[aprssig] High speed modems? (500 mi demo)

Robert Bruninga bruninga at usna.edu
Mon Jul 18 08:08:36 CDT 2016

Just last saturday, we demonstrated 9600 baud links over 500 miles from
North Carolina to NY (6 links) as part of the annual Appalachian Trail
Golden Packet event.  All the links worked at 9600 just as well as at 1200
baud.  Although it was only a few hour test, we do want to make the link
permanent using level 4 packet nodes.

9600 baud doesnt do much for APRS as the individual packet overheat and TXD
delay only provides about a factor of 2.  But for file transfer, of bulk
data the speed really pays off.  Since 9600 baud is built into every
Kenwood APRS radio its time to do something with it...



On Mon, Jul 18, 2016 at 4:04 AM, SARTrack Admin via aprssig <
aprssig at tapr.org> wrote:

> This is a bit off topic, but I have been asked (and not for the first
> time) if there is a way to do emergency communications on VHF/UHF at
> reasonably medium to higher speed.
> My SARTrack software can do some of the work via APRS, but due to the
> connectionless state, it is not very suitable for reliabe transfer of
> critical data, and it is way to slow.
> I have users who are now looking at DMR for data transfers (because they
> already use commercial DMR radios for Voice and GPS location data) but
> these radios are by default very narrow-band, and are aiming more towards
> the 6.26 kc bandwidth than to 25 kb bandwidth, let alone more.
> What we really need is a fully digital VHF or UHF radio modem, which
> enables us to do make one-to-one connections, and possibly some kind of
> one-to-many data transfers.
> Looking at the TAPR website, most of the things I find there are very
> old.  I would like to find some kind of system which uses the latest
> technologies to get the most data over a bandwidth which can still be used
> in VHF/UHF.
> If there is a mailing list more suitable for this topic, please let me
> know.
> Thanks,
> Bart ZL4FOX
> http://www.sartrack.nz/
> --
> Bart Kindt
> SARTrack Developer and CEO
> _______________________________________________
> aprssig mailing list
> aprssig at tapr.org
> http://www.tapr.org/mailman/listinfo/aprssig
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