[aprssig] Generators and LPG Conversion (was APRS in NOLA)

Richard Hoskin vk3jfk at amsat.org
Sat Sep 3 09:03:19 CDT 2005

> -----Original Message-----
> From: aprssig-bounces at lists.tapr.org [mailto:aprssig-
> bounces at lists.tapr.org] On Behalf Of VE7GDH
> Sent: Saturday, 3 September 2005 5:00 AM
> To: aprssig at lists.tapr.org
> Subject: RE: [aprssig] Generators and LPG Conversion (was APRS in NOLA)
> Using a TNC that draws very little current would be a good idea. A nice
> addition would be the ability to drop the output power on the radio if the
> voltage dropped below a certain point, or even shut it down temporarily so
> the battery would have a chance to charge if the voltage was too low to
> operate the radio.

We have designed a device that does just that.
It was designed for a solar digipeater site we had.

The device called SiteAlert monitors Battery Voltage, Temperature and
Traffic count. It transmits these values every 30 minutes as APRS telemetry
which can be graphed on findu. 

SiteAlert has 2 contact sensing inputs and a low-voltage cut-out. We use one
input for mains power failure detection, the other for a site entrance alarm
but you can use the inputs for whatever like.

When an input is tripped or a voltage threshold reached SiteAlert will send
you an APRS message and display a warning Icon on your APRS map. We have set
up our units to send an APRS message to the APRS Email server to notify us
via email of any alarms. The email system is also connected to the mobile
phone SMS system which means we can choose to have an SMS alarm as well.

The system works very well, I have it installed on 4 digipeater sites so
far. It's allowed me to notify the site owner of problems at his site, I can
see how well the batteries at a site are holding up and how much traffic
load is on the digi amongst other things. 

You can get more information on SiteAlert at


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