| 摘要 |
A meter reader is disclosed for automatically reading utility meters at a telephone subscriber station and transmitting the meter data read to a central office over non-dedicated telephone lines in response to a call initiated by the central office. The meter reader is located at the subscriber station and includes, a microprocessor, a telephone isolating device, a call answering device, a ring detector, an off-hook detector, a ring generator, a data transmitter-receiver device and a modem. Each day the telephone is isolated from the telephone lines for a predetermined data access time. Any call made to the subscriber station during the data access time is answered by the meter reader. A coded signal is sent out over the telephone lines by the meter reader for the purpose of determining the source of the call. If the call is from the central office a coded reply signal is sent back and, the meter reader transmits the data to the central office. If the coded reply signal is not returned, the meter reader generates ringing signals for activating the bell in the subscriber's telephone. If the subscriber telephone is picked up at any time during the data access time, it is immediately unisolated from the telephone line.
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