[aprssig] Open Source/Commercial Use acceptable APRS Alternative?

Scott Miller scott at opentrac.org
Mon Aug 7 22:37:53 EDT 2023

It might have been used in Australia but the protocol development was 
done by me here in California, back when I was active on SAR myself. The 
basic idea was a simple type-length-value format with efficient binary 
encoding, no weird math required (Mic-E uses exponents that were easy 
for Bob in GWBASIC but were a pain for embedded developers), 
extensibility, and graceful handling of unsupported features.

One of my favorite aspects of it (which I totally cribbed from 
MIL-STD-2525B) was the object type/symbol system. Bob's scheme was very 
ad hoc and symbol types got added as he saw fit with no particular 
system. It was fine in the early 90s when there weren't a lot of station 
types but it got unwieldy. The OpenTRAC scheme is hierarchical and makes 
it easy to add fine-grained distinctions between station types while 
letting clients not up to date on the latest still figure out roughly 
what it is - like you can tell something is a ground vehicle even if you 
don't know that the rest of the code specifies a class A RV. The 
protocol finds use in some of my totally unrelated projects - if you go 
to a Cirque du Soleil show where a performer has several LED hula hoops 
on stage and sniff WiFi traffic you might see OpenTRAC packets over UDP 
advertising a station type of for ground 

One thing I really wanted to do back then was to allow efficient 
real-time and non-real-time traffic handling for SAR situations where 
teams and vehicles were moving in and out of contact with each other and 
with network infrastructure, so the latest information would propagate 
through the network even if portions were isolated for hours. A vehicle 
passing over a ridge might pick up a field team's transmissions, and 
then move back into network coverage later and pass those updates on. 
Another thing I wanted to do that would be a lot more feasible now was 
to support RFID-based tracking of vehicle contents, including 
passengers, so the command post would know that Rescue-3 had a 400 foot 
rope bag and a Stokes litter, for example. People and equipment have a 
way of getting shuffle around in the field such that the command post 
loses track of who and what is where.

Cheap, ubiquitous satellite data coverage is coming so maybe none of 
this will matter. I've made it part of the informal mission statement of 
the radio side of my company, though, that we're here to develop 
solutions that don't /require/ constant connectivity. Silicon Valley 
likes to operate on an assumption of reliable data coverage, to the 
extent that I can't even reliably listen to my downloaded music on my 
favorite music app because when you move out of coverage the app simply 
hangs for 10 minutes or more. Yeah, it'll play offline, it just doesn't 
gracefully handle /going/ offline and no one cares to test it.

Man, I haven't ranted on the SIG in ages. Feels like the old days.


On 8/7/2023 6:48 PM, wa7skg wrote:
> IIRC, OpenTRAC was something going on in Australia. There was an 
> offshoot SARTrac used for Search and Rescue operations that is still 
> used in some areas. There are a few SAR teams around here that use 
> SARTrac on both amateur and public safety frequencies (not the 
> standard APRS channels) to keep track of search teams and put them up 
> on big screens at the search base.
> Michael WA7SKG
> Stephen H Smith via aprssig wrote on 8/7/23 9:58 AM:
>> On 8/7/2023 8:33 AM, Greg Troxel wrote:
>>> John Gorkos<jgorkos at gmail.com> writes:
>>>> In the deep corners of my brain, I recall there was an alternate
>>>> protocol written Once Upon A Time that supported location
>>>> tracking/telemetry/messaging over AX.25, but was NOT APRS and not
>>>> limited to non-commercial use.  Does anyone have the name and/or links
>>>> to something like that?  I'm working with a non-profit for event asset
>>>> tracking, and I don't want to cross any lines.  We're using LoRa for
>>>> short- to mid-range vehicle/personnel tracking and I'd rather not
>>>> reinvent wheels.
>> You may be thinking of Scott Miller N1VG's  (of Argent Data and 
>> OpenTracker fame)   OpenTRAC   protocol. It was proposed as an 
>> alternative to the increasingly kludged APRS protocol.  It was 
>> intensively discussed on this list in the 2003-2004 time frame, but 
>> apparently went nowhere.   It's website still exists at:
>> <http://opentrac.org/>
>> but there appears to have been no activity for nearly 20 years.     A 
>> standards document IS on the web site that you might find useful as a 
>> starting point for your project.
> _______________________________________________
> aprssig mailing list
> aprssig at lists.tapr.org
> http://lists.tapr.org/mailman/listinfo/aprssig_lists.tapr.org
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.tapr.org/pipermail/aprssig_lists.tapr.org/attachments/20230807/7da60adc/attachment.html>

More information about the aprssig mailing list