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[aprssig] WIDEn-N works well in Denver.

Robert Bruninga bruninga at usna.edu
Thu Dec 23 19:38:44 UTC 2004

Concerning "WIDEn-N works well" in Denver:

> it appears that we must have one of the best APRS 
>environments in the country.  I  Lee's... UI-ALOHA add-on.  
>shows my ALOHA circle to be 320 miles.  That
>covers ALL of Colorado and parts of KS, OK, TX, NM,
> AZ, UT, WY, SD, and NE.

Then something is terribly wrong with that software or
something...  Looking at FINDU.com  shows more than 
100 APRS stations (not counting CWwx) within 46 miles 
of your station and ALL within view of only one digi.  
It is impossbile for your network to be working reliably 
if all of those  stations are on the air and using more 
than 1 digi hop. (and everyone that I checked is running 
4 hops or so!)

>There are many holes in the coverage ..., but the WIDEs
> we have here,...on the Front Range of the Rockies, are great.
>The 60 stations that UI-ALOHA used in its calculations included 
>about 10 stations with the farthest station being 515 miles away 

What about the other 90 ?

>We do get QRM from stations outside the area...
>The second program I ran was APRSNetSpy, by  N0KKZ, 
>which analyzes and counts packets heard in the area. 
>It... was seeing only 15 to 20 packets a minute, far below 
>the 60 that would choke an APRS network. 

Wow, Counts per minute are absolutely meaningless in
APRS in analyzing network overload.  A 100% fully overloaded
channel will have 0 per minute.  W e must not allow
packets-per-minute to be used anywhere as an analysis
of network performcnce.  If one wants to count something 
"per minute" then you have to go to the DIGI sites
and count how long the SQUELCH is open per minute

>With the APRS environment such as it is here in Denver,
>Colorado I don't see a need for "Firewalling" around the cities. 
> Maybe some day in the future, but WIDEn-N seems to be 
>working just fine.

Wow, from these simple comments, I see exactly the
opposite conclusion.  It appears to me that the network
in the Denver is suffering severe overload and reliability
for a low power tracker or urgent message must be nearly
impossible except for the strongest stations that can step
on everyone else.

To support just those 100 users in just the 46 mile radius of that
one digi, you should be getting over 1 packet per second!
The fact that you can only count 15 to 20 per minute
means that the other 60% to 75% of all packets transmittted
locally are being jammed and lost due to collisions.

Yes, you may "see" lots of stations on your map from 
over a million square miles in KS, OK, TX, NM, AZ, UT,
 WY, SD, and NE. and you might be "hearing" lots
of good packets, but what you are not seeing is all
that you are missing due to a completely overloaded
and saturated net into which locals with low power
find it impossible to use.

The success of APRS is not the number of stations
heard, but the reliability of a local  user being heard.

I'd be interested in looking into this situtation closer
to see what is really going on in Denver and whether an
HT or low-power tracker can be used.  It sounds to
me like it would be impossible due to total abuse of
WIDEn-N and high digis.

Again, I couild be all wrong.  I am kibitzing from afar,
but the data I see and the data you presented seem
to be widely divergent....

thanks.  Lets see what we can do about this.


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