Shielded RJ-45: Internal vs External Ground?

Discussion in 'Wireless Internet' started by (PeteCresswell), Jan 9, 2015.

  1. I have seen the light and am going to replace the regular Cat5 cables on
    my radio links with shielded - using Ubiquiti's ToughCable Pro.

    With shielded RJ-45 plugs, I see "Internal" and "External" as in
    Internal: http://www.platinumtools.com/products/100020.php?cat=5

    External: http://www.platinumtools.com/products/100022.php?cat=5

    For somebody who doesn't use that many - as in a hundred being a
    lifetime supply - the no-brainer would seem to be the "External" style
    because it can be used anywhere, not just with devices that
    automagically forward the ground from the shell of the connector their
    AC ground wire.

    Does this make sense? Or am I missing something.

    Ubiquiti NanoStations with POE Injectors.
     
    (PeteCresswell), Jan 9, 2015
    #1
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  2. (PeteCresswell)

    Char Jackson Guest

    I'm curious, where is this discussion taking place where they're
    recommending shielded cable? I wonder what's the basis for the
    recommendation. Yes, I'm skeptical.
     
    Char Jackson, Jan 10, 2015
    #2
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  3. Per Char Jackson:
    So was I.

    But the manual says that shielded cable is important. viz Page 4 of
    http://setuprouter.com/router/ubiquiti/nanostation-m5/manual-877.pdf

    Self-serving promo for their house brand? That was my kneejerk
    reaction.... but now I know that there are several threads in the
    Ubiquiti fora that make it pretty clear that electrostatic discharge is
    a consideration. For example: http://tinyurl.com/m5vttf3

    Now I realize that I cannot afford to be skeptical because I just don't
    know enough.

    The facts are:

    - Every so often 3 cams become unreachable from a remote site over
    a radio link.

    - A fourth cam never, ever has any problems

    - The 3 problem cams immediately become reachable once both
    ends of the radio link are re-booted.

    - One of the links is attached to the top of a 15-foot windsurfer
    mast only about 50' from a large bay - i.e. it gets some
    serious weather.

    Add to the above that it is starting to look like there is a correlation
    between the failures and high winds at the site and you see where I
    am....

    But, like I said, I'm clueless except that I know that those three
    things are clearly happening.... And the pros on the Ubiquiti site are
    telling me that grounded/shielded cable to an outside radio is
    absolutely standard practice.

    I have withdrawn from the discussion where this is taking place because
    I was starting to irritate at least one of the gurus there with my
    incessant beginner-type questions. The guys who matter there are
    mostly professionals and it is now clear to me that I was abusing the
    environment. There are also amateurs there, but I seem to be more
    verbose and less inclined to research before asking than most.

    But my basic question remains: how can a radio-link problem be
    camera-specific?

    Greater Minds Than Mine have said "No problem... see it all the time."

    But I have yet to get specifics... to that end, I just pulled the
    trigger on a smart switch that I will swap in down at the problem site
    when I get down that way. Then I will be able to test the obvious
    suggestion that it is something to do with bandwidth (not!...but I need
    to prove it) and also to put WireShark on both ends of the link.

    Whatever happens, I am going to come out of this knowing significantly
    more than when I went in.

    The thread is at: http://tinyurl.com/m6pyfje
     
    (PeteCresswell), Jan 10, 2015
    #3
  4. Just a pure guess, but if the wind is that bad at the remote site I
    wonder if the power might not be fluctuating for the same reason.
    With the three affected cameras being from the same brand I wonder if
    that brand might be more sensitive to the fluctuations.

    If you have a small UPS handy you might want to plug the switch into it
    and see if the problem goes away since it is powering all the cameras at
    the site.
     
    GlowingBlueMist, Jan 10, 2015
    #4
  5. Static buildup on metal structures is only a problem when the humidity
    is quite low. My guess(tm) is 20% or less. That's not a problem in
    the bay area, and certainly not in a wet marine environment.

    Shielding does do well for EMI/RFI protection. If you're near a
    transmitter of any significant power level, I would use shielded
    cable. Even so, I doubt if it would do any good because most of the
    Ubiquiti radios use unshielded plastic case.

    Note that there are aftermarket products that provide shielding if
    needed.
    <http://www.rfelements.com/en/products/shields/rockshield/>
    If you're using it for cellular backhaul, it's probably a good idea.
     
    Jeff Liebermann, Jan 10, 2015
    #5
  6. One more:
    <http://www.rfarmor.com>
    Notice that the listed reasons for installing shielding do not mention
    precipitation static, or air friction static buildup. If you're going
    to shield the CAT5, might was well shield everything else (except the
    antenna).

    Maybe try aluminum duct tape on the inside of the plastic case for
    cheap shielding?
     
    Jeff Liebermann, Jan 10, 2015
    #6
  7. Per GlowingBlueMist:
    I think I have disposed of the wind theory. It developed when I saw
    several failures in a few hours when the wind was gusting into the
    forties. But yesterday I had more instances when there was just
    normal wind.

    I'll take the UPS suggestion though...
     
    (PeteCresswell), Jan 11, 2015
    #7
  8. (PeteCresswell)

    ps56k Guest

    X-posting to the Cabling newsgroups
     
    ps56k, Jan 13, 2015
    #8
  9. (PeteCresswell)

    ps56k Guest

    X-posting to Cabling newsgroups

     
    ps56k, Jan 13, 2015
    #9
  10. (PeteCresswell)

    ps56k Guest

    X-posting - for those in the Cabling world -

     
    ps56k, Jan 13, 2015
    #10
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