Extending USB cable with CAT5 cable adapters

Discussion in 'Wireless Internet' started by me here, Aug 14, 2009.

  1. me here

    me here Guest

    I'm wanting to shift a 54G dongle and attached biquad antenna about 25
    feet away from the PC.

    The options as I see it are to use:

    - two USB cables with a powered hub in the middle,

    - or USB CAT5 cable extenders to the 54G dongle.

    The questions are:

    - Which is the best option?

    - does the dongle have to be attached to a powered hub at the end of
    the CAT5 adapter to supply sufficient current?

    - am I likely to get significant signal delay with either of these

    Unfortunately for Jeff L the adapter is a Realtek.

    I am however pleased to say that it is the most effective device I've
    tried in this really bad location.

    It's one of those supposedly high power dongles off Ebay, which
    actually is "hi power" - quite amazing performance compared to my
    Belkin PCI card and a Belkin dongle I also have.

    Just for interest, the signal path goes through a double brick wall,
    past a large fridge in the next room, through two more single brick
    walls to a Belkin access point on the other side of the house.

    Not a bad effort getting 90% signal at 54G, but I have to move the
    antenna because I'm getting interference from the next door neighbours
    Apple Air Wifi immediately adjacent - even using the biquad and with
    aluminium insulation in the wall between us.

    So what's the go on the cables :)


    me here, Aug 14, 2009
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  2. me here

    Char Jackson Guest

    That would have been my suggestion, as well.
    Char Jackson, Aug 14, 2009
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  3. me here

    me here Guest

    Hadn't seen those before.

    They certainly look the way to go.

    Thanks guys.

    me here, Aug 14, 2009
  4. me here

    amdx Guest

    I used an active USB extender for my set up at one time and it worked
    fine for me. Although now I have about 20 ft of good coax
    (can't remember the #) to get into the my boat, because it is easier to
    Ok Rob, you got me wondering now, I'm on a boat, using a 15dbi flat
    panel antenna receiving a signal 300 ft to 400 ft away. Sometimes the signal
    is excellent and other times barely usable. I understand this is a two way
    and I would think the usual bottleneck would be the receive signal strength.
    So having a 500mw transmit signal would probably not help the situation.
    Is there a way to see whether the transmit or receive signal is the weak

    But this is mostly a guess on my part
    amdx, Aug 15, 2009
  5. me here

    me here Guest

    My understanding is that antenna gain is bi-directional and signal
    strength ties in accordingly.

    Check out this pdf document on the subject.


    Best laymans read I've seen.

    There are obviously a number of things that can cause changes to
    existing signal strength - which appear to be primarily related to
    external interference.


    me here, Aug 15, 2009
  6. me here

    me here Guest

    Just to elaborate on the previous post.

    The difference between the cheap Ebay Realtek adapter and the Belkin
    PCI card using the same 12 dbi biquad is a 10 - 15 % improvement in
    signal to noise with the Realtek - according to my wifi sniffer chart.

    The Realtek driver works OK under XP but its lousy under Ubuntu (Linux)
    and the Belkin is much better there = so the driver for the application
    makes a big difference.

    Also although the S/N is a lot better, I'm not totally convinced that
    the stability is as good as the Belkin, even though the signal quality
    is shown to be better.

    The upshot is that when the system is under load and the Apple Air next
    door is being used (the guy is home) you can see the device drop back
    to 48 and even 36 G at times.

    Move the antenna away from the suspected problem area and the issue
    goes away - back to 54G, so it's definitely interference in my case.

    Cheers again

    me here, Aug 15, 2009
  7. me here

    amdx Guest

    I agree about reciprocity of the antenna, my comment was about the Realtek
    with it boast of 500mw output.
    I'll check it out.
    Being on a boat is a challenge, If you have a very high gain antenna
    (very directional) you can get a strong signal but when the wind blows the
    boat shifts and misses the target. I also have a tidal range of 2 ft per day
    as much as 3.5 ft over the year.
    amdx, Aug 16, 2009
  8. me here

    amdx Guest

    I'm guessing I used 9913 with 7.5 db loss per 100 ft.
    With 20 ft of cable I calculate 1.5 db loss, throw in maybe another
    1.5db loss for the connectors and we get 3 db loss. Ya that's a loss.
    Some may call that significant, I'll call it moderate loss.
    If I get energetic I'll go back to the USB wifi adapter connected
    to the antenna with a active USB extender into the boat. and see
    if it helps.
    amdx, Aug 16, 2009
  9. me here

    amdx Guest

    Right now my software says I have a -60dbm signal strength, this is plenty
    of signal
    for my surfing. It does bounce a little from -58dbm to -68dbm. But
    mostly -60dbm.
    It also says my link speed is TX 54Mbps RX 48Mbps. This is all Good.
    I've using this for about two years a most of the time it is fine, just on a
    few days here and
    there I have trouble.
    My link is mostly across a concrete parking lot.
    amdx, Aug 16, 2009
  10. me here

    atec 7 7 Guest

    It's my understanding usb cables do have length limitations maxing out
    at around 5 metres before the beginnings or significant loss so you
    might need either a repeater and a quick google ?
    atec 7 7, Aug 16, 2009
  11. me here

    me here Guest

    What adapter/card are you using Mike?

    me here, Aug 16, 2009
  12. me here

    amdx Guest

    amdx, Aug 17, 2009
  13. me here

    me here Guest

    The transmit power on mine is supposedly 22 (+/- 1) dBm.

    54G Receive sensitivity -79 dBm

    The claims made are a bit extreme, but it certainly does a good job of
    dragging in weak signals with the 150 x 150 mm biquad (home made)


    me here, Aug 17, 2009
  14. me here

    amdx Guest

    I just did a speed test at; http://www.speed.io/index_en.html
    The results are Download 5698KBit/s Upload 377 KBit/s
    Connections 2486 and Ping 22 ms
    I don't know what it all means. I'm using the TP-link TL-WN321G
    with a 15 dbi flat panel antenna, at 300 to 400ft.
    amdx, Aug 17, 2009
  15. me here

    amdx Guest

    Interesting thought, I'll see if I can find the pattern for my antenna.
    Thanks, Mike
    amdx, Aug 19, 2009
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