Predetection signal compensation

Claim 2

Signal processing for an information-bearing signal having information cell periods, said information signal being subject to undesired perturbations, improved signal processing including the combination, generating first and second intermediate signals, said first signal being compensated for said undesired perturbations whether or not such perturbations actually exist in said information-bearing signal, analyzing said information-bearing signal at points spaced in time by said information cell period and selecting portions of said first and second intermediate signals as an output signal in accordance with predetermined characteristics of said information-bearing signal which indicate whether or not such undesired perturbations are likely to have occurred.

Claim 3

The signal processing set forth in claim 1 wherein said characteristic is amplitude comparisons of the information-bearing signal wherein a difference in amplitude dictates selection of the first compensated signal as the output signal.

Claim 4

The signal processing set forth in claim 1 wherein said undesired perturbation is peak-shift within said information-bearing signal, said first signal being continually compensated for said peak shift and said signal receiving no compensation.

Claim 5

The signal processing as set forth in claim 3 wherein said peak-shift compensation includes analog subtraction of a portion of a one-cell delayed signal and a current readback signal from a one-half-cell delayed signal such that during long one-half wavelengths in said information-bearing signal a baseline recovery may occur generating undesired zero crossovers, said second signal being said current information-bearing signal delayed in accordance with the processing time for said peak-shift compensation.

Claim 6

The signal processing set forth in claim 4 wherein said information-bearing signal is a readback signal in a magnetic media recording system and information is represented therein by transitions in signal states of recorded flux on said media, said readback including differentiating said readback signal for providing zero crossovers and hard limiting said signals subsequent to peak-shift compensation and before comparing same to generate a selection signal for selecting either a peak-shift compensated signal or a delayed uncompensated signal, said delayed uncompensated signal also being hard limited before being selected.

Claim 7

The signal processing set forth in claim 5 wherein said limited peak-shift compensated signal is selected whenever the polarity of the cell delayed signal and the undelayed signal are different and said uncompensated signal selected whenever the one-cell delayed signal and the current signal are the same.

Claim 8

The signal processing set forth in claim 6 wherein the selection of the uncompensated second signal overlaps the selection of the peak-shift compensated signal.

Claim 9

The signal processing set forth in claim 6 wherein the signals used for peak-shift compensation are derived in the same manner as for the selection signals.

Claim 10

The processing of an information-bearing signal having cell times defining successive information indicating portions, the improved signal processing including the combination, compensating said information-bearing signal for peak-shift errors resulting from undesired peak shift including processing said signal to produce a first intermediate signal having baseline crossover perturbations which may introduce false information into the signal, delaying said information-bearing signal by one of said cell durations, hard limiting said delayed signal, hard limiting said information-bearing signal, and EXCLUSIVE-OR comparing said one-cell time delayed hard limited signal and said other hard limited signal and selecting that peak-shift compensated signal as an output signal when the EXCLUSIVE-OR relationship is satisfied and selecting the one-cell delayed signal when said EXCLUSIVE-OR relationship is not satisfied.

Claim 11

The processing of an information-bearing signal having cell times defining successive information indicating portions, the improved signal processing including the combination, compensating said information-bearing signal for peak-shift errors resulting from undesired peak shift including processing said signal to produce a first intermediate signal having baseline crossover perturbations which may introduce false information into the signal, delaying said information-bearing signal by one of said cell durations, hard limiting said delayed signal, hard limiting said information-bearing signal, and EXCLUSIVE-OR comparing said one-cell time delayed hard limited signal and said other hard limited signal and selecting that peak-shift compensated signal as an output signal when the EXCLUSIVE-OR relationship is satisfied and selecting the one-cell delayed signal when said EXCLUSIVE-OR relationship is not satisfied.

Claim 12

Signal transition adjustment for an information-bearing signal having transitions of signal states and being subjected to undesired perturbations which alter the time of occurrence of transitions, the signal transition adjustment including the combination, defining a repetitive cell period duration for said information-bearing signal, adjusting transitions of said signal in accordance with changes in one-half wavelengths in said signal to generate a first intermediate signal having adjusted transitions, generating a second intermediate signal not having its transitions so adjusted, selecting transitions from either said first or second intermediate signal as information representing transitions in accordance with predetermined wavelength characteristics of said information-bearing signal and generating an output signal including said selected transitions.

