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Cable tester

Discussion in 'Electronic Design' started by [email protected], Jan 31, 2008.

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  1. Guest

    Has anyone created a Cat5 / utp/ ethernet /lan cable tester that more
    than just a simple led light chaser?

    Cheers
    Steve
     
  2. Joel Koltner

    Joel Koltner Guest

  3. Guest

    Thanks for the links..

    My question is has anyone CREATED one.. not simply bought one from a
    store.

    I would like to build my own. guess I should have been more specific
    =)

    Cheers
    Steve
     
  4. Joel Koltner

    Joel Koltner Guest

    "I would like to build my own. guess I should have been more specific"

    You can begin by telling us... what would you like it to do?
     
  5. How about a poor mans TDR?
     
  6. Ecnerwal

    Ecnerwal Guest

    That would be good - in the mode of creature feep, a bnc connector would
    be nice with the TDR as well (got a 250 footer that's gone bad
    somewhere, but it's tie-wrapped to stuff here, in conduit there, and I
    can't find it by inspection - though I'm probably just going to yank it
    out as I already worked around it).

    Mind you, I think the only "affordable" way to do TDR is if the poor man
    already has an oscilloscope, and can drag it to the cable with a pulse
    generator - but I'm willing to find out differently.

    *** (not novel)
    Cable ID (rabbit and ferret) - two boxes, one has signal injection and
    the other can pick out the cable with that signal from the other N
    unlabeled cables stuffed into some dank nasty part of a building. Signal
    should not damage ethernet or phone devices if other end of cable is
    plugged in.

    *** (not novel)
    End-to-end check - the second box can also plug into the far end and
    make some sort of check on the cable with both ends far apart, as when
    installed. Ideally this would be adaptive (ie, if one side of a pair is
    broken, but some other wire goes through, the tester pairs up to find as
    many good wires as possible, down to the logical lower limit of 2 wires)

    *** (might be slightly novel, or I don't look at enough test equipment I
    can't afford)

    Once end-to-end check passes (at least for a couple of pairs), do some
    end to end test patterns, ideally at various data rates, ideally
    including rates exceeding the nominal operating rates for the sake of
    peace of mind, or marginal link detection, or whatever you want to call
    it.

    ie, for Ethernet, run tests at 10BaseT speed, and 12 and 15 (not that
    those exist) and 100 BaseT speed, and 120 and 150 (not that they exist),
    and 1000 BaseT, and 1200 and 1500 (not that they exist)

    ....and we've probably passed right out of affordable, poor man territory
    again.

    ***
    For completeness, get a couple of surplus cell-phone vibrator things,
    and switch those on at some point in the testing (in both boxes, perhaps
    one at a time) to see if the connectors are flaky with motion.
     
  7. check out: http://www.epanorama.net/circuits/tdr.html

    Now here's a question. I need to design a system to determine the
    characteristics of a cable, impedance, cross-talk, etc.. Buying one is
    not practical, since I am in Zimbabwe... Anyone got some good links
    to information? Useful advice?
     
  8. Also consider some sort of crosstalk test between the various twisted
    pairs.

    One of the most common errors in making up Cat5 cables is to mix up the
    various paired conductors. Continuity will check out OK, and perhaps
    even unidirectional data transmission. But the signals will be coupled
    into adjacent conductors to a higher degree.
     
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