Signal multiplexing circuit

Abstract

The disclosed signal multiplexing circuit (110) makes use of a single pair of wires (T, R) to interface a data and voice communication circuit such as an electronic key telephone (EKT) station set (100) with a central data and voice communication system such as a communication system (BCS). The signal multiplexing circuit transmits outgoing standard voice signals, outgoing auxiliary signals and outgoing data and, in turn, simultaneously receives incoming standard voice signals, incoming data and incoming auxiliary signals on the single pair of wires. Both time division and frequency separation techniques are concurrently employed to achieve multiple use of the single pair of wires without crosstalk between the plurality of signals. The data signals are transmitted as bipolar bit pairs preceded by a data start pulse pair. The outgoing data bipolar bit pairs are delayed until the center transition of the incoming data bipolar pulse pair is detected. The first half of the incoming data bipolar pulse pair appears on the line undisturbed while the second half of the same pulse pair is "overwritten" by the first half of the outgoing data bipolar pulse pair.

I claim: 
     
       1. A signal multiplexing circuit for use between a central communication system and a remote communication circuit for concurrently transmitting outgoing voice signals, outgoing data, and outgoing auxiliary signals from said remote communication circuit to said central communication system via a communication path which comprises a single pair of wires, wherein said signal multiplexing circuit comprises: encoding means for converting said outgoing auxiliary signals into pulse coded signals;   isolation means for separating said outgoing voice signals, said outgoing data and said outgoing encoded auxiliary signals from each other in both frequency and time, and   transmitting means for transmitting said separated signals to said central communication system via said single pair of wires.   
     
     
       2. The invention of claim 1 wherein said signal multiplexing circuit additionally comprises: receiving means for receiving incoming voice signals, incoming data, and incoming encoded auxiliary signals, formatted identically to said outgoing voice signals, said outgoing data, said outgoing encoded auxiliary signals, and transmitted to said remote communication circuit via said single pair of wires;   separation means for separating said incoming voice signals from said incoming data and said incoming encoded auxiliary signals and applying said incoming voice signals to said remote communication circuit;   steering means for isolating said incoming data from said incoming encoded auxiliary signals and applying said incoming data to said remote communication circuit; and   decoding means for translating said incoming encoded auxiliary signals into analog signals and applying said analog signals to said remote communication circuit.   
     
     
       3. The invention of claim 2 wherein said separation means comprises a low pass filter. 
     
     
       4. The invention of claim 2 wherein said isolation means includes: frequency division means for separating said voice signals from both said data and said encoded auxiliary signals in frequency; and   time division means for separating said data from said encoded auxiliary signals in time.   
     
     
       5. The invention of claim 4 wherein said encoding means includes pulse width modulation means for transforming said auxiliary signals into pulse width modulation signals. 
     
     
       6. The invention of claim 5 wherein said decoding means comprises pulse width demodulation means for transforming said incoming encoded auxiliary signals into analog signals. 
     
     
       7. The invention of claim 4 wherein said transmitting means includes pulse code modulation means for transmitting said data as pulse code modulation bipolar pulse pairs. 
     
     
       8. The invention of claim 7 wherein said receiving means includes pulse code demodulation means for receiving said incoming data pulse code modulation bipolar pulse pairs. 
     
     
       9. The invention of claim 4 wherein said transmitting means begins transmitting said data while said receiving means is receiving said incoming data. 
     
     
       10. The invention of claim 4 wherein said transmitting means begins transmitting said outgoing encoded auxiliary signals while said receiving means is receiving said incoming encoded auxiliary signals. 
     
     
       11. A signal multiplexing circuit for concurrently transmitting outgoing voice signals, outgoing data, and outgoing auxiliary signals on a communication path comprising a single pair of wires, wherein said signal multiplexing circuit comprises: encoding means for converting said outgoing auxiliary signals into bipolar pulse pair signals;   formatting means for converting said outgoing data to bipolar pulse pair digital signals;   isolation means for separating said outgoing voice signals from both said formatted outgoing data and said outgoing encoded auxiliary signals in frequency;   time division means for separating said formatted outgoing data from said outgoing encoded auxiliary signals in time; and   transmitting means for transmitting said separated outgoing voice signals, formatted outgoing data and outgoing encoded auxiliary signals on said single pair of wires.   
     
     
       12. The invention of claim 11 wherein said signal multiplexing circuit includes reception means for concurrently receiving incoming voice signals, incoming formatted data and incoming encoded auxiliary signals, formatted identically to said outgoing voice signals, to said formatted outgoing data, to said outgoing encoded auxiliary signals respectively, from said single pair of wires wherein said reception means includes: separation means for separating said incoming voice signals from both said incoming formatted data and said incoming encoded auxiliary signals; steering means for isolating said incoming formatted data from said incoming encoded auxiliary signals;     decoding means for translating said incoming encoded auxiliary signals into analog auxiliary signals; and   reformatting means for translating said incoming formatted data comprising bipolar pulse pair digital signals to binary digital data.   
     
