The Cent-A-Meter has an AC current sensor you clip over the mains wire coming in to your house, (there's a version with three sensors for three phase power). The sensor transmits data on 433.92MHz to a receiver in the house that displays how much power your house is using.
Obviously I'd like to log the readings and display a graph of usage over a day and week. It's a well constructed device internally:
The main circuit board is clearly laid out and labelled:
I like the RF board with its spring antenna on the right. Clearly labelled is a pad where you can pick up the serial data.
My hope was that the protocol would be somehow simple, perhaps a pulse that varies proportionally with the current detected - I understand some monitoring systems use the flashing LED on modern electronic power meters which flashes like this. Unfortunately for me it looks to be more sophisticated than that and the actual data packet is surprisingly long for just sending one reading.
Anyhow this is a good start. It looks like there are receivers that can receive these signals so I might leave the standard client in tact and get an additional receiver to try amateur protocol analysis on.