Welcome to APRS Telemetry Watcher


APRS Telemetry Watcher (APRS-TW) is not another APRS tracking client. Rather, it's purpose is to watch for APRS telemetry traffic and make the operator aware of conditions reflected in the telemetry data. The layout and functionality of the program is the exclusive property of Charles "Chuck" Bland. It is free to use and enjoy. You just don't get to say it is yours or sell it to anyone.

APRS-TW gets APRS channel data from an APRS soundcard packet engine. It works with AGW-PE, UZ7HO, and DireWolf soundcard packages. It is up to the user to install and setup these packages. But never fear, it isn't that tough of a proposition, and there is an excellent site for helping you get started.

I would appreciate hearing from users. There is nothing like releasing a program to the world that causes those bugs that couldn't be found in testing to come out of the program. I would also be interested in hearing your suggestions for functionality. To that end, join the APRS-TW Yahoo Group.

Telemetry Parameters


In order to display telemetry information with the proper precision, descriptions, and units, additional information needs to be provided. This information can be learned from over the air transmissions or can be provided in advance in the Cache file.

Chatper 13 of the APRS spec goes into great detail of the PARM, EQNS, UNIT, and BITS messages that supply this info and how it is used, so I won't go into it here. APRS-TW does use these messages. But if you add your own, you can tell APRS-TW, on a per unit basis, to ignore these messages and just use your values.

You can go to APRS.FI and look-up the telemetry on a given unit (if it is heard by an iGate) and find the telemetry parameters if you haven't heard them over the air. For a unit you own, finding these values isn't always easy. So, I think it is a good idea to start collecting these values as people start using them with their particular hardware. I have started a spreadsheet and am providing a PDF copy. Feel free to use it. But even more important, as you find working values for specific units, post that info on the Yahoo Group so that the document can be updated. I don't know of any place where this information is together in one spot.

KISS Monitor Program


As I am working on adding a KISS interface to APRS-TW, I wrote a KISS monitor program as I was figuring out the serial interface and KISS formatting.

You can download the program here. It is pretty straight foward, breaking down the details of each packet.

How APRS-TW Got Started


For several years, the Amador County Amateur Radio Club (K6ARC) has been supporting two bicycle events with communications. Our typical setup has our net operations in the same area with the event directors, and our radio operators riding with the SAG vehicles. This type of operation helps us allocate these resources and is a great contribution to the success of the overall event.

If you have supported one of these types of events before the advent of APRS, you probably know that the most frequent communication you will hear on your radio channel is the net controller asking someone "where are you?" It wasted a lot of channel time.

This year, we were able to do something about it.

This was the first year we deployed our eight MT-AIO Trackers from Byonics and two digipeaters to provide the needed coverage over the mountainous terrain of the courses. We monitored the movement of the SAG vehicles using UI-View and maps where we had highlighted the various courses. The trackers and the digipeaters were also sending their battery voltage and air temperature measurements via APRS telemetry, but that information had to be monitored by staring at the raw APRS data screen periodically in hopes of seeing an update scroll by. It was not an effective way to watch for battery and temp issues with any of the hardware.

This information is important, since our digipeaters and trackers are all battery powered. It is important to keep an eye on the battery voltage so we can know ahead of time when battery changes are needed. Our digipeaters are also temporarily deployed in outdoor locations, typically in the sunshine. Keeping an eye on the temperature of the equipment allows us to make sure we will not have any heat failures.

The event coordinators absolutely loved what we could do for them, but I felt we could do some things better to make sure our hardware resources were all operating properly. As a result, the difficulty of keeping an eye on the telemetry inspired me to write APRS Telemetry Watcher.