[aprssig] Argent Tracker4

Scott Miller scott at opentrac.org
Tue Mar 13 18:31:38 EDT 2018

I swore I was going to name my next tracker something more creative, but 
I'm better at programming than marketing, and I think the Tracker4 name 
is going to stick...

In any case, it's close to being ready for production.  It's been on the 
back burner for a while with the ADS-SR2 repeater taking up so much 
development time but the T3 has been unavailable for a while since we 
ran out of enclosures and the T4 is far enough along that I'm moving it 
up rather than ordering more parts for the aging T3.

The most obvious change with the T4 is WiFi support.  It still has USB 
and the command shell has been improved, but the easiest way to 
configure it is with a web browser.  It has a responsive web interface 
that works well on a desktop, tablet, or smart phone. It'll also act as 
a standalone IGate, and the shell is accessible via telnet.

Instead of the T3's primitive scripting system, it has a complete BASIC 
interpreter with some APRS-specific functions to make it easy to 
automate actions.  This part's still under development, but it's already 
a whole lot more flexible and easier to use than the T3's scripting.

It'll still support Dallas 1-wire for sensors, but it adds Modbus RTU 
over RS-485.  1-wire has never done well for long cable runs and doesn't 
tolerate noise very well, but RS-485 is reliable over thousands of feet 
and in noisy environments.  Modbus RTU has been around for decades and 
is supported by all sorts of sensors and I/O devices.  I've been testing 
with everything from < $10 quad relay boards from China to $400 
intrinsically safe industrial I/O modules and assorted temperature, 
pressure, and humidity sensors.  The BASIC interpreter has access to 
Modbus and does floating point math so transforming sensor data is easy.

I'm planning to add the ability to upload weather data to Weather 
Underground directly, but that's not done yet.  It'll also have a basic 
weather display in the web interface.

It has only one external RS-232 port versus two on the T3, but it adds 
an internal GPS receiver with SMA antenna connector and includes a GPS 
antenna so most users won't need to connect any serial devices.  It has 
32 MB of internal flash memory that can be used for local data logging, 
and a battery-backed real-time clock that can be automatically synced to 
the GPS time and/or NTP.

Physically it's about 1/4" larger than the OT3m in all dimensions, with 
a flanged aluminum case that's easier to mount to a surface. I expect 
we'll have more compact versions to replace the T3-Mini and T3-Micro 
eventually but those are going to have to wait until late in the year.

I'm waiting on another round of PCBs right now that will test out a 
different connector layout and if those work out they should be in 
production in a few weeks.  The introductory price is planned for around 

I opted not to use Bluetooth because frankly Bluetooth has been a huge 
pain in other projects I've done, it's locked down on iOS, and when 
everything is working right it gets you the equivalent of a dumb serial 
connection.  The T4 supports WiFi Direct and can be used without other 
network infrastructure or while your phone is connected to another WiFi 
network (at least for most current phones), and while iOS doesn't 
support Direct (of course) it'll at least connect in legacy mode.

I'll make sure that one way or another APRSdroid is able to connect over 
the WiFi link, and for desktop apps it'll support AGWPE's TCP API.

The software has a high degree of commonality with the ADS-SR2 repeater 
and has some non-APRS related features that will probably stick around, 
like the ability to play WAV files over the radio port and send and 
receive DTMF tones, both of which are handy for scripting.  All of the 
SR2 software features that don't require two radio ports, including 
Echolink connectivity, *could* be implemented on the T4's hardware but 
I'm not going to promise all of those at the same price.  If there's 
sufficient interest I might make some extra features available as paid 
add-ons, so you don't have to pay for features you don't need and so I 
can keep paying the rent.

If there's anything you'd particularly like to see in the first release, 
let me know!

Thanks and 73,


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