December 27, 2019

Tracking down a Water Leak with RTLAMR

Earlier in the year Clayton discovered that his water bill had suddenly gone up one month. Suspecting a leaky appliance he set out to discover what it was by using an RTL-SDR and the rtlamr decoder. The rtlamr decoder is able to decode water meters that transmit usage data wirelessly via the Itron ERT protocol which is typically found in the unlicensed 900 - 920 MHz band in the USA and Canada.

Clayton wrote a simple Python script to plot the usage data extracted by rtlamr, and after a week determined that water was being consumed at 10 liters an hour even while away from home. Suspecting a leak in the toilets he turned off their valves and the next day saw that the reading remained constant when away, indicating that he'd found the leak.

A water leak graphed by decoding an Itron ERT water meter with RTL-SDR

February 13, 2014

RTLAMR: An RTL-SDR Receiver for 900MHz ISM Smart Meters

Smart meters are meters that monitor electricity usage and wirelessly transmit consumption data to the electricity company. They are a part of the “smart grid”, and allow for better electricity control and usage reporting.

Douglas recently wrote in to us to let us know about his work on RTLAMR, an RTL-SDR based Automatic Meter Reader (AMR) decoder. Currently Douglas has tested the decoder on his local Itron C1SR smart meters, but notes that it should work on any meter using the common AMR protocol known as Electronic Receiver Transmitter (ERT).

Over on his website Douglas has also done a neat writeup discussing the ERT protocol and showing how he decoded it, including the steps of preamble detection, matched filtering, bit slicing and error correction.

We would like to note that we also recently posted about a similar project about decoding Elster R2S smart meters.