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differential or single ended outputs

Discussion in 'EthConGateway by Joshua 1 Systems' started by Porsche, Dec 15, 2014.

  1. Porsche

    Porsche Full Time Elf

    Nov 7, 2012
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    Perth, Piara Waters
    Hold on everyone, heres another dumb question coming your way!!!!
    But im sure there's a few of us out there that may not know this answer. especially not tech savvy ones like myself.

    what's the definition of a differential output or single ended?

    All ive been using in my display are the P2's but looking at the P12 options, obviously they have these options and I need to get my head around them.

  2. viennaxmas

    viennaxmas New Elf

    Sep 6, 2012
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    Differential uses two wires for data and two for clocks. The signal on one of the wires is reversed to the other wire. The purpose for this circuitry is to eliminate interference. In case interference does get into the wire, it is in phase on both wires. The receiver inverts one of the signals, therefore the interference is in phase on one and reversed on the other wire. If you combine the two signals, the interference is therefore eliminated. The intended signal does get a higher amplitude but is clear.

    On a single wire (SGL) you do not have the ability to filter interference and therefor your pixels go crazy if the distance is too long.

    Differential signals are widely used: balanced Audio, control signals for machines and cars (CAN bus) and the DMX / LOR protocols.

    In addition the circuitry on the differential outputs is optimized for long distances.

    As an example: I have one P12D for the entire back yard. It drives 4 strings directly via SGL out and 8 via pixel extenders with distances between 50 and 150 ft. With a conventional SGL setup this would have required 6 controllers due to location of the pixel strips. The extenders are just a lot cheaper to do the same.

    I'll still add a few more P12D next year ;-)

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