Digital data transmission system with adaptive predistortion of transmitted pulses

Claim 2

In a digital data transmission system of the type comprising a digital data transmitter connected to at least one receiver by a metallic transmission medium, said receiver configured to receive a signal comprising a plurality of pulses, each characterized by a predetermined pulse shape, the improvement comprising: means, associated with the transmitter, for monitoring a transmission characteristic of the medium and automatically classifying the metallic transmission medium into one of a plurality of categories in accordance with the monitored transmission characteristic; means, included in the transmitter, for shaping a data signal comprising a string of pulses to one of a plurality of alternative pulse shapes, at least some of which deviate from the predetermined pulse shape in a manner effective to predistort the transmitted pulses to enhance correspondence between (1) the transmitted pulse as received by the receiver after distortion by the transmission medium and (2) the predetermined pulse shape; means, responsive to the classifying means and connected to the shaping means, for automatically controlling the shaping mean to select one of the plurality of alternative pulse shapes to correspond to the category in which the transmission medium is classified by the classifying means; and means, included in the transmitter, for transmitting on the metallic transmission medium the data signal as shaped by the shaping means; wherein the shaping means comprises: a delay line having at least one data input terminal coupled to receive the data signal and a plurality of output terminals, said delay line operative to apply the data signal with a respective delay as a respective output signal at each of the output terminals of the delay line; a plurality of banks of resistors, each resistor within a bank connectable to a respective one of the output terminals to weight the respective output signal by a respective weighting factor, each bank associated with a respective one of the alternate pulse shapes; and means for summing the weighted output signals to synthesize a summed output signal characterized by the selected one of the plurality of alternative pulse shapes.

Claim 3

The invention of claim 1 wherein the plurality of alternative pulse shapes comprises first and second alternative pulse shapes, and wherein the first and second alternative pulse shapes deviate from the predetermined pulse shape and from one another.

Claim 4

The invention of claim 1 wherein the monitoring means comprises an automatic gain control circuit coupled to the transmission medium.

Claim 5

The invention of claim 1 wherein the delay line comprises: a digital transversal filter comprising at least one clock input terminal, and a plurality of stages which are clocked by signals applied to the clock input terminal to shift digital data through the stages, at least selected stages each providing a respective output; and a clock signal source connected to the clock input terminal to apply at least one clock signal thereto.

Claim 6

The invention of claim 1 wherein the summing means comprises a summing node connected to the plurality of resistors.

Claim 7

The invention of claim 1 wherein the automatically selecting means comprises means for selectively connecting any one of the banks of resistors to respective ones of the output terminals.

Claim 8

The invention of claim 1 wherein the transmission medium comprises a twisted pair of conductors.

Claim 9

The invention of claim 1 wherein the predetermined pulse shape is a compressed duobinary shape.

Claim 10

The invention of claim 1 wherein the transmitting means transmits the transmitted pulses at a rate in excess of 10 MBS.

Claim 11

In a digital data transmission system of the type comprising a digital data transmitter connected to at least one receiver by a metallic transmission medium, said receiver configured to receive a signal comprising a plurality of pulses, each characterized by a predetermined pulse shape, the improvement comprising: a classification circuit associated with the transmitter, coupled to the metallic transmission medium and operative to monitor at least one transmission characteristic of the medium and to classify the medium into one of a plurality of categories in accordance with a monitored transmission characteristic of the medium; a pulse shaping circuit, included in the transmitter, operative to shape a data signal comprising a string of pulses to one of a plurality of alternative pulse shapes, at least some of which deviate from the predetermined pulse shape in a manner effective to predistort the transmitted pulses to enhance correspondence between (1) the transmitted pulse as received by the receiver after distortion by the transmission medium and (2) the predetermined pulse shape; a selection circuit responsive to the classification circuit and connected to the shaping circuit, to automatically control the shaping circuit to select one of the plurality of alternative pulse shapes to correspond to the category in which the transmission medium is classified by the classification circuit; and means, included in the transmitter, for transmitting on the metallic transmission medium the data signal as shaped by the shaping means; wherein the pulse shaping circuit comprises: a delay line having at least one data input terminal coupled to receive the data signal and a plurality of output terminals, said delay line operative to apply the data signal with a respective delay as a respective output signal at each of the output terminals of the delay line; a plurality of banks of resistors, each resistor within a bank connectable to a respective one of the output terminals to weight the respective output signal by a respective weighting factor, each bank associated with a respective one of the alternate pulse shapes; and means for summing the weighted output signals to synthesize a summed output signal characterized by the selected one of the plurality of alternative pulse shapes.

