2
    Snaga
    Registered Users Posts: 1,562 ✭✭✭Snaga


    No - it has nothing to do with the number of fibers in the cable.

    Without going into major detail - single mode can be thought of as having a much smaller diameter core than Multimode. I know its hard to tell looking at them from the outside, but under a microscope the differences are huge! (If you squint at it you might be able to tell the difference between them).

    Multimode is used for shorter distances (cheaper to manufacture both the cable and the optics as they can use lower frequency light and do not need to be as precise) while single mode can be used for short, medium or long runs (120km+ if youve got the optics) - but is generally more expensive.

    You find Multimode being used a lot (but not exclusively) for connecting things inside buildings on short runs, but any fiber in the ground would usually (99%+) be singlemode.

    Most networking equipment use 2 strands for Full Duplex communication - a single strand for the transmit signal and a second single strand for the receive signal.

    Some equipment though can use one wavelenght of light for transmitting and a seperate wavelenght for receiving - allowing the use of a single strand for full duplex transmission with no interference. This tends to be in the minority and generally only in a service provider type situation.

    The best bet is to simple ask the person that needs it (1) what fiber type they want (single mode or multi mode), (2) what connectors they want (These are many and varied!) and (3) if they need a full duplex cable (chances are this will be a yes).

    The answer to each of these will depend on the equipment they are using - so they should be able to tell you.

    There are a list of some common connectors here...

    http://en.wikipedia.org/wiki/Optical_fiber_connector

    LC and SC would be the most common connector types in the enterprise area. (LC connectors for SFP optics and SC connectors for GBIC optics).


  • Options
    #3
    Paddyo
    Registered Users Posts: 414 ✭✭Paddyo


    Many Thanks Snaga

    I think it will be the Dual connectors

    Regards
    Paddyo


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