Transversal equalizer for use in double sideband quadrature amplitude modulated system

Claim 2

A transversal equalizer for correcting the delay and attenuation distortion of an input signal defined by a plurality of digital words, comprising: a plurality of shift registers sequentially receiving the digital words in the input signal; multiplying means coupled to the shift registers and responsive solely to partial response detected digital data signals to provide the multiplying means with respective multiplying coefficients for multiplying the digital words stored in the associated shift registers to provide a plurality of products; and adding means coupled to each of the multipliers for adding the products provided by the multipliers to provide an equalized signal substantially free of the delay and attenuation distortion.

Claim 3

The equalizer recited in claim 1 wherein the input signal sequentially received by the shift registers is a double-sideband quadrature amplitude modulated signal.

Claim 4

The equalizer set forth in claim 1 wherein the multiplier means is solely responsive to (1,1) partial response detected digital data signals to provide the multiplying coefficients.

Claim 5

The transversal equalizer recited in claim 1 wherein both the input signal and the equalized signal have noncoherent characteristics so that the equalizer operates in a noncoherent domain.

Claim 6

An equalization correction network adapted for use with a double-sideband amplitude modulated modem including a demodulator providing data samples and a detector providing partial response detected data signals in each of an in-phase channel and a quadrature channel, the equalization correction network comprising: first means for sequentially storing a plurality of the data samples in the in-phase channel; second means for sequentially storing a plurality of the data samples in the quadrature channel; third means for multiplying each of the data samples in the first means by one of a series of in-phase digital coefficients to provide a first plurality of in-phase products and for multiplying each of the data samples in the second means by the series of in-phase digital coefficients to provide a first plurality of quadrature products; fourth means for multiplying each of the data samples in the first means by one of a series of quadrature digital coefficients to provide a second plurality of in-phase products and for multiplying each of the data samples in the second means by the series of quadrature coefficients to provide a second plurality of quadrature products; fifth means for adding the first plurality of in-phase products from the third means and the second plurality of in-phase products from the fourth means to provide an equalized digital signal in the in-phase channel; and sixth means for differentially adding the first plurality of quadrature products from the third means and the second plurality of quadrature products from the fourth means to provide an equalized digital signal in the quadrature channel.

Claim 7

An equalization correction network adapted for use with a double-sideband amplitude modulated modem including a demodulator providing data samples and a detector providing partial response detected data signals in each of an in-phase channel and a quadrature channel, the equalization correction network comprising: first means for sequentially storing a plurality of the data samples in the in-phase channel; second means for sequentially storing a plurality of the data samples in the quadrature channel; third means for multiplying each of the data samples in the first means by one of a series of in-phase digital coefficients to provide a first plurality of in-phase products and for multiplying each of the data samples in the second means by the series of in-phase digital coefficients to provide a first plurality of quadrature products; fourth means for multiplying each of the data samples in the first means by one of a series of quadrature digital coefficients to provide a second plurality of in-phase products and for multiplying each of the data samples in the second means by the series of quadrature coefficients to provide a second plurality of quadrature products; fifth means for adding the first plurality of in-phase products from the third means and the second plurality of in-phase products from the fourth means to provide an equalized digital signal in the in-phase channel; and sixth means for differentially adding the first plurality of quadrature products from the third means and the second plurality of quadrature products from the fourth means to provide an equalized digital signal in the quadrature channel.

Claim 8

The equalization correction network recited in claim 5 wherein the data samples in both the in-phase and quadrature channels as well as the equalized signals in both the in-phase and quadrature channels have noncoherent characteristics so that the equalization network operates in a noncoherent domain.

Claim 9

The equalization network recited in claim 5 further comprising: control means responsive to the partial response detected data signal provided by the detector for varying at least one of the multiplying coefficients in the series of in-phase digital multiplying coefficients of the third means and for varying at least one of the multiplying coefficients in the series of quadrature digital multiplying coefficients of the fourth means.

