[aprssig] Airborne Digis

[Tom Hayward]

On Mon, Sep 14, 2009 at 11:07 AM, Gregory A. Carter
<gcarter at openaprs.net> wrote:
> Hi Tom,
>
> The only problem with this issue is that at 2000-4000 feet now you're
> digi-ing ALL WIDE1-1 stations within earshot not just my trackers.  The
> first direct issue here is now there is a possibility in overloading the
> airborne digi in which case it will be too busy to digi my priority
> packets.  The second issue would be now I'm taking WIDE1-1 requests from
> adjacent valleys and duplicating their packets even further when paired up
> with any other fill-in digi's that are actually in their area on the ground.

I understand this issue, and I think it's worth testing.

It is common to install a permanent digipeater at 4000+ feet that
digipeats ALL WIDE1-1 stations AND ALL WIDE2-1 and WIDE2-2 packets. It
seems to me that a digipeater flying at 2000 feet would cause no more
"interference" than this permanent digipeater.

Tying up your special digipeater is an interesting problem... My hunch
is that most of the packets with a WIDE1-1 path during a search will
be coming from your trackers. The APRS area I'm familiar with is the
Puget Sound basin in western Washington. Here we have a lot of APRS
activity, but generally only a handful of active mobile stations at
any time. If your area is similarly active, I don't see digipeating
these few mobile's packets being detrimental to tracking of your SAR
teams.

I wouldn't worry about duplicating packets digipeated by other fill-in
digis. Every digipeater, including your airborne digipeater should be
digipeating immediately, so all the fill-ins should be transmitting
simultaneously. The FM capture effect takes care of the rest. No
additional airtime required.

Tom KD7LXL