Adaptive system for correction of distortion of signals in transmission of digital data

Claim 2

Digital data apparatus comprising: means for receiving digital data signals; signal correction means coupled to said receiver means for subtracting a correction signal from signals being received to produce corrected received signals; digital storage means coupled to said signal correction means for digital storage of data in said corrected received signals; and residual distortion detection means including correlation means coupled to said digital storage means to provide a correlator output corresponding to the current data being received, said residual distortion detection means being responsive to said correlator output and said corrected received signal to provide a signal indicative of residual distortion in said corrected received signal, said correlator means being responsive to said residual signal and prior digital data stored in said storage means to provide said correction signal for said signal correction means.

Claim 3

A digital data transmission system comprising: a transmitter for transmitting digital data signals; a receiver for said signals including means for storage of said digital data; a correction circuit means for subtracting s correction signal from said signals being received and for coupling corrected received signals to said storage means; residual distortion detection means coupled to said correction circuit means for detection of any remaining distortion in said corrected received signals to produce a residual distortion signal; and correlation means having inputs coupled to storage means and to said residual detection means for correlating stored digital data and said residual distortion signal to produce a correction signal corrEsponding to the distortion in the signals being received, said correlation means having a correlator output coupled to said correction means for applying said correction signal to said correction circuit means to produce said corrected signals.

Claim 4

A digital data transmission system comprising: a transmitter for transmitting digital data signals; a receiver for said signals including means for storage of said digital data; a correction circuit means for subtracting s correction signal from said signals being received and for coupling corrected received signals to said storage means; residual distortion detection means coupled to said correction circuit means for detection of any remaining distortion in said corrected received signals to produce a residual distortion signal; and correlation means having inputs coupled to storage means and to said residual detection means for correlating stored digital data and said residual distortion signal to produce a correction signal corrEsponding to the distortion in the signals being received, said correlation means having a correlator output coupled to said correction means for applying said correction signal to said correction circuit means to produce said corrected signals.

Claim 5

An adaptive system for correcting for distortion of a signal containing digital data and transmitted via a modulation system wherein a portion of said data is transmitted on a first channel and another portion of said data is transmitted on a second channel, said adaptive system comprising in combination: receiving means for providing a corresponding received signal in each channel; a first storage register having n cells for storing the most recent n data bits received on said fist channel, n being an integer greater than one; comparison means provided for each channel for detecting any distortion remaining in the respective received signals after correction for distortion to produce an output residual signal; means for producing a correction signal comprising; n first correlators, each associated with a corresponding cell of said first storage register, each of said first correlator comprising multiplier means for digitally mutiplying said output with the datum contained in said corresponding cell of said first shift register, and means for integrating the output signal of said multiplier means; a second storage register having m cells for storing the most recently received m data bits received on said second channel, m being an integer greater than one; m second correlators, each associated with a corresponding cell of said second shift register, each of said second correlators comprising; multiplier means for digitally multiplying said output of said first signal sample means with the datum contained in said corresponding cell of said second shift register, and means for integrating the output signal from said multiplier means; m first digital multipliers, each associated with a corresponding one of said first correlators and each comprising means for deriving an output having an amplitude equal to said integrated output signal from said corresponding first correlator and having a sign determined by the datum contained in said corresponding cell of said second storage register; m second digital multipliers, each associated with a corresponding one of said second correlators and each comprising means for deriving an output having an amplitude equal to said integrated output signal for said corresponding second correlator and having a sign determined by the datum contained in said corresponding cell of said second storage register; and means for summing the outputs from each of said first and second digital multipliers to provide said correction signal.

