[NLRS] RF read water meters

[Dr. Gerald N. Johnson]

Mine is an Orion made by Badger Meter Company. The battery operated 
readout only updates when I push the read button.

Many water meters have some sort of rotating wheel or chamber that could 
spin a little generator through some gears to charge a nicad or nimh or 
lihium ion battery or super capacitor to accumulate power for 
responding. Just causes some pressure drop and on this rural water 
system, there's a pressure regulator on the main side of each customer 
meter because its miles to the nearest water tower and there are hills 
and valleys, causing the line pressure to vary and to be as high as 200 
psi which domestic plumbing can't stand. My pressure runs about 55 psi 
by my indoor gauge that I use to check for leaks by shutting off the 
main and watching for any pressure drop. And if I detect a low pressure 
while the main is on and nothing is using water here, I call the water 
company to report a leak. So far they've already known about it but 
thanked me for the call.

The previous readout was on the post with an LCD. Water service came to 
this house in 2004 and that readout was beyond reading with very low 
contrast a couple years ago so it lasted only about 6 years. The meter 
from the same water company at my farm put in about 1994 uses a veeder 
root type display. It never moved, though I used considerable water 
spraying crops some years, one day they checked, and compared the remote 
readout to the meter, replaced the remote readout and sent me a bill for 
2000 gallons of water. Since then I've rented out the farm and the 
tenant can't get to the hydrant and has a cheaper source of water for 
spraying and while the remote probably has broken again, the dials on 
the meter itself haven't moved either because I've probably used ten 
gallons a year since then occasionally washing my hands when working on 
equipment there.

I could get the remote readout on this Orion system next to a wide range 
scope and counter and see what its putting out. Might not last long 
enough for the counter. If its under 450 MHz, I'll be able to see it 
with my scope.

As for data and modulation format, there are many that can do the job, 
the amount of data is small, probably includes a meter number as well as 
the reading and at least a meter number in the query from the remote so 
as to be usable in crowded urban applications with a dozen or gross of 
meters per 200 feet of street. I suppose it could even be encrypted with 
forward error correction and still use up less than 64 bits per 
transmission.

73, Jerry, K0CQ

On 7/20/2012 1:43 PM, Doug Reed wrote:
>
>
> They replaced my meter last month in Maplewood. I haven't bothered to
> try and find what frequency it operates on. The meter they installed
> here works from scavenged power, most likely from the water flow winding
> a spring until it trips to drive a magnet and generate a voltage spike
> in a coil. At least that is the way I'd probably build it. I don't
> really like the spring option because it might break, but how many
> mechanical watches ever broke a main spring?.... Whatever it is has to
> be designed for more than 20(?) year MTBF or the water company isn't
> going to want it.
>
> I'd tend to go for a simple burst transmission with an ID code and a 16
> or 24-bit pulse count for the water usage. The TX would be random based
> on water usage and if any packet was missed, the next would have the
> most current data.
>
> ITI/GES used to build battery powered alarm sensors using AM pulse
> position burst transmissions at 320MHz, about 10-20mw RF output. The
> cheap receivers were designed to hear a minimum 2mw transmitter at
> 500-600 feet LOS. The best receivers we sold would hear the TX at
> 2100-2500 feet, or about 1/2 mile. This technology was 20 years old and
> would have been easy to integrate into a water meter. These days the new
> products are using ASIC chips with the RF and other electronics
> integrated on a single chip. Lower parts count should improve
> reliability.... I would choose to use 434MHz or another low-power band
> rather than 915MHz if I could help it.
>
> I wouldn't expect the meter to have an active RX-TX system as I've heard
> suggested because that would require a more reliable power source that
> I've described. But if your water meter mounts outside, it might have
> solar cells. If it has an AC power connection indoors, then it might
> have a RX-TX polling or mesh system. On the other hand, maybe the water
> wheel generator has more power capability than I'd expect. It should
> certainly be capable of more "work." Of course this is all pure
> speculation on my part, although I was involved in a similar
> demonstration project 20 years ago....
>
> 73, Doug Reed, N0NAS.
>