Voice switching control system

A voice switching control system for controlling voice signals for transmission between stations, each station including a microphone and a loudspeaker, comprising:

• (a) at least two voice switches disposed in different voice signal transmission channels, respectively;
• (b) each of said transmission channels being operatively connected between the microphone of one of the stations and the loudspeakers of the other stations;
• (c) means for sensing each output voice signal of the microphones of the stations and each input voice signal to the loudspeakers of the stations;
• (d) comparators each for comparing a signal representing the sensed output from the microphone of one of the stations with a signal representing the sensed input to the loudspeaker of the same station;
• (e) each one of the comparators selectively producing either a first signal or a second signal in accordance with the relative amplitudes of the output voice signal of the associated microphone and the input voice signal of the associated loudspeaker;
• (f) logic circuits each for controlling the associated voice switch at a selected one of two positions, a first position defining an ON state of the voice switch and a second position defining an OFF state of the voice switch;
• (g) each one of the logic circuits having a first control input for receiving the output of the associated comparator and a second control input for receiving the output of the other comparators;
• and
• (h) each one of the logic circuits being placed in a set state so as to control the associated voice switch so as to be in its first position upon the receipt, by the first control input, of the first signal from the associated comparator and the receipt, by the second control input, of the second signal from any one of the other comparators, each one of the logic circuits being placed in a reset state so as to control the associated voice switch so as to be in its second position upon the receipt, by the first control input, of the second signal from the associated comparator and the receipt, by the second control input, of the first signal from any one of the other comparators, each one of the logic circuits having its plate changed so as to control the associated voice switch so as to change the position thereof upon the receipt, by the first control input, of the first signal from the associated comparator and the receipt, by the second control input, of the first signal from any one of the other comparators, whereby a voice message newly inserted into a microphone of any one of the stations serves to interrupt another voice message which has been transmitted to the loudspeaker associated with the microphone, and the newly inserted message is transmitted to any other station without attenuation of the voice signal introduced by the associated voice signal switch.