[aprssig] Repeater 'telemetry'

[Bill Herrmann]

At 08:16 PM 9/6/2020, Michael Pittaro wrote:
>  I think it might be a good idea to monitor telemetry over packet or APRS.

APRS is an ideal tool for this.

>What sort of hardware / software combinations are typically used for 
>this type of setup? Mostly, I'm interested in environmentals and 
>things like battery status / charge status, and possibly repeater activity.

A club I used to be involved in (I moved away) used to use telemetry 
for a solar powered site they shared with a couple government 
installations. We actually notified them of a problem with the solar 
power system prior to it becoming a problem. The site had telemetry 
for a long, long time, but it looks like they've had to move to a new 
site and that site doesn't seem to be using it in the same way.

I believe that they were using a KPC-3+ TNC with 2 channels of 
telemetry. They had battery voltage and solar voltage as I recall. 
Since the TNC sent the APRS info we could use FindU (or any APRS 
client supporting telemetry) to check the trend data over time, which 
is how we spotted the charging problem. Over time you get a pretty 
good idea of what it should look like.

FindU has some good information available at 
http://www.findu.com/cgi.html#tele-list
Note the link to "Full details on APRS Telemetry"

You can get a list of stations currently sending telemetry with 
http://www.findu.com/cgi-bin/tele-list.cgi and that will also get you 
links to the two telemetry displays.

How well they display depends on whether each station is sending the 
APRS telemetry equations that tell how to interpret the data. Also, 
by default you'll often see several channels of data flat-lined as 
most stations aren't sending "all" of the APRS telemetry channels. 
(There are 5 analogs and 8 binary channels in the APRS spec.)

It looks like the club I used to be involved with is just sending a 
voltage (guessing battery) in the text portion of a message now. 
That's not very useful IMHO. Do the APRS telemetry and do it right.

Note aprs.fi also supports telemetry. I'm just more familiar with 
telemetry on FindU.

Last, but not least, you may also want to consider sending weather 
data. APRS supports both telemetry and weather data. (Equipment 
temperature or building temperature probably fit best in telemetry.)

Hope that helps!
Bill KD7MJC