Signal recovery system utilizing amplitude comparison at the beginning and end of a bit period

Claim 2

A signal recovery circuit for a digital signal magnetic recording system supplying a readback signal having successive bit periods, each for one bit of data, and indicative of recorded data signals represented and having harmonically related first and second signal components, wherein said first signal component has the lower of the two frequencies, said second signal component having an integral number of cycles in each bit period, the improvement including the combination, linear differencing means having first and second differential inputs and supplying an output signal linearly representative of the difference in signal amplitudes at said inputs, first linear means responsive to said readback signal for supplying a first signal amplitude substantially linearly related to the amplitude of said readback signal, second linear means responsive to said readback signal for supplying a second signal amplitude substantially linearly related to the amplitude of said readback signal, but delayed by one bit period with respect to said first signal amplitude, such that said differencing means supplies said output signal at least being representative of the difference in amplitude of said readback signal at the beginning and end of said bit periods, and detection means receiving said output signal for amplitude detecting same to indicate wHich of said signal components occurred during a given bit period.

Claim 3

The circuit of claim 1, further including clocking means for supplying successively occurring clock pulses of short duration in timed relation to said readback signal for defining the beginning and ends of said bit periods, and said detection means being enabled to be responsive to said output signal only during occurrence of said clock pulses.

Claim 4

A data recovery system for recovering data signals recorded in a magnetic media and for converting same to digital electrical signals indicative of such recorded data signals, one bit of digital data being readable from said magnetic media in one bit period, the improvement including the combination: linear signal translation means including transducer means for being operatively associated with said magnetic media for generating first and second readback signals from said magnetic media, each said readback signal having first and second harmonically related signal components and shifts therebetween representative of said recorded data signals, said first readback signal having a continuous predetermined phase delay relationship to said second readback signal in accordance with duration of one of said bit periods; linear signal processing means receiving said first and second readback signals for linearly differentially comparing same and including linear means responsive to said differential comparison for producing a third signal substantially consisting of undulations based upon only one of said signal components and all undulations thereof being of the same signal polarity with respect to a given reference potential; clock means supplying gate pulses in timed relation to said undulations; signal detection means receiving said third signal, said gate pulses, and establishing a voltage amplitude threshold for supplying output data pulses upon the coincidence of said third signal exceeding said voltage reference threshold during the receipt of a gate pulse.

Claim 5

A data recovery system for recovering data signals recorded in a magnetic media and for converting same to digital electrical signals indicative of such recorded data signals, one bit of digital data being readable from said magnetic media in one bit period, the improvement including the combination: linear signal translation means including transducer means for being operatively associated with said magnetic media for generating first and second readback signals from said magnetic media, each said readback signal having first and second harmonically related signal components and shifts therebetween representative of said recorded data signals, said first readback signal having a continuous predetermined phase delay relationship to said second readback signal in accordance with duration of one of said bit periods; linear signal processing means receiving said first and second readback signals for linearly differentially comparing same and including linear means responsive to said differential comparison for producing a third signal substantially consisting of undulations based upon only one of said signal components and all undulations thereof being of the same signal polarity with respect to a given reference potential; clock means supplying gate pulses in timed relation to said undulations; signal detection means receiving said third signal, said gate pulses, and establishing a voltage amplitude threshold for supplying output data pulses upon the coincidence of said third signal exceeding said voltage reference threshold during the receipt of a gate pulse.

Claim 6

The system of claim 3, wherein said transducer means includes a reproducing transducer having a pair of recorded signal recovering gaps spaced apart by one bit cell, one of said gaps being for detecting magnetic flux one bit period after the other, and first and second winding means in said reproducing transducer respectively associated with said recorded signal recovering gaps and for respectively supplying said first and second readback signals to said linear signal processing means.

Claim 7

The system of claim 3, wherein said linear signal translation means includes a linear amplifier receiving an initial readback signal from said transducer means for supplying said first readback signal, and linear signal delay means receiving said first readback signal and operative to supply said second readback signal one bit period after said first readback signal.

Claim 8

A signal recovery circuit for a magnetic recording system having a relatively moving magnetic media recording data in bit cells each scannable in a bit period, for recovering recorded digital data signals as a readback signal having successive bit periods each for one bit of data and indicative of recorded data signals represented and having harmonically related first and second signal components wherein said first signal component has the lower of the two frequencies, said second signal component having an integral number of cycles in a bit period and said first signal component having a nonintegral number of cycles in a bit period, only one of said signal components occurring in a given bit period, the improvement including the combination, clock means supplying successive first and second clock signals of short duration respectively indicative of the beginning and end of said given bit period, first and second means responsive to said readback signal to supply electrical signals having an amplitude substantially linearly related to the amplitude of said readback signal respectively during said first and second clock signals, differencing means receiving said electrical signals from said first and second means and jointly responsive thereto to supply a difference signal during occurrence of said second clock signal having a substantial amplitude only when said first signal component is present, and an insubstantial amplitude only when said second signal component is present in said given bit period.