Claim 12

In a digital data transmission system of the type comprising a digital data transmitter connected to at least one receiver by a metallic transmission medium, said receiver configured to receive a signal comprising a plurality of pulses, each characterized by a predetermined pulse shape, the improvement comprising: a classification circuit associated with the transmitter, coupled to the metallic transmission medium and operative to monitor at least one transmission characteristic of the medium and to classify the medium into one of a plurality of categories in accordance with a monitored transmission characteristic of the medium; a pulse shaping circuit, included in the transmitter, operative to shape a data signal comprising a string of pulses to one of a plurality of alternative pulse shapes, at least some of which deviate from the predetermined pulse shape in a manner effective to predistort the transmitted pulses to enhance correspondence between (1) the transmitted pulse as received by the receiver after distortion by the transmission medium and (2) the predetermined pulse shape; a selection circuit responsive to the classification circuit and connected to the shaping circuit, to automatically control the shaping circuit to select one of the plurality of alternative pulse shapes to correspond to the category in which the transmission medium is classified by the classification circuit; and means, included in the transmitter, for transmitting on the metallic transmission medium the data signal as shaped by the shaping means; wherein the pulse shaping circuit comprises: a delay line having at least one data input terminal coupled to receive the data signal and a plurality of output terminals, said delay line operative to apply the data signal with a respective delay as a respective output signal at each of the output terminals of the delay line; a plurality of banks of resistors, each resistor within a bank connectable to a respective one of the output terminals to weight the respective output signal by a respective weighting factor, each bank associated with a respective one of the alternate pulse shapes; and means for summing the weighted output signals to synthesize a summed output signal characterized by the selected one of the plurality of alternative pulse shapes.

Claim 13

The invention of claim 10 wherein the plurality of alternative pulse shapes comprises first and second alternative pulse shapes, and wherein the first and second alternative pulse shapes deviate from the predetermined pulse shape and from one another.

Claim 14

The invention of claim 10 wherein the classification circuit comprises an automatic gain control circuit coupled to the transmission medium.

Claim 15

The invention of claim 10 wherein the delay line comprises: a digital transversal filter comprising at least one clock input terminal, ad a plurality of stages which are clocked by signals applied to the clock input terminal to shift digital data through the stages, at least selected stages each providing a respective output; and a clock signal source connected to the clock input terminal to apply at least one clock signal thereto.

Claim 16

The invention of claim 10 wherein the summing means comprises a summing node connected to the plurality of resistors.

Claim 17

The invention of claim 10 wherein the selection circuit comprises means for selectively connecting any one of the banks of resistors to respective ones of the output terminals.

Claim 18

The invention of claim 10 wherein the transmission medium comprises a twisted pair of conductors.

Claim 19

The invention of claim 10 wherein the predetermined pulse shape is a compressed duobinary shape.

Claim 20

The invention of claim 10 wherein the transmitter transmits the transmitted pulses at a rate in excess of 10 MBS.

Claim 21

The invention of claim 10 wherein the transmission medium comprises a metallic transmission medium.

