Abstract: A bi-directional, digital data transmission system is disclosed for transmitting an interrogation signal in a first direction from an interrogation unit to a data gathering transponder unit, and a data return signal in a second direction from the meter or data gathering transponder unit to the interrogation unit. This system comprises a single transformer having a primary winding coupled to the interrogation unit and a secondary winding coupled to the transponder unit. The interrogation unit generates an interrogation signal comprised of a first train of regularly occurring digital clock pulses and transmission interval pulses, each transmission interval pulse defining a transmission interval for the transmission of the data return signal. The transmission interval is set to be of a sufficient length to permit the transformer to desaturate to a level to permit efficient transmission of the data return signal to the interrogation unit.

Abstract: A utility data gathering system is disclosed as comprising a register including a series of index members coupled to a meter mechanism. Each index member includes a plurality of contacts and a switch arm moveable with its index member. The meter mechanism is responsive to utility consumption for moving the index members to positions indicative of the utility consumed, whereby each switch arm completes in normal operation a circuit with just one of its plurality of contacts dependent upon the position of its index member. A digital computer is programmed for performing first and second scans of each contact of each index member to obtain corresponding first and second sets of data indicative of a completed circuit through the switch arm and contacts of each index member. The completed circuit data obtained from each of the first and second scans are compared and if the circuit data of the first and second scans are different, an alarm manifestation is generated.