Browse Prior Art Database

Magnetic Recording and Readback Systems

IP.com Disclosure Number: IPCOM000077544D
Original Publication Date: 1972-Aug-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 3 page(s) / 33K

Publishing Venue

IBM

Related People

Armitage, JD: AUTHOR [+2]

Abstract

The detectability of readback signals in a digital magnetic-recording system is enhanced, by employing a filtering technique effecting raised cosine output signal characteristics.

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Magnetic Recording and Readback Systems

The detectability of readback signals in a digital magnetic-recording system is enhanced, by employing a filtering technique effecting raised cosine output signal characteristics.

The figure is an abbreviated diagrammatic showing of a recording system which may use the present technique.

In this recording system, data to be recorded in digital form is supplied by data source 10 through compensating filter 11. Filter 11 may be matched with the filter in the readback system for effecting desired channel characteristics. Filter 11 supplies the compensated signal which may include low-pass signal characteristics to linear mixer 16. Mixer 16 receives a bias signal from source 15 and linearly adds it to the signal to be recorded. Amplifier 12 takes the biased signal and records the same on a multitrack media 9 through write transducer 13.

For each track, a separate read head 20 senses the flux permutations in media 9 and supplies a readback signal through amplifier 21 to compensating filter 22.

Filter 22 supplies the compensated signals to detector and clock 23. Detector 23 receives the digital information from the recording signal using zero-crossover detection. The clocking portion of detector 23 tracks the frequency and phase of the compensated signal. The detected information is asynchronously provided by detector 23 to deskewing apparatus 24. Deskewing apparatus 24 adjusts the time in the various record track signal channels to form bytes of data. The bytes are checked by ECC circuit 25 for error and possible correction. Correct data is then supplied to output system 26.

When the readback signal is adjusted to ideal components, a zero-axis cross detector easily generates a clocking signal from the precise and regular zero crossings. When such a detector operates from the phase-shifted readback signal, the time perturbations in zero-axis crossings make it difficult to generate a clocking signal.

Operation of the illustrated digital recording system, is enhanced by enabling a narrow bandwidth recording system with up to fully compensated zero crossovers in the readback signal.

In the present sys...