Claim 22

In a digital data transmission system of the type comprising a digital data transmitter connected to at least one receiver by a metallic transmission medium, said receiver configured to receive a signal comprising a plurality of pulses, each characterized by a predetermined compressed duobinary pulse shape, the improvement comprising: means, associated with the transmitter, for monitoring a transmission characteristic of the medium and automatically classifying the metallic transmission medium into one of a plurality of categories in accordance with the monitored transmission characteristic; means, included in the transmitter, for shaping a data signal comprising a string of pulses to one of a plurality of alternative pulse shapes, at least some of which deviate from the predetermined compressed duobinary pulse shape in a manner effective to predistort the transmitted pulses to enhance correspondence between (1) the transmitted pulse as received by the receiver after distortion by the transmission medium and (2) the predetermined compressed duobinary pulse shape; means, responsive to the classifying means and connected to the shaping means, for automatically controlling the shaping means to select one of the plurality of alternative pulse shapes to correspond to the category in which the transmission medium is classified by the classifying means; and means, included in the transmitter, for transmitting on the metallic transmission medium the data signal as shaped by the shaping means.

Claim 23

In a digital data transmission system of the type comprising a digital data transmitter connected to at least one receiver by a metallic transmission medium, said receiver configured to receive a signal comprising a plurality of pulses, each characterized by a predetermined compressed duobinary pulse shape, the improvement comprising: means, associated with the transmitter, for monitoring a transmission characteristic of the medium and automatically classifying the metallic transmission medium into one of a plurality of categories in accordance with the monitored transmission characteristic; means, included in the transmitter, for shaping a data signal comprising a string of pulses to one of a plurality of alternative pulse shapes, at least some of which deviate from the predetermined compressed duobinary pulse shape in a manner effective to predistort the transmitted pulses to enhance correspondence between (1) the transmitted pulse as received by the receiver after distortion by the transmission medium and (2) the predetermined compressed duobinary pulse shape; means, responsive to the classifying means and connected to the shaping means, for automatically controlling the shaping means to select one of the plurality of alternative pulse shapes to correspond to the category in which the transmission medium is classified by the classifying means; and means, included in the transmitter, for transmitting on the metallic transmission medium the data signal as shaped by the shaping means.

Claim 24

In a digital data transmission system of the type comprising a digital data transmitter connected to at least one receiver by a metallic transmission medium, said receiver configured to receive a signal comprising a plurality of pulses, each characterized by a predetermined pulse shape, the improvement comprising: a classification circuit associated with the transmitter, coupled to the metallic transmission medium and operative to monitor at least one transmission characteristic of the medium and to classify the medium into one of a plurality of categories in accordance with a monitored transmission characteristic of the medium; a pulse shaping circuit, included in the transmitter, operative to shape a data signal comprising a string of pulses to one of a plurality of alternative pulse shapes, at least some of which deviate from the predetermined pulse shape in a manner effective to predistort the transmitted pulses to enhance correspondence between (1) the transmitted pulse as received by the receiver after distortion by the transmission medium and (2) the predetermined pulse shape; a selection circuit responsive to the classification circuit and connected to the shaping circuit, to automatically control the shaping circuit to select one of the plurality of alternative pulse shapes to correspond to the category in which the transmission medium is classified by the classification circuit; and means, included in the transmitter, for transmitting on the metallic transmission medium the data signal as shaped by the shaping means.

Claim 25

In a digital data transmission system of the type comprising a digital data transmitter connected to at least one receiver by a metallic transmission medium, said receiver configured to receive a signal comprising a plurality of pulses, each characterized by a predetermined pulse shape, the improvement comprising: a classification circuit associated with the transmitter, coupled to the metallic transmission medium and operative to monitor at least one transmission characteristic of the medium and to classify the medium into one of a plurality of categories in accordance with a monitored transmission characteristic of the medium; a pulse shaping circuit, included in the transmitter, operative to shape a data signal comprising a string of pulses to one of a plurality of alternative pulse shapes, at least some of which deviate from the predetermined pulse shape in a manner effective to predistort the transmitted pulses to enhance correspondence between (1) the transmitted pulse as received by the receiver after distortion by the transmission medium and (2) the predetermined pulse shape; a selection circuit responsive to the classification circuit and connected to the shaping circuit, to automatically control the shaping circuit to select one of the plurality of alternative pulse shapes to correspond to the category in which the transmission medium is classified by the classification circuit; and means, included in the transmitter, for transmitting on the metallic transmission medium the data signal as shaped by the shaping means.