Magnetic recording and readback systems with raised cosine equalization

Claim 2

For a digital recording system using a linearized record of digital signals having bit periods of predetermined duration, an improved readback system, including the combination: a twice Nyquist bandwidth circuit for transferring readback signals therethrough from said linearized record; and filter means electrically associated with said circuit to adjust zero crossovers of said read-back signals in accordance with a raised cosine Alpha 1 function of said readback signals.

Claim 3

The system set forth in claim 1 further including a zero-crossover detection system receiving said readback signals from said circuit and responsive thereto for detecting digital signals therein in a self-clocking manner.

Claim 4

The system set forth in claim 2 wherein said filter means in said readback circuit only partially generates said raised cosine function and being adapted to compensate readback signals read from a linearized record having a partial raised cosine filtering effected thereon prior to or during generation of the record such that the two partial compensations result in an effective raised cosine function on said readback signals.

Claim 5

The system set forth in claim 2 further including additional filters for providing compensation other than said raised cosine filter in addition to said raised cosine filter means.

Claim 6

The system set forth in claim 4 wherein said additional filtering action includes an inverse sinc or whitening filter action means.

Claim 7

The system set forth in claim 4 wherein said additional filtering means is an inverse channel filter.

Claim 8

The system set forth in claim 6 further including inverse sinc filter means.

Claim 9

The system set forth in claim 2 wherein said raised cosine filter means is only partially in said readback means with the remainder being in a recording system for use to generate said linearized record whereby the effective raised cosine filtering action is the result of combining the prewrite compensation with the readback compensation.

Claim 10

The system set forth in claim 1 wherein said filter means establishes said raised cosine output signal to have one-half peak amplitude at approximately one-half of a bit period of said readback signal.

Claim 11

A readback system for a digital signal magnetic recording system with signal-processing means having filter action exhibiting raised cosine Alpha 1 characteristics for improving detectability of read-back signals in said system.

Claim 12

A readback system for a digital signal magnetic recording system with signal-processing means having filter action exhibiting raised cosine Alpha 1 characteristics for improving detectability of read-back signals in said system.

Claim 13

The system set forth in claim 10 furtHer including a self-clocking, zero-crossover detector receiving said readback signals from said filter means and including means generating a clock signal derived from the raised cosine compensated filter.

Claim 14

The system set forth in claim 10 wherein said signal-processing means further exhibits additional filter action for compensating said readback signals in addition to said raised cosine filtering action thereby adjusting zero crossovers more closely to a given constant periodicity and establishing a one-half peak amplitude at a one-half bit period of said readback signal.

Claim 15

Zero-crossing adjustment for a periodic signal being processed in a digital magnetic recording system having certain signal perturbing characteristics, including the steps of: adjusting such signals in accordance with the inverse of the magnetic recording system signal perturbing characteristics and effecting a raised cosine Alpha 1 filtering action on said signal.

Claim 16

Zero-crossing adjustment for a periodic signal being processed in a digital magnetic recording system having certain signal perturbing characteristics, including the steps of: adjusting such signals in accordance with the inverse of the magnetic recording system signal perturbing characteristics and effecting a raised cosine Alpha 1 filtering action on said signal.

Claim 17

The adjustment set forth in claim 13 and further applying an inverse sinc or whitening filter action to said signal.

Claim 18

The adjustment set forth in claim 12 further including linearizing the recording of signals on a magnetic record.

Claim 19

The adjustment set forth in claim 15 including detecting the filtered signals using zero-crossover detection techniques.

Claim 20

A digital magnetic recording system including means for receiving data signals to be recorded, prewrite compensation means partially compensating signals to be recorded in an analog manner in accordance with raised cosine characteristics, bias means receiving the partially filtered signals for adding a bias signal thereto, record signal amplifier means receiving the biased signals to be recorded and means for recording the biased signals on a magnetic media, means for detecting recorded signals and amplifying same, readback filter means receiving the amplified readback signals and adjusting the signals for zero crossover in a manner complementary to the prewrite compensation such that the output signal from said readback filter means has compensated the signals being processed in accordance with raised cosine characteristics, and detector means receiving the signals from said readback filter means for detecting same and indicating the digital representation of the readback recorded signal.

Claim 21

A digital magnetic recording system including means for receiving data signals to be recorded, prewrite compensation means partially compensating signals to be recorded in an analog manner in accordance with raised cosine characteristics, bias means receiving the partially filtered signals for adding a bias signal thereto, record signal amplifier means receiving the biased signals to be recorded and means for recording the biased signals on a magnetic media, means for detecting recorded signals and amplifying same, readback filter means receiving the amplified readback signals and adjusting the signals for zero crossover in a manner complementary to the prewrite compensation such that the output signal from said readback filter means has compensated the signals being processed in accordance with raised cosine characteristics, and detector means receiving the signals from said readback filter means for detecting same and indicating the digital representation of the readback recorded signal.

Claim 22

The record system set forth in claim 17 further including additional filtering action in said filter in accordance with recording channel characteristics.

Claim 23

The system set forth in claim 17 wherein said prewrite compensation compensates a signal in other than said raised cosine characteristics and said raised cosine characteristics filtering action is entirely provided by said readback filter.