Reading AMR RF signal... possible? - RF Cafe Forums

 Post subject: Reading AMR RF signal... possible?

Posted: Thu May 20, 2010 1:12 pm 

Hello. I found this forum via Google.

First, let me preface that I know litterally next to nothing about RF. I am by no means an engineer. I'm not even a related hobyist. I'm a guy that wants to do something specific and I want to know if you people (that know a lot more about RF) think this is possible, and perhaps help me gauge what might be required.

In many homes these days, we have RF water meters commonly associated with the acronym "AMR" or Automatic Water Metering (wikipedia entry). The gist of it is that the meter has an RF antennae and broadcasts some data (presumably the serial number and meter reading) at some interval. The utility company can then drive around and read the meter without getting out and without having to gain access to the home.

I want to be able to read that meter too. I can get on my hands and knees and manually look at it with a flashlight, but it is very inconvenient. In an attempt to reduce my water usage (we live in a semi-desert) I would like to view the data on my computer. I can develop the rudimentary software to make use of the data for my purposes.... I just don't have any clue how to read the meter electronically (wirelessly).

I searched in hopes that there were generic readers out there, hopefully with a PC interface, but I found very little. These have been around a long while, but it seems not too many people have any desire to read them. I did find one chinese website that lists "water meter reader module" but that's it. I've contacted them a couple of weeks ago, but no response.

Any thoughts?

- Steven

 Post subject: Re: Reading AMR RF signal... possible?

Posted: Sat May 22, 2010 2:19 pm 

How remarkably helpful.

 Post subject: Re: Reading AMR RF signal... possible?

Posted: Sat May 22, 2010 9:09 pm 

Greetings s_mack:

I sent a note to an AMR expert I know to address your question, but he's on vacation through Monday.

My personal experience, having worked on an AMR system back in the early 1990s (Enscan/Itron, in the 900MHz ISM band), is that the RF transponders on the meters only respond to a properly encoded interrogation signal, and then respond with an encrypted consumption message. A 3rd-party reading system would have to be privy to the encryption key, which was unlikely at the time. Maybe things have changed since then, but I doubt it.

_________________
- Kirt Blattenberger
RF Cafe Progenitor & Webmaster

 Post subject: Re: Reading AMR RF signal... possible?

Posted: Sun May 23, 2010 2:50 am 

Thanks for your reply.

I have since learned a couple of things.

First, while the system does use a pseudo-spread spectrum signal, it is not at all for encryption but rather for reliability. The algorithm is in fact published by the patent holder and is used across various brands which are interoperable.

Second, there are some systems that require a wake-up signal but it seems most modern ones (including this one) does not. It broadcasts every 14 seconds whether or not anyone is listening.

There's supposedly an Opensource (ish) project in the works, but if you go to their site right now (www.openamr.org) you'll see its down at least for the moment so who knows where that's at.

I'd still like to do something, however in my research since posting I now know I can't do what I'd like to do, even if I could establish communication. I was hoping for a practically real-time setup so that, for example, I could flush my toilet and see on my computer some 14 seconds later that the toilet flushed (based on expected volume). Unfortunately it can't work like that. While it does broadcast every 14 seconds, it updates WHAT is broadcasts only once every hour.

So it can't be as useful as I'd hoped, no matter what. But I'd still like to get somewhere on this.

- Steven

 Post subject: Re: Reading AMR RF signal... possible?

Posted: Tue May 25, 2010 12:20 pm 

Kirt, were correct in your response. Everything is encoded, encrypted and secure these days. It's going to be pretty darned difficult for someone to read that meter if it has state of the art software in it. Even if one were to go to the trouble of de-spreading, demodulating, etc, the signal and collecting the bits, chances are, they may be encrypted in some fashion.

Most utilities (and your government) want these smart meters, whatever they measure, to be highly secure.

Then there is how the meter is read. Is it a drive by poll-respond system? If so, pinging the meter by a customer would limit the battery life of the meter which may not be desired by the utility.

There are movements afoot, which promise what the poster wants. Google and others are applying that to electric.

http://www.google.com/powermeter/about/

Perhaps the poster may want to call his utility that is utilizing the AMR system and ask if they can set up a web page with his readings on it for him? Many of our customers provide that service, I don't know if his utility has such a program, but it doesn't hurt to ask.

I hope that the replies are helpful.

 Post subject: Re: Reading AMR RF signal... possible?

Posted: Tue May 25, 2010 12:37 pm 

I think you're presuming too much. Perhaps a bit paranoid?

There's no reason to "protect" meter readings. Its just a serial number and the current reading - entirely non-sensitive data. There's no privacy issue whatsoever, so the only reason would be to ensure that company X's reader can't ready company Y's meter. And that doesn't seem to be the case, because most readers assure they can read all meters using the same frequency standard, which it appears most do.

Plus, if they wanted to protect it so bad then why would they publish the algorithm?