High-speed pcm data-transmission system

Claim 2

A data-transmission system comprising: a central office provided with signal-receiving means and signal-transmitting means; a plurality of outlying stations each provided with datacommunication equipment and with a two-way signal path having an outgoing branch and an incoming branch extending from said equipment to said central office, the transmission paths associated with at least some of said stations having substantially different impedance criteria; a PCM terminal at said central office coupled to said signalreceiving and signal-transmitting means for establishing data links between stations; routing means at said central office operable to connect the outgoing and incoming branches of any signal path to said signal-transmitting and signal-receiving means, respectively, preparatorily to the establishment of a data link between a first station associated with the signal path and a second station reachable through said PCM terminal, said routing means including an equalization network with a plurality of filter circuits selectively insertable in series with said outgoing branch, said filter circuits substantially conforming to impedance criteria of different signal paths to minimize distortion; and processing means at said central office responsive to an identification signal from said first station to operate said routing means for insertion of a conforming filter circuit prior to inception of data transmission between said first and second stations.

Claim 3

A system as defined in claim 1 wherein said signal path is adapted for the transmission of analog signals and is provided at each end with a respective baseband modem for the conversion of binary code words into analog signals and vice versa.

Claim 4

A system as defined in claim 2 wherein each of said stations is provided with first timing means for establishing a predetermined transmission rate for outgoing signals and an operating speed at a fractional value of said transmission rate for the processing of data words leaving and entering said equipment, the transmission rates of at least some of said stations being different from but harmonically related to one another, said central office being provided with second timing means synchronizable with said first timing means at said transmission rate for processing code words arriving over and destined for a signal path connected thereto.

Claim 5

A system as defined in claim 3 wherein said central office is provided with memory means storing information on the impedance criteria and transmission rates of all signal paths connectable thereto and for reading out said information in response to saiD identification signal, said equalization network being divided into a plurality of sections containing respective groups of said filter circuits compatible with different transmission rates, said routing means including switch means responsive to transmission-rate information from said memory means for giving access to a section of said network compatible with the transmission rate of said first station and selector means responsive to impedance information from said memory means for inserting a conforming filter circuit of said compatible section in series with said outgoing branch.

Claim 6

A system as defined in claim 3 wherein said first timing means at said first station is adjustable for selecting one of several harmonically interrelated operating speeds, said first station being provided with a signal generator for emitting a speed code indicative of the selected operating speed to said central office for retransmission to said first station as a confirmation signal and for transmission to said second station, said first timing means being connected to said incoming branch for adjustment to the selected operating speed by said confirmation signal.

Claim 7

A system as defined in claim 5 wherein said signal generator is connected to said first timing means and to said equipment for synthesizing a succession of code words each consisting of a series of first bit positions allotted to message bits from said equipment and a series of second bit positions allotted to service bits, said first station further including selector means connected to said generator for producing said speed code in said second bit positions of a code word devoid of message bits in said first bit positions.

Claim 8

A system as defined in claim 6 wherein said first timing means includes a source of clock pulses counting three fourths of the total number of bit positions per code word for separating said first and second bit positions in the output of said generator.

Claim 9

A data-transmission system comprising: a central office provided with signal-receiving means and signal-transmitting means; a plurality of outlying stations each provided with data-communication equipment and with a two-way signal path having an outgoing branch and an incoming branch adapted for the transmission of analog signals; a first baseband modem linking said equipment with said signal path for converting binary code words from said equipment into analog signals transmitted over said outgoing branch and for converting analog signals received over said incoming branch into binary code words for said equipment; a second baseband modem connected to said signal path at said central office for converting analog signals from said outgoing branch into binary code words for said signal-receiving means and for converting binary code words from said signal-transmitting means into analog signals transmitted over said incoming branch; first timing means at each of said stations for establishing a transmission rate for outgoing code words, said transmission rate being different for at least some of said stations; a PCM terminal at said central office coupled to said signal-receiving and signal-transmitting means for establishing data links between stations; routing means at said central office operable to connect the outgoing and incoming branches of any signal path to said signal-transmitting and signal-receiving means, respectively, preparatorily to the establishment of a data link between a first station associated with a given signal path and second station reachable through said PCM terminal, said routing means including an equalization network with several sections selectively insertable in series with said outgoing branch to match the transmission rate of said first station; processing means at said central office for operating said routing means in response to an identification signal from said first station to insert a compatible section of said network in series with said outgoing branch pRior to inception of data transmission between said first and second stations; and second timing means at said central office controlled by said processing means for operation in step with said first timing means.

Claim 10

A data-transmission system comprising: a central office provided with signal-receiving means and signal-transmitting means; a plurality of outlying stations each provided with data-communication equipment and with a two-way signal path having an outgoing branch and an incoming branch adapted for the transmission of analog signals; a first baseband modem linking said equipment with said signal path for converting binary code words from said equipment into analog signals transmitted over said outgoing branch and for converting analog signals received over said incoming branch into binary code words for said equipment; a second baseband modem connected to said signal path at said central office for converting analog signals from said outgoing branch into binary code words for said signal-receiving means and for converting binary code words from said signal-transmitting means into analog signals transmitted over said incoming branch; first timing means at each of said stations for establishing a transmission rate for outgoing code words, said transmission rate being different for at least some of said stations; a PCM terminal at said central office coupled to said signal-receiving and signal-transmitting means for establishing data links between stations; routing means at said central office operable to connect the outgoing and incoming branches of any signal path to said signal-transmitting and signal-receiving means, respectively, preparatorily to the establishment of a data link between a first station associated with a given signal path and second station reachable through said PCM terminal, said routing means including an equalization network with several sections selectively insertable in series with said outgoing branch to match the transmission rate of said first station; processing means at said central office for operating said routing means in response to an identification signal from said first station to insert a compatible section of said network in series with said outgoing branch pRior to inception of data transmission between said first and second stations; and second timing means at said central office controlled by said processing means for operation in step with said first timing means.

Claim 11

A system as defined in claim 8 wherein said processing means includes a memory storing information on individual impedance criteria of different signal paths terminating at said central office, each of said sections including a plurality of filter circuits selectable by said routing means under the control of said memory for substantially conforming to the impedance criteria of a signal path having its outgoing branch connected to said signal-receiving means.

Claim 12

A system as defined in claim 8 wherein said first timing means includes an adjustable clock circuit for establishing an operating speed common to said first and second stations at a fractional value of their respective transmission rates for the processing of data words leaving and entering said equipment, each of said stations including a signal generator for synthesizing a succession of code words with a predetermined number of bit positions following one another at the respective transmission rate and for allocating certain of said bit positions to data bits from said equipment while reserving other of said bit positions for ancillary information including said identification signal.

Claim 13

A system as defined in claim 10 wherein said first timing means includes a pulsing circuit for counting a number of data bits, issuing from said equipment at a cadence determined by said operating speed, equal to the number of said certain of said bit positions and to fill a code word with said data bits upon completion of the count.

Claim 14

A system as defined in claim 11 wherein said operating speed is such a small fraction of the transmission rate of said first station that some of the code words originating at said second station are blanks devoid of data bits, said processing means including a descriminator for suppressing said blanks at an input end of the incoming branch of the signal path leading to said second station.