Claim 13

Signal transition adjustment for an information-bearing signal having transitions of signal states and being subjected to undesired perturbations which alter the time of occurrence of transitions, the signal transition adjustment including the combination, defining a repetitive cell period duration for said information-bearing signal, adjusting transitions of said signal in accordance with changes in one-half wavelengths in said signal to generate a first intermediate signal having adjusted transitions, generating a second intermediate signal not having its transitions so adjusted, selecting transitions from either said first or second intermediate signal as information representing transitions in accordance with predetermined wavelength characteristics of said information-bearing signal and generating an output signal including said selected transitions.

Claim 14

The adjusting set forth in claim 10 wherein said wavelength determinations are made in accordance with said information signal being sampled at points spaced apart in accordance with said cell period durations.

Claim 15

A predetection signal processor for an information-bearing signal representing data encoded therein in successively occurring cell periods having predetermined durations, the improvement including the combination: cell period means supplying first, second, and third signals derived from said information-bearing signal respectively representing a current signal, a one-half period delayed signal and a full period delayed signal, respectively; compensation means receiving said first, second, and third signals and including arithmetic means for producing a first intermediate signal in accordance with predetermined amplitude relationships between said first, second, and third signals for compensating certain undesired perturbations but with generating possible other perturbations having a degrading effect on signal fidelity; means for converting said second signal to a second intermediate signal; gate signal generating means responsive to said first and third signals to generate gate signals indicating the EXCLUSIVE-OR signal polarity relationship thereof; gating means being responsive to said gate signals and said intermediate signals to supply an output signal for detection consisting of selected portions of said first intermediate signal when receiving an EXCLUSIVE-OR indication and portions of second intermediate signals when the EXCLUSIVE-OR relationship is not satisfied.

Claim 16

A predetection signal processor for an information-bearing signal representing data encoded therein in successively occurring cell periods having predetermined durations, the improvement including the combination: cell period means supplying first, second, and third signals derived from said information-bearing signal respectively representing a current signal, a one-half period delayed signal and a full period delayed signal, respectively; compensation means receiving said first, second, and third signals and including arithmetic means for producing a first intermediate signal in accordance with predetermined amplitude relationships between said first, second, and third signals for compensating certain undesired perturbations but with generating possible other perturbations having a degrading effect on signal fidelity; means for converting said second signal to a second intermediate signal; gate signal generating means responsive to said first and third signals to generate gate signals indicating the EXCLUSIVE-OR signal polarity relationship thereof; gating means being responsive to said gate signals and said intermediate signals to supply an output signal for detection consisting of selected portions of said first intermediate signal when receiving an EXCLUSIVE-OR indication and portions of second intermediate signals when the EXCLUSIVE-OR relationship is not satisfied.

Claim 17

The subject matter of claim 12 including separate limiter means electrically interposed respectively between said peak-shift compensation means and said gating means, between said cell period means and said gate generating means such that said gating means and said gate generating means operate in a digital manner.

Claim 18

The apparatus of claim 13 wherein said peak-shift compensation means have a predetermined circuit delay, delay means delaying said intermediate signal such that the second intermediate signal arrives in propEr phase relationship at said gating means with said peak-shift compensated signal, delay means in said gate generating means delaying said EXCLUSIVE-OR output signal such that it has the proper phase relationship with said peak-shift compensated signal, further delay means connected to said EXCLUSIVE-OR circuit and including inverter means for supplying a complement gate signal to said gating means for selectively gating said second intermediate signal as an output signal, said gating means including OR circuit means logically combining said gated peak-shift compensated signal and said gated second intermediate signal.

Claim 19

The apparatus set forth in claim 14 wherein said delay means for said gate signal supplies two time-spaced signals for supplying same with inversion as said complementary gate signal such that the gating means selects said second intermediate signal in an overlapping manner with respect to said first intermediate signal.

Claim 20

Subject matter set forth in claim 15 wherein said apparatus is in a magnetic media recording system, differentiating means supplying a differentiated information-bearing signal to said cell measurement means such that the output signal of said apparatus is a replica of the signal recorded in said magnetic recording system.

Claim 21

Apparatus set forth in claim 14 wherein said gate generating means includes gate signal widening means such that said selected portions of said intermediate signals overlap and including timing means for establishing said overlap in time-spaced relation to expected information-bearing signal state changes.