Remote meter reading method and apparatus

For use in a meter reading system using a telephone line for communication of meter data, a transponder comprising;

• detecting means for detecting a control signal on the telephone line,
• a microprocessor including a read/write memory,
• a meter pulse generating means coupled with said meter for producing an electrical meter pulse corresponding to a predetermined meter event,
• first coupling means for coupling the meter pulse generating means to the microprocessor, said first coupling means comprises a multiplexer circuit and a reset circuit each having an input coupled with the meter pulse generating means, the reset circuit having an output coupled to a reset input of the microprocessor for switching the microprocessor from a quiescent mode to an active mode in response to said meter pulse and for switching it to the quiescent mode after the occurrence of said meter pulse,
• a tamper detector coupled with an input of said multiplexer for applying a logic signal thereto in response to tampering with a circuit of said transponder,
• means for switching the microprocessor from the quiescent mode to the active mode in response to said meter pulse,
• a data signal generator coupled with the microprocessor,
• said microprocessor having means for interrogating said multiplexer when in an active mode to increment a pulse count register in the read/write memory and to set a tamper flag in said read/write memory,
• second coupling means for coupling said detecting means to said microprocessor, and
• means for switching the microprocessor from the quiescent to the active mode in response to said control signal, said microprocessor being programmed to cause said data signal generator to transmit encoded data representing the pulse count and said tamper flag stored in the read/write memory in response to a command signal and for switching the microprocessor to the quiescent mode after the encoded data signal is transmitted.