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Well, nothing says we have to stay at 1200 baud. There have been 9600 baud amateur radio modems around for over a decade. And a parallel protocol (using a different AX.25 PID value) could be used for acknowledged messaging and log transmission (perhaps metering
the log transmissions to prevent clogging the channel) while asynchronous un-acked APRS is still used for position and status reporting.
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<div>Can we go to a wider (more spectrum - eating) channel to gain baud rate? In the quoted system, there might not be voice repeaters to piggyback off, so we don't have to be constrained by their limitations. </div>
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<div>I don't think we want to get as complex as the current cellphone network technologies; aside from the cost and patent issues, those networks are all about centralized control and 1-hop access to that central control (which presumably wouldn't be available
in the SAR environment, or they'd just use cellphones).</div>
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<div>Just my $.02.</div>
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<div>Andrew, KA2DDO</div>
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-------- Original message --------<br>
From: SARTrack Admin <info@sartrack.co.nz> <br>
Date:09/05/2014 02:43 (GMT-05:00) <br>
To: TAPR APRS Mailing List <aprssig@tapr.org>, sarcomm@yahoogroups.com, Search_and_Rescue_Communications@yahoogroups.com
<br>
Cc: <br>
Subject: [aprssig] Digital two-way Radio communication in emergency situations <br>
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<div class="PlainText">Hi all,<br>
<br>
As the CEO of SARTrack Limited, and developer of the SARTrack Search and <br>
Rescue software, I get occasionly approached by Emergency Services <br>
organisations who basically require a full two-way *radio* based <br>
tracking and communication system for teams in the field, in disaster <br>
situations where all other communication networks have failed or are out <br>
of range.<br>
<br>
SARTrack Limited did build type-approved (non Amateur Radio) based APRS <br>
Trackers and Digipeaters, but we no longer do this.<br>
While the SARTrack software can transmit Operation Logs and Objects over <br>
an APRS radio link, this is really not recommended, as the 1200 bps <br>
radio channel is simply not fast enough for that kind of work, and APRS <br>
is obviously not the right protocol for reliable two-way communication.<br>
<br>
My question is this:<br>
- What does currently exists in the area of affordable two-way, medium <br>
speed, digital radio equipment, which can be somehow connected to a user <br>
interface like maybe a smartphone or another device which enables <br>
display on a screen and entering data on a (digital) keyboard?<br>
<br>
I start to wonder if it would be possible to develop a 'commercial' <br>
package which would make it possible to send people out in the field, on <br>
foot or vehicle, carrying a VHF radio based system like this, and using <br>
(portable) Digipeaters for same system to setup links to a remote base. <br>
There is clearly a market for this, as 'hi-speed' satellite based <br>
systems are incredible expensive and probably more in the militairy <br>
domain...<br>
<br>
The radio link speed would have to be at least 9600 bps, and it should <br>
preferably a full digital signal like PSK or QPSK or some other suitable <br>
digital modulation type.<br>
<br>
Any ideas and information welcome.<br>
<br>
Thanks<br>
<br>
Bart Kindt<br>
SARTrack Limited<br>
<a href="http://www.sartrack.co.nz/">http://www.sartrack.co.nz/</a><br>
-- <br>
<br>
SARTrack Developer and CEO<br>
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