     
       13. The invention of claim 12 wherein said transmitting means transmits said formatted data beginning at the center pair transition of said incoming formatted data and wherein said transmitting means transmits said encoded auxiliary signals beginning at the center pair transition of said incoming encoded auxiliary signals. 
     
     
       14. The invention of claim 13 wherein said outgoing encoded auxiliary signals and said incoming endoded auxiliary signals comprise pulse width modulation bipoplar pulse pair signals; and wherein said incoming formatted data and said outgoing formatted data comprise pulse code modulation bipolar pulse pair digital signals.   
     
     
       15. A signal multiplexing system for use between a central communication system and a remote communication circuit for concurrently transmitting outgoing voice signals, outgoing data, and outgoing auxiliary signals bidirectionally between said remote communication circuit and said central communication system via a communication path which comprises a single pair of wires wherein said signal multiplexing system comprises an interface circuit for connecting said remote communication circuit to said single pair of wires and for connecting said central communication system to said single pair of wires, wherein said interface circuit comprises: encoding means for converting said outgoing auxiliary signals into pulse coded signals;   isolation means for separating said outgoing voice signals, said outgoing data and said outgoing encoded auxiliary signals from each other in both frequency and time, and   transmitting means for concurrently transmitting said separated signals on said single pair of wires.   
     
     
       16. The invention of claim 15 wherein said interface circuit additionally comprises: receiving means for concurrently receiving incoming voice signals, incoming data and incoming encoded auxiliary signals;   separation means for separating said incoming voice signals from both said incoming data and said incoming encoded auxiliary signals;   steering means for isolating said incoming data from said incoming encoded auxiliary signals; and   decoding means for translating said incoming encoded auxiliary signals into analog signals. .Iadd.17. A signal multiplexing circuit for concurrently transmitting a plurality of signals on a communication path comprising:   isolation means responsive to said plurality of signals for separating a first subset of said plurality of signals from the remainder of said plurality of signals in frequency and a second subset of said plurality of signals from the remainder of said plurality of signals in time;   transmitting means responsive to said isolation means for concurrently transmitting two or more of said signals at a time on to said communication path. .Iaddend. .Iadd.18. The invention of claim 17 wherein said signal multiplexing circuit includes:   means for receiving a plurality of incoming signals separated from each other in frequency and time and concurrently transmitted to said signal multiplexing circuit on said communication path. .Iaddend. .Iadd.19. The invention of claim 18 wherein said signal multiplexing circuit includes:   means for separating said plurality of incoming signals from each other. .Iaddend. .Iadd.20. The invention of claim 19 wherein said signal multiplexing circuit includes:   encoding means responsive to said plurality os signals for encoding one or more of said plurality of signals; and   wherein said isolation means is responsive to said encoded signals for separating each of said encoded signals from every other one of both said   
     
     
        encoded signals and said plurality of signals. .Iaddend. .Iadd.21.  The invention of claim 20 wherein said signal multiplexing circuit includes: means responsive to said incoming signals for decoding the encoded ones of said incoming signals. .Iaddend. .Iadd.22. A method of multiplexing a plurality of signals on a communication pair comprising the steps of:   separating a first subset of said plurality of signals from the remainder of said plurality of signals in frequency and a second subset of said plurality of signals from the remainder of said plurality of signals in time; and   combining all of said separated signals into a single data stream. .Iaddend. .Iadd.23. The invention of claim 22 wherein said method of multiplexing a plurality of signals on a communication pair includes the step of:   transmitting said single data stream on to said communication pair. .Iaddend. .Iadd.24. The invention of claim 23 wherein said step of separating includes the step of:   encoding the ones of said plurality of signals which are inappropriately formatted for separation from every other one of said plurality of signals..Iaddend. .Iadd.25. The invention of claim 24 wherein said step of encoding includes the step of:   converting analog signals to digital signals. .Iaddend. .Iadd.26. A signal multiplexing circuit for concurrently transmitting a plurality of signals on a communication path comprising:   frequency division means responsive to said plurality of signals for separating a first subset of said plurality of signals from the remainder of said plurality of signals in frequency;   time division means responsive to said plurality of signals for separating each of said signals in said first subset from every other one of said signals in said subset in time and for separating each one of said remainder signals from every other one of said remainder signals in time; and   means responsive to said frequency division means and to said time division means for concurrently transmitting said plurality of frequency and time separated signals on to said communication path. .Iaddend. .Iadd.27. A signal multiplexing circuit for concurrently transmitting a plurality of signals on a communication path comprising:   frequency division means responsive to said plurality of signals for separating a first subset of said plurality of signals from the remainder of said plurality of signals in frequency;   time division means responsive to said plurality of signals for separating each of said remainder signals from every other one of said remainder signals in time;   means responsive to said frequency division means and to said time division means for concurrently transmitting said plurality of frequency and time   
     
     
        separated signals on to said communication path. .Iaddend. .Iadd.28.  The invention of claim 26 or 27 wherein said signal multiplexing circuit includes: encoding means responsive to said plurality of signals for encoding one or more of said plurality of signals into digital form. .Iaddend.