[amsat-bb] Re: S band interference solution

John Champa k8ocl at hotmail.com
Thu Oct 5 10:12:11 PDT 2006


OK, you're right.  Some folks can't handle ridicule, so I will try to be 
more tutorial and less shaming. But it never stops amazing me how folks in a 
technical wireless avocation such Amateur Radio can have such an extremely 
narrow focus in wireless!

For example, hand a standard satellite telephone to the average Ham, even an 
AMSAT member, and ask him to make one phone call, just one.  Or give them a 
Linksys 802.11g Access Point (AP) from Radio Shack and ask them to set up a 
small wireless local area network (WLAN).  Or this one: Hand them a old 
laptop PC and ask them to upgrade it to a WiFi wireless client and then go 
down to their local coffee shop and surf the Internet.

Please keep in mind, these are ALL common consumer wireless devices! And our 
lovely test subjects are all supposedly sophisticated wireless licensed 
RADIO amateurs.  But chances are excellent they would NOT HAVE A CLUE how to 
do any of these common consumer wireless tasks.  They left their wireless 
curiosity on the door step somewhere and got super specialized.   
Opps...there is that ridicule tone again.  Got to stop that!  (HI)

Why am I rambling on like this?  Because the result of all this is that 
satellite Hams can send a signal on a 50k mile round trip to some bird they 
helped design (remotely) and build (remotely) themselves, but they can NOT 
figure out how to manage a $60 unlicensed wireless device their neighbor 
bought at Best Buy.  So they spend hours on this reflector lamenting the 
potential loss of a cherished Mode S instead applying just a tiny little bit 
of traditional Amateur Radio ingenuity and tracking down and dealing with 
the low power device(s) in their own neighborhood.

However, there is one saving grace.  The WiFi users are no better, buth then 
they don't claim to some kind of wireless guru.  They will come to me 
because their AP is running slow.  They suspect interference.  I will tell 
them about free NetStumbler software.  Load it and tell me what you see.

Next day.  They return and say they saw that all three of the other 
neighbors and themselves are all on the device's default radio channel 6!  
So I advise them to go back into their AP configuration software and change 
their AP channel to 11.  The next day...miracle!  The slow problem went 
away!  Amazing!

Well, Hams can do the same thing!  Chances are if they use NetStumbler to 
look at their neighborhood they will see the following frequency channel 
distribution of devices:

90%  on channel 6 (most common WiFi default channel) --   NO problem.  
Ignore these.
5%   on channel 11 -- NO problem, that's not even in the Ham Band.  Ignore 
10% on channel 1  --  Ahh!  Those are the problem!  They must be gently 
persuaded to go to some channel above 1.  That may solve your problem.  
Better yet, ask them to move to some channel above 6.  That way they are 
starting to get out of the Ham band entirely.

That 10% on channel 1 may amount to only 1 or 2 WiFi users in your entire 
neighborhood.  A little TVI-type PR in reverse and a little TLC and the 
problem is solved!

How's that Luc?  A little more encouraging?

Vy 73,
John - K8OCL
AMSAT Life Member 1069

>From: Luc Leblanc VE2DWE <lucleblanc6 at videotron.ca>
>To: AMSAT-BB at amsat.org
>Subject: [amsat-bb] Re: S band interference solution
>Date: Thu, 05 Oct 2006 10:08:49 -0400
>On 5 Oct 2006 at 8:21, John Champa wrote:
> > I really do get bored reading about all these threats to Mode S from 
> > etc.
> >
> >
> > For a bunch of supposedly sophisticated wireless guys, you sure don't 
> > beans about
> > consumer grade wireless devices.  That includes our wonderfully 
> > but pessimistic AMSAT satellite engineers!
>I agree... but it sometimes very hard to convince and ridicule may prove 
>too much for some readers
>but it can be of some help for some stubborn minds who are not pessimistic 
>but unrealistic.
>The medium is the message...The content is the audience...;)
>Luc Leblanc VE2DWE
>WAC basic,CW,Phone,Satellite
>Skype VE2DWE
>Sent via AMSAT-BB at amsat.org. Opinions expressed are those of the author.
>Not an AMSAT-NA member? Join now to support the amateur satellite program!
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