[NLRS] RF read water meters

[Chris Elmquist]

If these are fairly modern radios, there's a good chance they're built
from various vendors "sub GHz" devices.  TI, Freescale, ATMEL and many
others offer integrated microprocessor+radio on a single die that are
very popular in this space.

If that's the case, the radio is likely to be a GFSK, 2GFSK kind of
thing with +10 to +15 dBm transmit power and -100 to -120 dBm typical
receive sensitivity.  It might run with somewhere between 600 and 1200
bps data rates and it may frequency hop too.

It could very well be a mesh network design where the radio at your house
can be a repeater for others nearby, just as others could be repeaters for
you depending on signal qualities, topology and lots of other stuff--
basically, the network is very dynamic.

I encounter lots of this stuff on both 900 and 2.4 GHz these days
and there is high demand for these technologies in wireless metering,
sensing and other products.

The high level of integration you get with the processor and the radio
on one die drives the cost way down and that makes them popular-- not to
mention the unlicensed part 15 status.

Chris N0JCF

On Friday (07/20/2012 at 10:58AM -0500), Dr. Gerald N. Johnson wrote:
> 
> 
> Its likely in 902 -928 our shared band with part 15 devices because then 
> they need no license. The range is short and the amount of data is 
> small, so power is low and bandwidth smaller. When the display on the 
> post quit, the rural water association here put in a remote readable 
> device, and their newsletter hints they may go to a mobile meter reader 
> instead of customers reading the meter. I know for several months after 
> they installed the new meter and reader, that I detected truck tracks in 
> the gravel driveway a couple times a month as they apparently checked to 
> see if it was really reading right. I'm using less than 10% of the water 
> the previous home owner did each month. Low flow faucets do work.
> 
> If I run low on projects I could fire up a general coverage receiver or 
> scanner and see if I can identify the reader and meter transmissions and 
> their characteristics. I expect a 300 baud FSK signal based on the time 
> delay for a 7 digit display.
> 
> 73, Jerry, K0CQ
> 
> On 7/20/2012 10:43 AM, plefever at cpinternet.com wrote:
> >
> >
> > Jim,
> >
> > I live in Burnsville and they came through a few years ago
> > and retrofitted all the meters in the city with RF read
> > modules.
> >
> > I was home the day the tech came to install the module. They
> > sure love it when you move the water softener and clean and
> > vacuum the area around the meter and provide a work light
> > for them! I had the same question for the tech and I asked
> > him what frequency the meter was on. He stated that I was
> > the 2nd person to ask that and he asked if I were a ham too.
> > At first he was hesitant to tell me but he saw the bench
> > with the scope and spectrum analyzer on it and he said he
> > thought I could probably figure it so he just told me the
> > exact number. I don't recall the frequency but like Gary's
> > it was in the 900 Mhz range.
> >
> > I don't think the module on the meter talks unless its
> > polled so I don't think you will hear anything from it. I
> > don't have anything on 900 Mhz personally so I have no
> > actual experience though.
> >
> > 73
> >
> > Phil, KB0NES
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-- 
Chris Elmquist