Electronic time-division-multiplexed PABX telephone system

A communication system for audio information comprising:

• a system clock, a transmission cable having a looped timing line and a looped communication line separate from said timing line and running parallel thereto, each of said lines having an outgoing leg connected to said system clock and outgoing therefrom and a return leg returning from the outer end of said cable to said system clock, a timing signal generator in said system clock for generating timing signals applied to said outgoing leg of said timing line and which timing signals divide time into repetitive frames of time slots used to divide the usage of said communicataion line into a plurality of time-division-multiplexed communication channels, said communication channels including one assigned exclusively to signalling and supervision use and a plurality of audio communication channels assigned exclusively to audio communication use, a plurality of appliques each having a communication receive terminal connected to said outgoing leg of said communication line and a communication receive terminal connected to said return leg of said communication line, each of said appliques also having a send timing terminal connected to said outgoing leg of said timing line and a receive timing terminal connected to said return leg of said timing line, means in each applique for producing status signals representing the current status of the applique, means timed by timing signals extracted from said outgoing leg of said timing line through said send timing terminal for injecting said status signals from each applique through said communication send terminal onto said outgoing leg of said communication line in said signalling and supervision channel thereof, means in each applique timed by timing signals extracted through said receive timing terminal thereof from said return leg of said timing line for extracting through said communication receive terminal thereof signals from said communication line which appear in said signalling and supervision channel, and said appliques further including means responsive to the status signals interexchanged by said appliques over said communication line in said signalling and supervision channel for making and breaking talking path connections between said appliques which talking path connections are made through said audio communication channels.

In an electronic time-division-multiplexed communication system for audio information, the combination comprising:

• a timing signal transmission line and an audio signal transmission line, separate from said timing signal line, running parallel to each other and each having a first end and a second end, means for dictating unidirectional signal flow along the length of each of said lines in the electrical direction away from its first end and toward its second end, a timing signal generator for injecting timing signals onto said timing signal line at said first end thereof for propagation therealong to said second end thereof, a plurality of appliques each having an audio send terminal and an audio receive terminal both connected to said audio signal line, each of said appliques further having a send timing terminal and a receive timing terminal both connected to said timing signal line with the aforesaid terminals being so arranged that the signal propagation time along said timing signal line from the send timing terminal of any one of said appliques to the receive timing terminal of any other of said appliques is equal to the signal propagation time along said audio signal line from the audio send terminal of said one applique to the audio receive terminal of said other applique, means in each applique for injecting audio signals onto said audio signal line at times referenced to timing signals received through its send timing terminal, and means in each applique for extracting audio signals from said audio signal line at times referenced to timing signals received through its receive timing terminal.

In an electronic time-division-multiplexed communication system, the combination comprising:

• a linear transmission medium arranged in the form of a loop having a bight at one end of said loop and having two parallel legs of equal length disposed adjacent to one another, a timing signal generator connected to one end of said linear transmission medium for injecting timing signals onto said transmission medium, one of said legs of said linear transmission medium comprising a sending portion beginning at said timing signal generator and extending outwardly therefrom to said bight and the other of said legs comprising a receiving portion beginning at said bight, a plurality of appliques connected to said transmission medium and each including a means for injecting communication signals onto said transmission medium and a means for extracting communication signals from said transmission medium, said communication signal injecting means of each applique including a communication send terminal and a timing send terminal connected to said send portion of said transmission medium and said communication signal extracting means of each applique including a communication receive terminal and a receive timing terminal connected to said receive portion of said transmission medium, said communication signal injecting means of each applique including means responsive to the timing signal obtained from said transmission medium through its send timing terminal for timing the injection of communication signals onto said transmission medium, and said communication signal extracting means of each applique including means responsive to the timing signal obtained through its receive timing terminal for timing the extraction of communication signals from said transmission medium, and means in said transmission medium dictating unidirectional flow of said timing signals and of said communication signals along the length of said sending portion of said transmission medium in the direction away from said timing signal generator and toward said bight and along the length of said receiving portion of said transmission medium in the direction away from said bight.

