Data encoding and decoding scheme
First Claim
1. Apparatus for decoding digital data stored on a data storage medium, the digital data including a NRZ data word having groups of n data bits, each group being stored over n consecutive bit cells, respectively, and including a clock information bit stored between said groups at every n+1 bit cell, comprising:
- (a) means for reading the digital data stored on the data storage medium and for producing an analog signal corresponding to the n data bits and the clock information bit, wherein the analog signal has positive and negative levels;
(b) means for outputting the digital data in response to the analog signal, including(i) means for generating a reference signal tracking the average of the positive and negative levels of the analog signal; and
(ii) means for comparing the analog signal with the reference signal and for generating output pulses upon transitions, respectively, of the analog signal going above or below the reference signal, the output pulses being the outputted digital data; and
(c) means, responsive to the digital data being outputted, for producing data-ready pulses at a time corresponding to the bit cells storing the n data bits and for inhibiting the data-ready pulses at a time corresponding to the bit cell storing the clock information bit.
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Abstract
Digital data formatted on a data storage medium, in which the medium has a plurality of bit cells and the data format is such that groups of n data bits of an N-bit data word are stored over n consecutive bit cells, respectively, and a clock information bit is stored between the groups at every n+1 bit cell. A decoding apparatus includes circuitry for reading the digital data and producing an analog signal corresponding to the n data bits and the clock information bit, circuitry for reconstructing the digital data in response to the analog signal, and circuitry for producing data-ready pulses at a time corresponding to the bit cells storing the n data bits and for inhibiting the data-ready pulses at a time corresponding to the bit cell storing the clock information bit.
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Citations
12 Claims
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1. Apparatus for decoding digital data stored on a data storage medium, the digital data including a NRZ data word having groups of n data bits, each group being stored over n consecutive bit cells, respectively, and including a clock information bit stored between said groups at every n+1 bit cell, comprising:
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(a) means for reading the digital data stored on the data storage medium and for producing an analog signal corresponding to the n data bits and the clock information bit, wherein the analog signal has positive and negative levels; (b) means for outputting the digital data in response to the analog signal, including (i) means for generating a reference signal tracking the average of the positive and negative levels of the analog signal; and (ii) means for comparing the analog signal with the reference signal and for generating output pulses upon transitions, respectively, of the analog signal going above or below the reference signal, the output pulses being the outputted digital data; and (c) means, responsive to the digital data being outputted, for producing data-ready pulses at a time corresponding to the bit cells storing the n data bits and for inhibiting the data-ready pulses at a time corresponding to the bit cell storing the clock information bit. - View Dependent Claims (2, 3, 4)
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5. Apparatus for decoding digital data stored on a data storage medium, the digital data including a NRZ data word having groups on n data bits, each group being stored over n consecutive bit cells, respectively, and including a clock information bit stored between said groups at every n+1 bit cell, comprising:
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(a) means for reading the digital data stored on the data storage medium and for producing an analog signal corresponding to the n data bits and the clock information bit;
wherein the analog signal has positive and negative levels;(b) means for outputting the digital data in response to the analog signal; and (c) means, responsive to the digital data being outputted, for producing data-ready pulses at a time corresponding to the bit cells storing the n data bits and for inhibiting the data-ready pulses at a time corresponding to the bit cell storing the clock information bit, including (i) means for generating transition pulses upon the transitions of the analog signal between the positive and negative levels; (ii) controllable means for producing a pulse train waveform in response to the transition pulses; (iii) means for generating the data-ready pulses in response to the pulse train waveform; and (iv) means for detecting each clock information bit in response to the pulse train waveform, said detecting means disabling said data-ready pulse generating means upon detecting the clock information bit and enabling said data-ready pulse generating means in the absence of detecting each clock information bit. - View Dependent Claims (6)
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7. Apparatus for decoding NRZT digital data stored on a magnetic data storage tape usable in a high shock and vibration environment, the magnetic data storage tape having a plurality of bit cells and the NRZT digital data including an NRZ data word having at least one group of n data bits stored over n consecutive bit cells, respectively, in which n≧
- 2, and a clock information bit stored between each group of n data bits at every n+1 bit cell, the clock information bit having a logic level transition so that the logic level of the clock information bit is the opposite of the logic level of the data bit of the bit cell next preceding the clock information bit, the apparatus comprising;
(a) means for reading the NRZT digital data stored on the magnetic data storage tape and for producing an analog signal corresponding to the NRZT digital data, the analog signal having positive and negative levels; (b) means for reconstructing the NRZT digital data stored on the tape in response to the analog signal, including (i) means for generating a reference signal tracking the average of the positive and negative levels of the analog signal; and (ii) means for comparing the analog signal with the reference signal and for generating output logical 1 level and logical 0 level pulses upon transitions, respectively, of the analog signal going above and below the reference signal, the output logical pulses being substantially the same as the NRZT digital data; and (c) means, responsive to the output logical pulses, for producing data-ready pulses at a time corresponding to the bit cells storing the n data bits and for inhibiting the data-ready pulses at a time corresponding to the bit cells storing the lock information bit, including (i) means for generating transition pulses upon the transitions of the analog signal between the positive and negative levels; (ii) controllable means for producing a pulse train waveform in response to the transition pulses; (iii) means for generating the data ready pulses in response to the pulse train waveform; and (iv) means for detecting each clock information bit in response to the pulse waveform, said detecting means disabling said data ready pulse generating means upon detecting each clock information bit and enabling said data ready pulse generating means in the absence of detecting each clock information bit. - View Dependent Claims (8, 9, 10, 11, 12)
- 2, and a clock information bit stored between each group of n data bits at every n+1 bit cell, the clock information bit having a logic level transition so that the logic level of the clock information bit is the opposite of the logic level of the data bit of the bit cell next preceding the clock information bit, the apparatus comprising;
Specification