Master antenna line communication system

In combination with an antenna system having an antenna for receipt of a communication signal and a common antenna line connected between said antenna and a plurality of locations for common distribution of such communication signal to said plurality of locations;

• transmitting means for generating a querying information signal different from said communication signal directly connected into said antenna like for distribution of such information signal over said line to said plurality of locations;
• a plurality of sensors, each of which is connected to said antenna line at an associated one of said locations for receipt of said information signal and includes means responsive to receipt of said information signal by selectively generating and applying a reply information signal to said antenna line in response to a predetermined condition of the sensor circuitry;
• receiving means connected to said antenna line for generating an alarm signal in response to receipt within a selected time interval of a predetermined number of reply information signals from any one of said sensors;
• and means on said antenna line for preventing said information signal and any communication signal on said antenna line from interfering with one another;
• said transmitting means continually generating successive querying signals and distributing the same over said antenna line to said plurality of sensors, and said receiving means generating said alarm signal in response to receipt of a pair of reply signals spaced in time from one another an interval indicative of one of said sensors generating said reply signals in response to succeeding ones of said querying signals;
• each of said successive querying signals generated by said transmitting means being an electrical scan pulse having a predetermined time of initiation;
• each of said sensors including timing means adapted to apply a reply signal to said antenna line if said predetermined condition of said sensor circuitry exists at a predetermined time after receipt thereby of said scan pulse, which predetermined time is different for each of said sensors;
• said receiving means including means for distinguishing between reply pulses received from different ones of said sensors on the basis of the time at which said reply pulse is sent thereto after transmittal of an electrical scan pulse on said line;
• power supply regulating means for receiving electrical power on said antenna line and regulating the same to provide an essentially constant power level for operation of said sensor;
• and said timing means of each of said sensors including means providing a time constant for setting said time at which said sensor generates said reply signal after receiving said scan pulse signal, means for generating said reply signal after said predetermined time, and means responsive to the passage of said predetermined time as determined by said time constant means by causing said generating means to initiate said reply signal.