[amsat-bb] Re: Digi @ Dayton?

Bob Bruninga bruninga at usna.edu
Mon May 16 13:53:40 PDT 2011

> What you say does make sense - I didn't think about 
> the digi congesting the network since everyone would 
> be within simplex range.  My main concern is
> that I can get digipeated using the stock duck on the 
> TH-D7A that I will be using for backpack APRS.  If I 
> can't reach any digipeaters in the area, I need to go 
> to plan B for an antenna.

But why do you need to reach a digi?  You will be within wet-noodle range of every APRS person at Dayton and they can hear/see you even if you are on low power.  There will hopefully be an IGate at the Hamvention to pick up everyone.

Even if you run 50 watts, you aren’t going to get into a Dayton digi because any digiepater that can hear the area will be 100% jammed on the input.

Limiting everyone to simplex or 1 hop only is the same technique used in the Losangeles basin.  Everyone that is there is there, and the channel is full, so no reason to bring any more packets in or out.

See http://www.aprs.org/fixingLA.html

Ore more generically, everything there is to know about digipeating, and MINIMIZING channel load.


Good luck

-----Original Message-----
From: Bob Bruninga
Sent: Monday, May 16, 2011 10:24 AM
To: amsat-bb at amsat.org
Subject: [amsat-bb] Re: Digi @ Dayton?

> [does] anyone set up a digipeater at Dayton,
> or do we rely on the local digi’s?

Proper operation of an event like Dayton would suggest that putting up a
digipeater would be the worst thing to do.  With over 300+ mobiles and
portables beaconing away all in simplex range of each other, a digipeater
would do nothing but drastically reduce the reliability of the channel by
half or more.

The proper way to handle a ham radio event with a massive influx of APRS
operations is to:

1) Have no digi at the focal point (Hamvention)
2) Have all digis going out 30 miles in all directions be ONE-HOP DIGIS
ONLY.  That is, they only respond to WIDE1-1 or WIDE2-2 and nothing else.
They digipeat once and do callsign substitution so the packet goes no
3) Strategic IGates are placed right at Hamvention so they hear everything
in simplex range
4) Additional IGates are configured so that every surrounding digi going out
30 miles has an IGate to hear the one-hop packets.

5) Doing all the above, then the hundreds of APRS mobiles and portables do
not have to change anything.  They just drive into town with their normal
WIDE1-1,WIDE2-1 settings.


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