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

John Gorkos jgorkos at gmail.com
Mon Aug 7 20:46:26 EDT 2023

I was more concerned with copy write and patent violations than with 
frequency issues.

The use case is pretty straight-forward:  we have a very large event 
that takes place over ~3500 acres of desert.  It's perfectly flat, and 
about 80,000 people show up for it.  The organization that runs it uses 
a Kenwood trunking system for voice comms among the thousands of people, 
paid and volunteer, that keep things on the rails.  There are also 
hundreds of utility vehicles, ranging from golf-carts to heavy diesel 
fuel trucks.  A non-trivial amount of radio chatter on the 25 or so talk 
groups is "where are you"? Usually, that query is from a 
command-and-control center (i.e. fuel truck dispatch) to a mobile unit.

The majority of the non-working participants are bicycle mobile, and 
unfortunately, there is a lot of bicycle re- and mis-appropriation.  
Being able to track my $1000+ electric bicycle in the case where it 
wanders off is worth taking an extra few hundred dollars worth of gear 
out there.

In both cases a super-cheap, short- to mid-range tracking solution would 
be great.  In fact, this is almost exactly the kind of environment (in 
my mind) that Bob had when he started promoting a tactical, data-driven 
position aware radio network.  But, in this case, it's just too big for 
amateur radio.  I suppose if we started using 440, multiple 2m channels, 
etc, and started playing fast and loose with licenses, if could be done, 
but the beauty of it is that it doesn't have to be done.  The LoRa 
transmitter chips are perfect for this use case.  They put out about 
20dbm, they come with really nice microcontrollers that have no problem 
polling a GPS serial stream, assembling a packet, and deciding when to 
transmit it.   Plus, we get to use everything from 902-928MHz.  Also, 
being in the middle of the desert, there's not a lot of interference.

I'm initially using ~40 byte on-air messages at 125kHz for an on-air 
time of ~300ms.   One of the goals this year is to experiment with the 
range of modulation speeds,spreading factors, and  coding rates that 
LoRa offers to see what gives me the best range/on-air rates.  The 
absolute maximum distance you can possibly need to transmit is 3 miles.  
And like I mentioned earlier, it's REALLY flat.  There are two bits of 
kit I'll have out there:  trackers and iGates.  Trackers are Heltec 
HTCC-AB02S GPS/LoRa dev boards with a 600mAh battery that's good for 6-8 
hours, and can be powered/recharged via USB.  You can get them on Amazon 
for $25 or so.  iGates are Lilygo T-Beams.  They have the GPS, LoRa, and 
throw in an ESP32 for WiFi/Bluetooth connectivity, and run about $40.  
The Organization provides a point-to-multipoint Ubiqiti network that 
covers the event space, so there are pockets of WiFi coverage scattered 
across the whole service area.  Igates are deployed into these Wifi 
enclaves to get the data from RF to backhaul as quickly as possible.  
There are no digipeaters; everything is one-and-done.

Once the data is on backhaul, ideally it would be processed and used 
onsite.  That requires a level of access I don't have, so everything 
gets sent out of the event.  First hop is 60gb/s AirFiber, then it's 
dropped onto actual fiber into the Internet. And that's where the real 
line-crossing happens.  Right now, all of the data is in APRS format.  
Some of the call signs are tactical, some of them are actual ham 
callsigns with -[A..Z] SSIDs.  The iGate firmware on the T-Beams has the 
ability to connect directly to APRS-IS.  It also provides an MQTT 
client. There are plenty of great online and standalone APRS-aware 
clients (YACC, Xastir, and of course, APRS.FI come to mind).  There's 
already quite a bit of LoRa APRS traffic on APRS-IS.  Most of it is 
ham-originated, but I'm pretty sure it's not ALL that way.  For me 
making sure some naked hippie doesn't ride off on my bike at Burning 
Man, using APRS-IS is fine.  For a large organization tracking hundreds 
of assets, absolutely not.

Which brings me all the way back to my original question.  Is the APRS 
protocol appropriate for a network like this?  How much of the APRS 
infrastructure can/should I leverage to a) use it for personal use (i.e. 
where's my bike) and b) for proof-of-concept to the host Organization to 
see if we want to expand to dozens or hundreds of trackers in the 
future?  Should I invest time in OpenTRAC and something like Traccar, or 
perhaps just set up a standalone aprsc node (or several, for redundancy) 
and run everything as a walled-garden?  There's no profit in it for me, 
or for anyone, really, save for the equipment manufacturers.  It's more 
of a "I've been playing with IoT, and digital radio, and vehicle 
tracking, and tactical situational awareness both personally and 
professionally for over 30 years, and this is the first time I've really 
seen a 'perfect storm' of need, opportunity and availability of cheap 
hardware really collide."

Open to thoughts, especially from those of you that have been to the playa.

On 8/7/23 11:29, John Langner WB2OSZ wrote:
> I haven't seen anything that would prohibit the use of the APRS protocol for
> commercial use.
> The issue would be using the Amateur Radio frequencies.
> What, exactly, is the use case?
> Would hams be present for the event?
> We've put APRS trackers on vehicles in town parades so everyone can track
> their progress.
> You mentioned that LoRa is already being used.
> QEX July/August 2023 describes an implementation of APRS for the LoRa TTGO.
> https://github.com/lora-aprs
> 73,
> John WB2OSZ
> _______________________________________________
> aprssig mailing list
> aprssig at lists.tapr.org
> http://lists.tapr.org/mailman/listinfo/aprssig_lists.tapr.org
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