Interface circuit for digital signal transmission system
First Claim
1. An interface circuit for digital signal transmission system for use between first and second digital signaling devices, each device being operative to provide digital device signals of first, second and third characteristics, said digital signal transmission system comprising:
- first and second line interface devices connected to said first and second digital signaling devices, respectively;
a transmission line connected between said first and second line interface devices;
each of said first and second line interface devices being operative in response to said digital device signal of said first characteristic to provide bias current in said transmission line; and
each being further operative in response to said digital device signals of said second and third characteristics to modulate said bias current with modulation signals of first and second characteristics, respectively; and
each of said first and second line interface devices being further operative in response to said bias current to provide a digital interface signal of a first characteristic and each being further operative in response to said modulation signals of said first and second characteristics to provide digital interface signals of second and third characteristics, respectively;
said digital signaling devices each being further operative to receive said digital interface signals of said first, second and third characteristics.
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Accused Products
Abstract
A signal transmission system which allows digital signals to be transmitted over twisted pair transmission lines. Master and slave transmission circuits are located at the switching system and terminal ends, respectively, of the transmission line. Both circuits include transmit and receive circuitry. The transmit circuitry includes a summing circuit connected to a constant current generator and the receive circuit includes a differential amplifier connected to a slicer circuit.
109 Citations
24 Claims
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1. An interface circuit for digital signal transmission system for use between first and second digital signaling devices, each device being operative to provide digital device signals of first, second and third characteristics, said digital signal transmission system comprising:
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first and second line interface devices connected to said first and second digital signaling devices, respectively; a transmission line connected between said first and second line interface devices; each of said first and second line interface devices being operative in response to said digital device signal of said first characteristic to provide bias current in said transmission line; and
each being further operative in response to said digital device signals of said second and third characteristics to modulate said bias current with modulation signals of first and second characteristics, respectively; and
each of said first and second line interface devices being further operative in response to said bias current to provide a digital interface signal of a first characteristic and each being further operative in response to said modulation signals of said first and second characteristics to provide digital interface signals of second and third characteristics, respectively;
said digital signaling devices each being further operative to receive said digital interface signals of said first, second and third characteristics. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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Specification