Triplex digital magnetic recording and reproducing system
AssigneeSperry Corporation
InventorChao S. Chi
Life of this patent
Estimating the term…
Abstract
A quaternary saturated digital magnetic recording system for enhancing information entropy provides an effective bit density increase of 100% or more over the MFM code. In the simplest implementation, groups of two input binary bits are mapped into one data cell, preferably into four combinations of long or short breaks and positive or negative polarity, with the break optionally centralized within the data cell for self-clocking. A system for reproducing the recorded information provides a peak detector, responsive to the recorded signal, coupled to pulse polarity and break width detector circuitry, with an internally synchronized clock, for remapping the recorded data into binary format.
Claims17
A magnetic recording system for recording information on a magnetic medium, comprising:
- means for generating a substantially continuous alternating signal,
- means for applying said alternating signal to provide a multiplicity of magnetic flux reversals that substantially erases said magnetic medium,
- means for providing an interruption of said alternating signal at a controlled polarity and position thereof,
- said interruption comprising a break of predetermined duration corresponding to said controlled polarity embedded in said alternating signal,
- means coupled to said alternating signal for controlling the duration of said break by selecting at least two of a plurality of predetermined durations, and
- means for receiving and recording said interrupted alternating signal on said medium,
- said controlled polarity being defined by the direction of said alternating signal at the time of initiating said interruption, and said alternating signal being resumed after said break in an opposing polarity defined by the direction of said alternating signal at the time of resumption, said time of initiating said interruption and said time of resumption bounding said break corresponding to one of said predetermined durations.
Apparatus for recording information on a magnetic medium, comprising:
- means for receiving input binary bits,
- binary data storage means for receiving binary data words each including at least two of said input binary data bits,
- digital control means coupled to said binary data storage means and responsive to said data words for producing digital control signals each representative of one of a predetermined plurality of alternating flux reversal signal and break patterns,
- pattern storage means for storing said plurality of alternating flux reversal signal and break patterns, comprising a first pattern represented by a long break of positive polarity between said alternating signals, a second pattern represented by a narrow break of positive polarity between said alternating signals, a third pattern represented by a narrow break of negative polarity between said alternating signals, and a fourth pattern represented by a wide break of negative polarity between said alternating signals, wherein each of said breaks is centrally disposed within said pattern,
- pattern selection means coupled to receive control signals from said digital control means and alternating signal and break patterns from said pattern storage means for selecting at least one of said patterns for producing a train of encoded binary data comprising pulses of predetermined widths and polarities responsive to said alternating signal, said break width, and said polarity, including means for storing said train of binary data in parallel form and reading out said train as binary data in serial form,
- means for receiving a pulse from binary clock means for synchronizing said binary data storage means, divider means, and phase-lock-oscillator clock means,
- divider means responsive to said binary clock means for providing a pulse for synchronizing said digital control means and delay means thereto,
- said delay means comprising means for delaying said divider synchronizing pulse by a predetermined time with respect to said binary clock means synchronization pulse, and for providing a delayed synchronization pulse to said clock and said pattern selection means, said phase-lock oscillator clock means responsive to said delay means and said binary clock means, for supplying timing signals to said means for storing binary data in parallel form and reading out said data in serial form, and
- write amplifier means for driving a recording head and responsive to said serial data.
Dependencies are inferred from the claim text.