[aprssig] Hybrid APRS

Fredric Moses fred at moses.bz
Sat May 28 06:04:14 CDT 2016


I guess we have for awhile now here for some of our events we support with communications.  On the BikeMS events we support ( 3 weekends per year in Michigan ) we have two hybrid setups.

The first goes in the normal sag/med units.  I consists of a Mobile Motorola DMR radio for voice and a VHF radio for APRS.  We use argentdata’s ot3’s with garmin nuvi 350’s.  They are in a two radio hump style mount that we bungie cord to the floor in the rental trucks and vans..  http://imgur.com/7NIdCvR <http://imgur.com/7NIdCvR>  We have the OT3’s setup for smart beaconing.  They also get a GPRS/GSM based TK103 type tracker unit that has a combo external gps/gsm antenna.  A prepaid h20 wireless sim card provides the cell link. $10 bucks gets you 90days of tracking.  The TK103 sends 30 second updates to our https://www.traccar.org/ <https://www.traccar.org/> server.  We have written an aprs parser for the server and it has a table of device id’s to aprs callsigns.  It publishes those updates to our arpsc server.  All of our iGates are also connected to that same aprsc server.  All posits are time stamped as well so if there is a delay kinda deal the clients figure it out.     So these units can send/rx messages via the nuvi and see other stations around them via the same nuvi as well.  Objects also show up. (Rest stops / incidents)  But they also transmit a higher posit rate via cellular to aprs-is only.

The second hybrid units are in the radio/ncs car, tech truck and main med unit.   They consists of a VHF data radio with a bluetooth interface for the TNC. A tablet running aprsis32 ( our primary aprs client ) lte cradlepoint router with diveristy external antennas which provide wifi in the van/truck. also a mini usb gps provides streaming nema.   With the TNC via bluetooth and the internet connection via WiFi the only cable running to the tablets is power and it can be popped off if needed for moving around or about.   This lets us have the VHF data as RXed off air of the smart beacon feed as well as the aprs-is feed of that same data plus the 30 second posits feed.  We connect our aprsis32 clients to the same aprsc server the igates/traccar server use.

Were the routes are for these events cell coverage goes in and out. So having the hybrid setup works well. We built aprs coverage for all the events so we know that data will get through and provide basic location updates.  And when in cell range we get high frequency posit updates..  Same callsign is used on both so what ever packet hits the client wins kinda deal.

This has worked well for us the past few years but this will be the last year for the TK103 style units as ATT is sunsetting the 2G/GPRS network at the end of the year.  I have started to work on a 3G/LTE based hardware tracker now.  I picked up an electron 3g board from particle.io <http://particle.io/> and have it sending GPS posits to particle’s api…    I also ordered some of those pocketchip computers.. https://getchip.com/pages/chip <https://getchip.com/pages/chip>   Pop a USB 3g/lte stick on it. and gps module see how it goes.. they both have pluses/minuses…  Cost is a big deal… I paid 30 bucks for the TK103’s and 15 bucks for the combo gps/gsm antennas.  So if i can keep the new 3g/lte units under 150 per that is my goal.

Having higher posit rates is very useful for other events we do.. Marathons/Runs.  Especially lead or mid pack units.  Tail units move slow enough a new posit ever 2 minutes is fine.

So that is how we here in Michigan at least "hybrid APRS"

--
Fredric Moses - W8FSM - WQOG498
fred at moses.bz

> On May 28, 2016, at 05:23, Andrew Rich via aprssig <aprssig at tapr.org> wrote:
> 
> Is anybody doing hybrid APRS
> 
> Radio and cellular
> 
> -----------------------------
> Sent from my iPhone
> Andrew Rich
> vk4tec at tech-software.net
> www.tech-software.net
> 0419 738 223
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> aprssig at tapr.org
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