Carrier current intercommunication system utilizing dual action squelch means

Claim 1

IN AN INTERCOMMUNICATION SYSTEM INCLUDING A PLURALITY OF STATIONS AND A POWER LINE INTERCONNECTING SUCH STATIONS, MEANS IN EACH STATION FOR PREVENTING NOISE WHICH APPEARS ON THE POWER LINE FROM BEING RECEIVED AND REPRODUCED IN THE RECEIVER PORTIONS OF SAID STATIONS, COMPRISING: A SIGNAL CHANNEL INCLUDING A DETECTOR CIRCUIT CONNECTED WITH THE POWER LINE AND HAVING A NEGATIVE TERMINAL; AN AMPLIFIER TUBE IN SAID SIGNAL CHANNEL HAVING A SCREEN GRID AND AN ANODE; AN INTEGRATOR CIRCUIT INCLUDING A RESISTOR AND A CAPACITOR, CONNECTED WITH THE NEGATIVE TERMINAL OF SAID DETECTOR CIRCUIT; A SOURCE OF POSITIVE POTENTIAL; A CONTROL TUBE HAVING A CONTROL GRID CONNECTED WITH THE CAPACITOR OF SAID INTEGRATOR CIRCUIT, A SCREEN GRID CONNECTED WITH SAID SOURCE OF POSITIVE POTENTIAL, AN ANODE CONNECTED WITH SAID SOURCE OF POSITIVE POTENTIAL THROUGH A HIGH RESISTANCE, AND A CATHODE CONNECTED TO SAID SOURCE OF POSITIVE POTENTIAL THROUGH A VARIABLE RESISTANCE; A HIGH RESISTANCE CONNECTING THE ANODE OF SAID CONTROL TUBE TO THE SCREEN GRID OF SAID AMPLIFIER TUBE; AND A SECOND HIGH RESISTANCE CONNECTING THE ANODE OF SAID CONTROL TUBE TO THE ANODE OF SAID AMPLIFIER TUBE, WHEREBY WITH NO SIGNAL BEING RECEIVED, SAID CONTROL TUBE CONDUCTS HEAVILY AND PROVIDES A LOW VOLTAGE TO THE ANODE AND SCREEN GRID OF SAID AMPLIFIER DISABLING SAID AMPLIFIER, AND WITH A SIGNAL BEING RECEIVED, A NEGATIVE VOLTAGE IS APPLIED TO THE CONTROL GRID OF SAID CONTROL TUBE AND THE CONTROL TUBE IS CUT OFF, SAID LONG TIME CONSTANT CIRCUIT ACTING TO PREVENT BURSTS OF HIGH AMPLITUDE NOISE FROM CUTTING OFF SAID CONTROL TUBE.