signal strength, link quality; interference

my pcmcia card software reports "signal strength" and "link quality" but
I think this does not take into account interference and other variables
that effect overall throughput. It also shows transfer speed, in
mb/sec?, but this is highly variable and changes constantly. What can I
use to better test each antenna I make and to properly aim it for
optimal throughput? I know, I know, someone is going to say you're
asking the wrong/dumb question or not providing enough info, right? OS
is 98se. card is, I think orinoco.

"listening" <(E-Mail Removed)> wrote in message
news:gkogq0$er6$(E-Mail Removed)...
> my pcmcia card software reports "signal strength" and "link quality" but
> I think this does not take into account interference and other variables
> that effect overall throughput. It also shows transfer speed, in
> mb/sec?, but this is highly variable and changes constantly. What can I
> use to better test each antenna I make and to properly aim it for
> optimal throughput? I know, I know, someone is going to say you're
> asking the wrong/dumb question or not providing enough info, right? OS
> is 98se. card is, I think orinoco.

try Netstumbler - if it supports your cards chipset -
has a nice moving graph for each SSID that it detects.

On 16 Jan, 02:18, Jeff Liebermann <je...@cruzio.com> wrote:
> On Thu, 15 Jan 2009 18:20:01 -0600, "ps56k"
>
> <pschuman_no_spam...@interserv.com> wrote:
>
> >"listening" <listen...@echelon.gov> wrote in message
> >news:gkogq0$er6$(E-Mail Removed)...
> >> my pcmcia card software reports "signal strength" and "link quality" but
> >> I think this does not take into account interference and other variables
> >> that effect overall throughput. It also shows transfer speed, in
> >> mb/sec?, but this is highly variable and changes constantly. What can I
> >> use to better test each antenna I make and to properly aim it for
> >> optimal throughput? I know, I know, someone is going to say you're
> >> asking the wrong/dumb question or not providing enough info, right? OS
> >> is 98se. card is, I think orinoco.
>
> >try Netstumbler - if it supports your cards chipset -
> >has a nice moving graph for each SSID that it detects.
>
> Agreed. *However, the current version of Netstumbler (0.4.0) does not
> exactly work with Windoze 98se. *It works only if you have the
> original Hermes chipset based Orinoco Gold or Silver PCMCIA card, also
> known as Orinoco "classic". *However, the previous version (0.3.30)
> works just fine but has a few bugs that were fixed in 0.4.0. *Avoid
> 0.3.23.
>
> Since you're into antique hardware and operating systems, this might
> be of interest:
> <http://www.allaboutjake.com/network/linksys/wlanexpert/>
>
> You can use signal strength to aim the antenna. *The response time on
> most wireless manager graphs aren't really fast enough to do it
> properly, but with patience, it can be done. *The problem is that the
> wide variations in signal strength you're observing is for real.
> 2.4GHz bounces around quite a bit. *You're seeing cancelations and
> reinforcements of multiple paths between endpoints. *Just pointing the
> antenna in some random direction, and walking around nearby, will
> yield substantial variations. *In an uncontrolled environment, this is
> what you'll get. *If you had an RF anechoic chamber, it will be far
> more stable.
>
> Just to make life difficult, you'll find that the RF output of a Wi-Fi
> xmitter various somewhat between 1Mbits/sec 802.11b thru 54Mbits/sec
> 802.11g. *Additional modes will also have different power levels. *You
> might want to lock your xmit mode to some favorite speed before the
> variations drive you nuts.
>
> Interference definately shows up in "link quality". *The problem is
> that chipsets have different ways to measure link quality. *Some use
> the noise level between transmission to calculate SNR (signal to noise
> ratio). *Others use the bit error rate to estimate the SNR. *I think
> there are at least two other methods in use. *All of them will show
> the effects of interference.
>
> For testing antenna, you need a (drum roll) antenna test range, a
> signal source, and a reference antenna with a known gain. *It doesn't
> have to be fancy, but it should make an effort to avoid interference
> and reflections. *I have a convenient WISP system located on a
> mountain top approximately 5 miles away. *I'm on a hill side,
> surrounded by trees. *The trees block most reflections and sources of
> interference. *The valley in between prevents ground bounce from
> becoming a problem. *I can point a directional antenna at the WISP
> system, and get a fairly stable signal. *Even so, I like to plot the
> signal levels with a data logger PC, throw out the extremes, and use
> the average values. *I always use the reference antenna to remove the
> effects of calibration, drift, and coax cables.

I *enormously* respect Jeff's views and this is not intended
to contradict them.

One approach that I have used successfully to
engineer a few wireless networks is to test the
link with fping.exe.

http://www.kwakkelflap.com/fping.html

This allows you to sent pings at the fastest rate possible
(i.e. send the next one as soon as you have a reply to
the last one) and provides a sensitive indicator of
good communications. It is best in my view to specify
long (say 1400 byte) packets. I cannot at the moment
recall the exact parameters that I like but post back
if you require further assistance with it.