Importance

Loading Importance Indicators...

Abstract

A telephone dial-inbound data acquisition system with demand reading capability. The system has particular application for remotely reading utility meters. A remote data unit (RDU) dials up a host computer on a periodic basis. The RDU is assigned a callback start time by the host computer. The RDU calculates an actual callback time based on the callback start time and a randomly generated time delay. The RDU dials up the host computer via a modem when the local time, as shown by an on-board real-time clock at the RDU, equals the calculated actual callback time. Meter reading data is then transferred to the host computer. The RDU also contains circuitry for detecting a polling signal generated by the host computer. Upon detection of this polling signal, the RDU immediately dials back the host computer and transfers utility meter reading data to the host computer. The RDU will also immediately dial back the host computer if an alarm condition occurs, e.g. tampering or a low battery condition. The RDU contains circuitry for characterizing the on-hook and off-hook electrical characteristics of the telephone line to ensure that the RDU does not interfere with normal operation of a customer's telephone line.

Loading the Abstract Image...

First Claim