[NLRS] RF read water meters

[Doug Reed]

I'm slightly surprised by the internal battery since that will require 
them to perform a service call very 10 years. But that is built into the 
estimated lifetime cost of the new meter.... Once every 10 years to 
replace a battery has to be cheaper than 4 times a year to read the 
meter.....

I would bet there is a PLL based transmitter in the box and the 
operating frequency is based on a programmed multiplier off the CPU 
crystal. That is pretty common these days. The CPU crystals are not very 
accurate but usually end up being a bit better than SAW-based transmitters.

I would expect when they say hopping they mean each transmission is on a 
different one of those three frequencies and the data collection site 
would simply have three receivers on one antenna. This would improve the 
chances of a transmission being heard in a crowded metro environment or 
apartment scenario. Although I'm surprised they don't have some sort of 
random timing between transmissions, either based on usage or TX serial 
number, or a combination.

Ten years ago ITI/GES built an alarm sensor with a rated 10 year battery 
life using a 3.6V 2Amp-hour AA-size lithium battery. The only reason it 
was rated at 10 year battery life is because the battery manufacturer 
wouldn't warranty the batteries for 20 years. We based its battery life 
on having under 10ua standby current. New designs 3 years ago had 
standby current under 1ua. Chip technology had improved a lot...

But I have to say a 4 second update rate is very high and will reduce 
battery life considerably. I don't understand why they want that fast an 
update rate instead of just using a longer counter in the meter. I could 
see having data that fast if they want to graph your water usage every 
second of the day, but that really makes little sense. But maybe they 
have a sliding scale and slow down the TX rate if there is no change in 
the reading?.... But if you have a fixed rate it is easier to know when 
there is a problem....

If you want some major power for long term low current usage, take a 
look at the size DD lithium batteries from SAFT. I think they were 
14Amp-hours in a double-D size package. They were sounding pretty good 
for an Antarctic data collection project except they were only rated to 
-40 degrees Centigrade rather than -60 C..... :-)

73, Doug Reed, N0NAS.

Dr. Gerald N. Johnson wrote:
>
>
> Found more searching for Badger Orion. One tech reference says:
>> WIRELESS ORION RF TRANSMITTER
>> The ORION transmitter operates in the 902-928 MHz frequency
>> band at 916.45 MHz, which requires no FCC licensing. The
>> transmitter sends a fixed value RF signal to the serialized receiver
>> approximately every 4 seconds. The transmitter is powered
>> using an internal lithium battery and is encapsulated to ensure