Low signal quality

Archived from groups: alt.internet.wireless (More info?)

On occasions I terminate end user DSL with WLAN bundling. The clients
usually get's the cheapest wireless devices they can find and around these
parts that is Topcom. I'm experiening that the signal strenght is extremely
low in scenarios where the AP is only a few meters away from
the client NIC. This is somethimes occuring on Dlink equipment aswell. All
the while I have excellent signal strengt from the same location with
my Linksys PCMCIA NIC.

Does anyone have an idea why this is occuring? Is there some hardware I can
use to test wireless connections?
2 answers Last reply
More about signal quality
  1. Archived from groups: alt.internet.wireless (More info?)

    On Thu, 07 Oct 2004 04:05:40 -0500, Tomas Pedersen <tp@yahoo.com>
    wrote:

    >On occasions I terminate end user DSL with WLAN bundling. The clients
    >usually get's the cheapest wireless devices they can find and around these
    >parts that is Topcom. I'm experiening that the signal strenght is extremely
    >low in scenarios where the AP is only a few meters away from
    >the client NIC. This is somethimes occuring on Dlink equipment aswell. All
    >the while I have excellent signal strengt from the same location with
    >my Linksys PCMCIA NIC.
    >
    >Does anyone have an idea why this is occuring? Is there some hardware I can
    >use to test wireless connections?

    Which Topcom product(s)? Are both the wireless router and client
    radios made by Topcom?

    http://www.topcom.net/products/index.php#WIRELESS%20NETWORKING%20PRODUCTS
    Which DLink equipment? Wireless router or client radio?

    Topcom does NOT show up on the FCC ID search page. I'm trying to
    determine who made the products, what chipset is used, and at what
    power level they qualified for type certification. If you have the
    FCC ID number from the serial number tag, it would be a big help.

    I don't have an instant answer to why a particular brand has signal
    strength problems. However, I've seen a wide variety of designed in
    ways to screw up signal strength. Grossly inefficient antennas, long
    lossy circuit board traces, poor quality circuit boards, dirty boards,
    high VSWR board to antenna interfaces, variations on voltage
    regulators, and defective firmware settings.

    There are some Xmit signal strength testers available. Note that
    measureing the TX signal strength is only half the equation. You also
    need to measure the receive sensitivity, which is also capable of
    limiting the range. Without a big budget pile of test equipment, this
    is a non-trivial test. I'll limit my suggestions to TX power. I
    assume that you want something other than an RSSI indication from a
    "known good" wireless card.

    1. Dedicated 802.11 tester $1500:
    http://www.bvsystems.com/Products/WLAN/Grasshopper/grasshopper.htm

    2. Cheapo WLAN tester made from a Symbol FHSS DPA. $150. I just
    ordered one. (I couldn't resist)
    http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=5724414084

    3. Spectrum analyzer test card. I can't find it, but it uses a
    Proxim RangeLAN2 7400 series FHSS card. $25-30.

    http://www.e3.com.au/modules.php?op=modload&name=News&file=article&sid=22

    4. Digital microwave oven leakage detector. $35.
    http://www.comforthouse.com/comfort/micleakdetwi.html
    I butchered one by replacing the detector diode and adding an external
    dipole antenna to the detector:

    http://www.LearnByDestroying.com/pics/Microwave%20Leakage%20Detector/index.html
    Oops. I don't have the butchered version posted. Anyway, I can
    measure 2.4GHz field stength about 3 meters away.

    5. Real spectrum analyzer. Avcom is about as cheap as it gets:
    http://www.avcomofva.com
    There's no upper limit on what you can spend on a spectrum analyzer.

    Customers ringing....gone.

    --
    Jeff Liebermann jeffl@comix.santa-cruz.ca.us
    150 Felker St #D http://www.LearnByDestroying.com
    Santa Cruz CA 95060 AE6KS 831-336-2558
  2. Archived from groups: alt.internet.wireless (More info?)

    Jeff Liebermann <jeffl@comix.santa-cruz.ca.us> wrote:
    >2. Cheapo WLAN tester made from a Symbol FHSS DPA. $150. I just
    >ordered one. (I couldn't resist)
    > http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=5724414084

    Let us know when you get it how well it works, that looks very
    interesting!
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