Two frequency reed decoder and selective signalling device

Abstract

Abstract A SELECTIVE SIGNALLING SYSTEM USES TWO SEQUENTIALLY TRANSMITTED CALLING SIGNALS TO ACTUATE A RECEIVER AT THE REMOTE STTION TO CONDITION IT TO RECEIVE A MESSAGE. A DECODER IN THE RECEIVER INCLUDES TWO NETWORKS, EACH CONTAINING A FREQUENCY-SELECTIVE ELEMENT RESPONSIVE TO ONE OF THE CALLING SIGNAL FREQUENCIES. THE TWO NETWORKS ARE INTERCONNECTED IN SUCH A MANNER AS TO MINIMIZE "FALSING" DUE TO NOISE SIMULATING THE CALLING FREQUENCIES. THE FIRST AND SECOND NETWORKS ARE INTERLOCKED SO THAT THE SECOND NETWORK IS OPERATIVE TO RECEIVE A CALLING SIGNAL FOR A LIMITED TIME PERIOD AFTER TERMINATION OF THE PROPER FIRST CALLING SIGNAL. THE SECOND NETWORK IS POSITIVELY DISABLED BY A BIASING NETWORK WHICH MAINTAINS A TRANSISTOR SWITCH IN THE SECOND NETWORK IN A NONCONDUCTING STATE. THE APPEARANCE OF THE FIRST SIGNAL DISABLE S THE BIASING NETWORK WITHOUT ENABLING THE SECOND NETWORK. UPON TERMINATION OF THE FIRST CALLING SIGNAL, THE SECOND NETWORK IS CONDITIONED TO RECEIVE THE SECOND CALLING SIGNAL, AND THE BIASING NETWORK REMAINS INOPERATIVE OR DISABLED FOR A FIXED TIME-DELAY INTERVAL AFTER THE END OF THE FIRST CALLING SIGNAL. IF THE CALLING SIGNAL OF THE SECOND FREQUENCY IS RECEIVED DURING THIS TIME INTERVAL, THE SECOND NETWORK PRODUCES A CONTROL VOLTAGE WHICH ACTUATES THE RECEIVER AND CONDITIONS IT TO RECEIVE THE MESSAGE BEING TRANSMITTED TO IT. THUS, THE DECODER IS CHARACTERIZED BY THE FACT THAT THE SECOND NETWORK IS POSITIVELY DISABLED AT ALL TIMES EXCEPT THE FIXED TIME INTERVAL AFTER THE APPEARANCE AND TERMINATION OF THE CALLING SIGNAL OF THE FIRST FREQUENCY. THIS INSURES THAT THE DECODER IS VERY RELIABLE AND NOT SUSCEPTIBLE TO FALSING DUE TO THE APPEARANCE OF A NOISE BURST OR THE LIKE SIMULATING THE SECOND CALLING SIGNAL.

Inventors

• 👤 William G Mustain

Bibliographic Details