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Cellular network data transmission system

  • US 5,146,486 A
  • Filed: 08/31/1989
  • Issued: 09/08/1992
  • Est. Priority Date: 08/31/1989
  • Status: Expired due to Term
First Claim
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1. A system for transmitting data between a subscriber site and at least one monitoring station, comprising:

  • sensor circuitry for generating data responsive to an event at the subscriber site;

    first transmission circuitry responsive to said sensor circuitry operable to transmit the data from the subscriber site using a cellular telecommunication network and including a cellular transceiver that transmits to and receives from said cellular telecommunications network radio frequency signals, a digital communicator connected to said sensor circuitry for receiving data therefrom, and a cellular interface connected to said digital communicator;

    second transmission circuitry directly connected to said digital communicator and being operable to transmit the data from the subscriber site using a landline telecommunications network;

    fault detect circuitry including a first lead line connected to said digital communicator and a sensor lead line connected to said cellular interface for continuously monitoring the operability of the system and the integrity of said cellular telecommunication network, said fault detect circuitry including circuitry operable to detect a loss of a radio frequency data link transmitted by said cellular telecommunications network and to generate a lost radio frequency link signal responsive to a loss of the radio frequency link;

    circuitry coupled to said fault detect circuitry for receiving said lost radio frequency link signal and transmitting data to the monitoring station using said landline based telecommunication network responsive to said lost radio frequency link signal received from said fault detect circuitry indicating a lack of integrity in said cellular telecommunication network.

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