A communication system comprising:

• a lineal transmission medium including a communication line, means time dividing the usage of said communication line into a number of time-division-multiplexed communication channels over which information may be transmitted on said communication line, said communication channels including at least one signalling and supervision channel and a plurality of audio communication channels, a plurality of appliques located along said transmission medium, means providing each of said appliques both sending and receiving access to said signalling and supervision channel of said communication line, means providing each of said appliques sending access to one of said audio communication channels, means providing each of said appliques with receiving access to all of said communication channels, and means in each applique for conditioning said applique to accept signals from any of said audio communication channels, said conditioning means including a first enabling means controlled directly by said applique for selectively enabling said applique to receive information from any of said audio communication channels and a second enabling means controlled by signalling and supervision information transmitted to said applique by others of said appliques for also selectively enabling said applique to receive information from any of said audio communication channels, said first and second enabling means being in series with one another so that both of said first and second enabling means need to be enabled with respect to any given one of said audio communication channels to condition said applique to accept signals from said one audio communication channel and whereby the completion of a talking path from a sending applique to a receiving applique is controlled both by the sending applique and the receiving applique.

A communication system comprising:

• a lineal transmission medium including a communication line, means time dividing the usage of said communication line into a member of time-division multiplexed communication channels over which information may be transmitted on said communication line, said communication channels including at least one signalling and supervision channel and a plurality of audio communication channels, a plurality of appliques located along said transmission medium, means providing each of said appliques both sending and receiving access to said signalling and supervision channel of said communication line, means providing each of said appliques sending access to one of said audio communication channels, means providing each of said appliques with receiving access to all of said audio communication channels, a means for repetitively transmitting onto said signalling and supervision channel of said communication line a list of address words addressed to respective ones of said appliques, means in each applique responsive to the receipt of an address word addressed to it to inject onto said communication line immediately following such address word at least one other word indicating its current status, each address word and such at least one other word immediately following it forming a message, a memory means in each applique for receiving messages appearing on said communication line and for storing information received from said messages concerning the status of all other appliques, a plurality of audio communication sources each connected to a respective one of said appliques and each including a means for supplying control signals to its applique, and means in each applique responsive to the control signals supplied thereto by its audio communication source and by the information stored in its memory means for conditioning each applique to make and break talking path connections with others of said appliques

A communication system comprising:

• a lineal transmission medium including a communication line, means time dividing the usage of said communication line into a number of time-division-multiplexed communication channels over which information may be transmitted on said communication line said means time dividing the usage of said communication line including means for transmitting on said transmission medium and along with the information on said communication line a timing signals consisting of repetitive frames of pulses, which pulses divide each frame into a number of time slots, said communication channels including a plurality of audio communication channels, a plurality of appliques located along said transmission medium, means providing each of said appliques sending access to one of said audio communication channels, means providing each of said appliques with receiving access to all of said audio communication channels, each of said appliques having a send terminal connected to said communication line at one point along said transmission medium for said sending access and a receive terminal connected to said communication line at a second point along said transmission medium for said receiving access, a first counter in each applique for counting pulses taken from said transmission medium at the associated said one point to identify said time slots, means in each applique responsive to the count of its said first counter for controlling its sending access to its associated one of said audio communication channels, a second counter in each applique for counting pulses taken from said transmission medium at the associated said second point to identify said time slots, and means in each applique responsive to the count of its said second counter for controlling the receiving access of said applique to said audio communication channels.

In an electronic time-division-multiplexed communication system, the combination comprising:

• a lineal transmission medium including a communication line, means time dividing the usage of said communication line into a number of time-division-multiplexed communication channels over which information may be transmitted on said communication line, said means time dividing the usage of said communication line including means for transmitting on said lineal transmission medium and along with the information on said communication line a timing signal consisting of repetitive frames of pulses, which pulses divide each frame into a number of time slots, said time slots of each frame including at least one thereof assigned to signalling and supervision use and a plurality of others assigned to audio communication use, each time slot assigned to audio communication usage as repeated in repetitive frames defining one of a plurality of said communication channels referred to as audio communication channels and the at least one time slot assigned to signalling and supervision usage as repeated in repetitive frames defining another of the aforementioned communication channels referred to as a signalling and supervision communication channel, a plurality of appliques each connected to said communication line, means providing each of said appliques with sending access to one of said audio communication channels, means providing each of said appliques with receiving access to all of said audio communication channels and to said signalling and supervision channel, means connected with said communication line and having sending access to said signalling and supervision channel for inserting signalling and supervision messages into said signalling and supervision channel, means in each of said appliques for receiving and utilizing the information transmitted over said signalling and supervision channel, audio utilization means connected to each applique for utilizing the information transmitted on any one of said audio communication channels, and means in each applique responsive to the received signalling and supervision messages for controlling said receiving access of such applique to said audio communication channels to cause such applique to receive and pass to its audio utilization means only information appearing on an audio communication channel identified in a signalling and supervision message received by such applique.