Data storage and decoding apparatus

Claim 2

A data storage medium, comprising a plurality of bit cells for storing data bits of a NRZ data word and clock information bits; groups of n data bits of the NRZ data word each being stored over n consecutive bit cells, respectively; and a clock information bit being stored between said groups at every n+1 bit cell.

Claim 3

A data storage medium, according to claim 1, wherein n=2.

Claim 4

A data storage medium, according to claim 1 or 2,wherein said clock information bit has a logic level which is the opposite of the logic level of the data bit of the bit cell next preceding said clock information bit.

Claim 5

A magnetic data storage tape for use in a high shock and vibration environment, comprising: a plurality of bit cells for storing data bits and clock information bits; a plurality of digital words being formatted on the magnetic data storage tape, each digital word including i) 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 ii) a clock information bit stored between each said group of n data bits at every n+1 bit cell, said clock information bit having a logic level transition so that the logic level of said clock information bit is the opposite of the logic level of the data bit of the bit cell next preceding said clock information bit.

Claim 6

A magnetic data storage tape for use in a high shock and vibration environment, comprising: a plurality of bit cells for storing data bits and clock information bits; a plurality of digital words being formatted on the magnetic data storage tape, each digital word including i) 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 ii) a clock information bit stored between each said group of n data bits at every n+1 bit cell, said clock information bit having a logic level transition so that the logic level of said clock information bit is the opposite of the logic level of the data bit of the bit cell next preceding said clock information bit.

Claim 7

A magnetic data storage tape, according to claim 4, wherein n=2.

Claim 8

Apparatus for decoding digital data stored on a data storage medium (10),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 (20)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; b) means (30) foroutputting the digital data in response to the analog signal; and c) means(52),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.

Claim 9

Apparatus for decoding digital data stored on a data storage medium (10),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 (20)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; b) means (30) foroutputting the digital data in response to the analog signal; and c) means(52),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.

Claim 10

Apparatus, according to claim 6, wherein the analog signal has relatively positive and negative levels, and wherein said means for outputting the digital data comprises: a) means (33,38,44) for generating a reference signal tracking the average of the positive and negative levels of the analog signal; and b) means (48)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.

Claim 11

Apparatus, according to claim 7, wherein said means for generating a reference signal comprises: a) firstmeans (33)for sampling the positive levels of the analog signal to provide a sampled positive level signal; b) second means (38)for sanpling the negative levels of the analog signal to provide a sampled negative level signal; and c) means (44) for summing the sampled positive level signal and the sampled negative level signal.

Claim 12

Apparatus, according to claim 8 wherein said first means for sampling comprises: a) a positive level sampler (33); and b) means (50)responsive to the output pulses, for generating enabling signals to enable said positive level sampler.

Claim 13

Apparatus, according toclaim 8 or 9, wherein said second means for sampling comprises: a) a negative level sampler (38); and b) means (50)responsive to the output pulses, for generating enabling signals to enable said negative level sampler.

Claim 14

Apparatus, according to any of claims 6 to 10, wherein the analog signal has relatively positive and negative levels, and wherein said means(52) for producing and inhibiting the data-ready pulses comprises: a) means(50) for generating transition pulses upon the transitions of the digital data being outputted between positive and negative levels; b) controllablemeans(60) for producing a pulse train waveform in response to the transition pulses; c) neans(74) for generating the data ready pulses in response to the pulse train waveform; and d) means(70) for detecting each clock information bit in response to the pulse train waveform, said detecting means (70)disabling said data ready pulse generatingneans(74) upon detecting the clock information bit and enabling said data ready pulse generating means in the absence of detecting each clock information bit.

Claim 15

Apparatus, according to claim 11, wherein said controllable means for producing a pulse train waveform comprises: a) a voltage controlled oscillator (60) for generating the pulse train waveform; b) means (70) for generating an enabling signal at a time related to the occurrence of each clock information bit; and c) neans(58), enabled in response to the enabling signal, for detecting which pulse occurs first between one of the transition pulses and one of the pulses of the pulse train waveform to produce an error signal, said voltage controlled oscillator being controlled in response to the error signal, and said voltage controlled oscillator resetting the pulse train waveform upon the absence of one of the transition pulses within a maximum time or resetting the pulse train waveform in response to the occurrence of one of the pulses within the maximum time.

Claim 16

Apparatus for decoding NRZT digital data stored on a magnetic data storage tape(12) 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 z 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(20) 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 analoghaving relatively positive and negative levels; b) means(30) for reconstructing the NRZT digital data stored on the tape in response to the analog signal, including i) means(33,38,44) for generating a reference signal tracking the average of the positive and negative levels of the analog signal; and ii) means (48) 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(52), 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 clock intormation bit, including i) means (50) for generating transition pulses upon the transitions of the output logical pulses between the logical 0 and 1 levels; ii) controllable means(60) for producing a pulse train waveform in response to the transition pulses; iii) means(74) for generating the data ready pulse in response to the pulse train waveform; and iv) means(70) 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.

Claim 17

Apparatus for decoding NRZT digital data stored on a magnetic data storage tape(12) 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 z 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(20) 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 analoghaving relatively positive and negative levels; b) means(30) for reconstructing the NRZT digital data stored on the tape in response to the analog signal, including i) means(33,38,44) for generating a reference signal tracking the average of the positive and negative levels of the analog signal; and ii) means (48) 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(52), 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 clock intormation bit, including i) means (50) for generating transition pulses upon the transitions of the output logical pulses between the logical 0 and 1 levels; ii) controllable means(60) for producing a pulse train waveform in response to the transition pulses; iii) means(74) for generating the data ready pulse in response to the pulse train waveform; and iv) means(70) 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.

Claim 18

Apparatus, according to claim 13, wherein said means for generating a reference signal comprises: a) a positive level sampler(33) for sampling the positive levels of the analog signal to provide a sampled positive level signal; b) 4 negative level sampler (38)for sampling the negative levels of the analog signal to provide a sampled negative level signal; c) a transition pulse generator (50), responsive to the output pulses, for generating enabling signals to enable said positive level sampler and said negative level sampler, respectively; and d) a summer(44) for averaging the sampled positive level signal and the sampled negative level signal.

Claim 19

Apparatus, according to claim 13 or 14, wherein said controllable means for producing a pulse train waveform comprises: a) a phase resettable voltage controlled oscillator (60) for outputting the pulse train waveform at a controlled pulse repetition frequency; b) a clock transition detector (70) for generating an enabling signal at a time related to the time of occurrence of each clock information bit; and c) a timing error detector(58),being enabled in response to the enabling signal, for producing an error signal in response to an earlier pulse of one of the transition pulses of said pulse transition generating means and one of the pulses of the pulse train waveform, the controlled pulse repetition frequency of said resettable voltage controlled oscillator being adjustable in response to the error signal.

Claim 20

Apparatus, according to claim 15, wherein said clock transition detector comprises a modulo counter.

Claim 21

Apparatus, according to claim 16, wherein said modulo counter is a modulo 3 counter.

Claim 22

Apparatus, according to any of claims 13 to 17, wherein the magnetic data storage tape further stores a plurality of synchronization bits stored, respectively, over a plurality of the bit cells, and wherein said means (70) for detecting each clock information bit is synchronized in response to the plurality of synchronization bits.