[NLRS] RF read water meters

Sat Jul 21 10:34:32 EDT 2012

Thanks everyone for the responses.

It sounds like there is nothing to worry about w.r.t. the new meter.

73, 
Jim Klassen (KB0UAZ)

On Jul 20, 2012, at 2:42 PM, Dr. Gerald N. Johnson wrote:

> 
> 
> 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.
>> 
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James Klassen
Graduate Student
University of Minnesota
Natural Resources Science and Management
210 Green Hall
1530 Cleveland Avenue N.
St. Paul, MN, 55108
Email: klas0037 at umn.edu