Claim 9

A signal recovery circuit for a magnetic recording system having a relatively moving magnetic media recording data in bit cells each scannable in a bit period, for recovering recorded digital data signals as a readback signal having successive bit periods each for one bit of data and indicative of recorded data signals represented and having harmonically related first and second signal components wherein said first signal component has the lower of the two frequencies, said second signal component having an integral number of cycles in a bit period and said first signal component having a nonintegral number of cycles in a bit period, only one of said signal components occurring in a given bit period, the improvement including the combination, clock means supplying successive first and second clock signals of short duration respectively indicative of the beginning and end of said given bit period, first and second means responsive to said readback signal to supply electrical signals having an amplitude substantially linearly related to the amplitude of said readback signal respectively during said first and second clock signals, differencing means receiving said electrical signals from said first and second means and jointly responsive thereto to supply a difference signal during occurrence of said second clock signal having a substantial amplitude only when said first signal component is present, and an insubstantial amplitude only when said second signal component is present in said given bit period.

Claim 10

Signal recovery for a digital signal magnetic recording system which supplies a readback signal having successive bit periods and being indicative of binary data signals in that it has harmonically related first and second signal components respectively indicative of two signal states, said first signal component having the lower of the two frequencies while the second signal component has an integral number of cycles occurring in each bit period, improved signal recovery including the following steps in combination: obtaining the signal amplitudes at the beginning and end of a given bit period, linearly comparing said obtained amplitudes and indicating said first signal component when the amplitude difference is substantial and indicating the second signal component when amplitude difference is not substantial.

Claim 11

Signal recovery for a digital signal magnetic recording system which supplies a readback signal having successive bit periods and being indicative of binary data signals in that it has harmonically related first and second signal components respectively indicative of two signal states, said first signal component having the lower of the two frequencies while the second signal component has an integral number of cycles occurring in each bit period, improved signal recovery including the following steps in combination: obtaining the signal amplitudes at the beginning and end of a given bit period, linearly comparing said obtained amplitudes and indicating said first signal component when the amplitude difference is substantial and indicating the second signal component when amplitude difference is not substantial.

Claim 12

Signal recovery, as set forth in claim 7, wherein the readback signal is delayed by one of said bit periods and then amplitude compared with the current readback signal amplitude, and defining said bit period boundaries by the peaks in the readback signal portion from said first signal component.

Claim 13

A data recovery system for recovering data signals recorded on a magnetic media and for converting signals read back from the media to digital electrical signals indicative of such recorded data, said signals being readable from said magnetic media in successive bit period intervals, the improvement including the combination: linear signal translation means including transducer means for being operatively associated with the magnetic media for generating first and second readback signals from said magnetic media, each said readback signal having first and second harmonically related signal components and shifts therebetween representative of data, said first readback signal having a continuous predetermined phase delay relationship to said second readback signal in accordance with the duration of said successive bit periods, linear signal processing means receiving said first and second readback signals and linearly differentially comparing same and supplying an output signal having one of said harmonically signal components accentuated and a second one of said harmonically related signal components substantially eliminated, and amplitude detection means responsive to said third signal for indicating when the third signal exceeds a predetermined amplitude threshold indicative of a predetermined data content in an associated bit period.

Claim 14

A data recovery system for recovering data signals recorded on a magnetic media and for converting signals read back from the media to digital electrical signals indicative of such recorded data, said signals being readable from said magnetic media in successive bit period intervals, the improvement including the combination: linear signal translation means including transducer means for being operatively associated with the magnetic media for generating first and second readback signals from said magnetic media, each said readback signal having first and second harmonically related signal components and shifts therebetween representative of data, said first readback signal having a continuous predetermined phase delay relationship to said second readback signal in accordance with the duration of said successive bit periods, linear signal processing means receiving said first and second readback signals and linearly differentially comparing same and supplying an output signal having one of said harmonically signal components accentuated and a second one of said harmonically related signal components substantially eliminated, and amplitude detection means responsive to said third signal for indicating when the third signal exceeds a predetermined amplitude threshold indicative of a predetermined data content in an associated bit period.