Dean Sauer wrote:
*Power Utility Meters*
Specifically Sensus Meters in the 901-941Mhz MS & CN band
These are "smart meters" and report back power usage, and in certain
cases contain remote disconnect systems to disconnect..
There has been huge issues with the local city power company using these,
and several cases of the remote connects causing catastrophic fires.
These are being replaced.
Along with distrust in their accuracy.. hence why I have, another
monitor, see below.
I've been monitoring my own power usage this way for a little while. I
have been using this:
http://www.rtl-sdr.com/rtlamr-rtl-sdr-receiver-900mhz-ism-smart-meters/
In my particular case, I was interested in seeing the demand over time,
so I wrote some software (all Linux) to go with it. Specifically, the
chain goes like this on my machine:
1. rtl_tcp: this streams the raw I+Q signals out via TCP. You can start
from there and do anything that's possible with an SDR receiver.
2. rtlamr: reads stream from rtl_tcp and decodes to text.
3. energymon: my own C++ application which reads the text from rtlamr,
throws away all data other than for my own meter, parses the data and
slings it into a local SQL database.
4. energy.php: an extremely simple PHP page whose sole function is to
pull data from the SQL database and reformat it as JSON.
5. energy.html: a d3.js based web page that does a little additional
computation (specifically, it calculates demand from the raw energy
values and timestamps) and renders it as a 2D autoscaled plot.
Note that all but the last step is without any GUI, and in fact, the GUI
is essentially remote via a web browser rather than on the machine itself.
As a disclaimer, I am an engineer involved in the design of metering
devices, but not with the specific manufacturer you mention. These
devices are generally highly accurate, but you can easily test this for
yourself, and I encourage you to do just that. One simple way to do
this doesn't even require a radio. Plug in and turn on a single 100W
incandescent light into an outlet for which you know the controlling
breaker and assure nothing else is using power on that breaker. Go
outside to the meter and turn off all breakers. Write down kWh (energy)
reading. Turn on only the single breaker controlling the single 100W
light and leave the house in that condition for precisely one hour. At
exactly that time, turn off the breaker again and note the kWh reading.
The reading should be exactly 0.1 kWh greater than the previous reading.
At that point the experiment is done and you can turn on all the
breakers again.
Generally speaking, one can use gnuradio-companion to graphically design
the actual radio portion. Once it's designed, it compiles to Python and
if one hasn't included graphical I/O into the design, the resulting
Python application does not use or need any GUI.
Alternatively, there are many available gnuradio blocks from others that
can be used as-is or modified for your own particular purposes. Here
again, once you have a block, or a whole subsystem, you can easily
compile it into a CLI-based Python program, that that opens up a whole
other world of exploration for those of us who prefer CLI.
Ed