Claim 6

An adaptive system for correcting for distortion of a signal containing digital data and transmitted via a modulation system wherein a portion of said data is transmitted on a first channel and another portion of said data is transmitted on a second channel, said adaptive system comprising in combination: receiving means for providing a corresponding received signal in each channel; a first storage register having n cells for storing the most recent n data bits received on said fist channel, n being an integer greater than one; comparison means provided for each channel for detecting any distortion remaining in the respective received signals after correction for distortion to produce an output residual signal; means for producing a correction signal comprising; n first correlators, each associated with a corresponding cell of said first storage register, each of said first correlator comprising multiplier means for digitally mutiplying said output with the datum contained in said corresponding cell of said first shift register, and means for integrating the output signal of said multiplier means; a second storage register having m cells for storing the most recently received m data bits received on said second channel, m being an integer greater than one; m second correlators, each associated with a corresponding cell of said second shift register, each of said second correlators comprising; multiplier means for digitally multiplying said output of said first signal sample means with the datum contained in said corresponding cell of said second shift register, and means for integrating the output signal from said multiplier means; m first digital multipliers, each associated with a corresponding one of said first correlators and each comprising means for deriving an output having an amplitude equal to said integrated output signal from said corresponding first correlator and having a sign determined by the datum contained in said corresponding cell of said second storage register; m second digital multipliers, each associated with a corresponding one of said second correlators and each comprising means for deriving an output having an amplitude equal to said integrated output signal for said corresponding second correlator and having a sign determined by the datum contained in said corresponding cell of said second storage register; and means for summing the outputs from each of said first and second digital multipliers to provide said correction signal.

Claim 7

The adaptive system defined in claim 3 further comprising means for subtracting said correction signal from said signal received from said first channel to derive a corrected signal.

Claim 8

Means for correcting received digital data signals; subtraction means receiving as one input said received digital data signals; signal correction means for providing a correction signal to said subtraction means for subtraction from said received signals whereby the difference between said received digital data signals and said correction signal is the desired corrected received signal; means for storing the most recently corrected received signal in the form of most recently received data bits, including the current received data bit; means for correlating the most recently stored corrected signal against a residual signal to provide correction signals to said signal correction means; second subtraction means for subtracting the stored current data bit from said corrected received signal to form a residual signal which residual signal is fed to said means for correlating.

Claim 9

Means for correcting received digital data signals; subtraction means receiving as one input said received digital data signals; signal correction means for providing a correction signal to said subtraction means for subtraction from said received signals whereby the difference between said received digital data signals and said correction signal is the desired corrected received signal; means for storing the most recently corrected received signal in the form of most recently received data bits, including the current received data bit; means for correlating the most recently stored corrected signal against a residual signal to provide correction signals to said signal correction means; second subtraction means for subtracting the stored current data bit from said corrected received signal to form a residual signal which residual signal is fed to said means for correlating.

Claim 10

The invention according to claim 5 wherein said means for storing is an n cell register for storing the most recently received n data bits including the current data being received wherein n is an integer greater than two; and wherein said means for correlating is comprised of: n correlators, each associated with a corresponding cell of said storage register, each correlator comprising; multiplier means for digitally multiplying said residual signal with the datum contained in said corresponding cell, and means for integrating the output signal for said multiplier means.

Claim 11

The means for correcting defined in claim 6 wherein n is at least as great as the number of data bits transmitted during the ring out of said impulse response plus an additional correlator for determining the amplitude of the current data bit.

Claim 12

The means for correcting defined in claim 6 wherein said multiplier means comprise means for providing an output signal equal in amplitude to said output at predetermined intervals of each of the bit periods and having a sign corresponding to that of said output if the datum in said corresponding cell is true and opposite to that of said output if said datum is false.

Claim 15

The circuit arrangement defined in claim 9 in which said output of the multiplier for the current data bit it compared with the corrected signal to determined the residual distortion in the corrected signal to produce a residual signal for inputs of said correlators.

Claim 16

In conjunction with a multilevel modulation system, the circuit arrangement defined in claim 9 wherein said stored data bits comprise the most significant bits of said digital data.

Claim 17

The circuit arrangement as defined in claim 9 further comprising digital decision means for providing a binary output the sense of which is determined by the sign of said corrected received signal.