Claim 10

The equalization network set forth in claim 7 wherein the control means comprises: seventh means responsive to the equalized signal in the in-phase channel and the partial response detected signal in the in-phase channel to provide a first error term; eighth means responsive to the equalized signal in the quadrature channel and the partial response detected signal in the quadrature channel to provide a second error term; ninth means responsive to the equalized signal in the quadrature channel and the partial response detected signal in the in-phase channel to provide a third error term; tenth means responsive to the equalized signal in the in-phase channel and the partial response detected signal in the quadrature channel to provide a fourth error term; eleventh means responsive to at least one of the first error term of the seventh means and the second error term of the eighth means to vary at least one of the in-phase coefficients of the third means; and twelfth means responsive to at least one of the third error term of the ninth means and the fourth error term of the tenth means to vary at least one of the quadrature coefficients of the fourth means.

Claim 11

The equalization network recited in claim 8 wherein: the first, second, third and fourth error terms each have one of first characteristics indicating that the associated multiplying coefficient shoUld be higher in magnitude, second characteristics indicating that the associated multiplying coefficient should be lower in magnitude, and third characteristics indicating that the magnitude of the associated multiplying coefficient should not be changed; the eleventh means is responsive to the first and second error terms to increment at least one of the in-phase multiplying coefficients at least one step when one of the first and second error terms has the first characteristics and neither of the first and second error terms has the second characteristics, and to decrement at least one of the in-phase multiplying coefficients at least one step when one of the first and second error terms has the second characteristics and neither of the first and second error terms has the first characteristics; and the twelfth means is responsive to the third and fourth error terms to increment at least one of the quadrature multiplying coefficients at least one step when one of the third and fourth error terms has the first characteristics and neither of the third or fourth error terms has the second characteristics, and to decrement at least one of the quadrature multiplying coefficients at least one step when one of the third and fourth error signals has the second characteristics and neither of the third and fourth error terms has the first characteristics.

Claim 12

The equalization network recited in claim 9 wherein: the eleventh means is responsive to the first and second error terms both having the first characteristics to increment at least one of the in-phase multiplying coefficients by more than one step, and is responsive to the first and second error terms both having the second characteristics to decrement at least one of the in-phase multiplying coefficients by more than one step; and the twelfth means is responsive to the third and fo fourth error terms both having the first characteristics to increment at least one of the quadrature multiplying coefficients by more than one step, and is responsive to the third and fourth error signals both having the second characteristics to decrement at least one of the quadrature multiplying coefficients by more than one step.

Claim 13

An equalization network adapted for use in a double-sideband quadrature amplitude modulated system having an in-phase channel and a quadrature channel for correcting at least one of asymmetrical and symmetrical delay and attenuation distortion of transmitted data to provide an equalized signal in each of the in-phase channel and the quadrature channel, comprising: equalization means including at least one multiplier providing a plurality of variable coefficients for multiplying the data to correct for at least one of the symmetrical and asymmetrical distortion in at least one of the in-phase and quadrature channels; a control network providing at least a first error term having characteristics dependent upon a first group of the data and a second error term having characteristics dependent upon a second group of the data independent of the first group of the data, the first and second error terms being correlated to provide for the adjustment of the multiplying coefficients of the equalizer means.

Claim 14

An equalization network adapted for use in a double-sideband quadrature amplitude modulated system having an in-phase channel and a quadrature channel for correcting at least one of asymmetrical and symmetrical delay and attenuation distortion of transmitted data to provide an equalized signal in each of the in-phase channel and the quadrature channel, comprising: equalization means including at least one multiplier providing a plurality of variable coefficients for multiplying the data to correct for at least one of the symmetrical and asymmetrical distortion in at least one of the in-phase and quadrature channels; a control network providing at least a first error term having characteristics dependent upon a first group of the data and a second error term having characteristics dependent upon a second group of the data independent of the first group of the data, the first and second error terms being correlated to provide for the adjustment of the multiplying coefficients of the equalizer means.

Claim 15

The network recited in claim 11 wherein the control network is responsive to (1,1) partial response detected data signals to provide the first and second error terms.