Tester and method for checking meter encoders in automatic meter reading systems

Claim 1

In an automatic meter reading system of the type having a meter including gear train driven dials and including a readable encoder, for generating a serialized message consisting of dial readings, driven by said gear train whereby each gear in the gear train has a definite mechanical relationship to the other gears in the train, a method of determining the meter dial readings and checking for encoder generated errors by interdial checking the mechanical angular position between the respective dial drive gears of the gear train comprising the steps of: (a) storing in a first addressable memory information representative of encoder dial readings; (b) storing in a second memory information representative of ranges of angular positions of gears driving said dials; (c) reading said encoder message; (d) utilizing, as an address for said first and second memories, a first dial reading in said message to effect the retrieval from said first and second memories, respectively, a numerical value proportional to said first dial reading and information representative of the angular position of the gear driving said first dial; (e) storing the angular position information retrieved from said second memory; (f) utilizing, as an address for said first and second memories, a second dial reading in said message to effect the retrieval from said first and second memories respectively of a second numerical value proportional to said second dial reading and information representative of the angular position of the gear driving said second dial; (g) storing the last angular position information retrieved from said memory; (h) comparing the angular position information first retrieved from said second memory with the second numerical value retrieved from said first memory; and (i) deriving an indication of an encoder interdial check failure when there is a non comparison.