US3569948A
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US
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High bit density record and reproduce system with selected frequency band component dispersal
Assignee: Subscription Television Inc
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Filing: 1967-08-23
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Granted: 1971-03-09
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Expires: 1987-08-23
Abstract
Abstract A method and apparatus is disclosed which avoids bit dropout and dropin problems associated in magnetic medium recording by resolving the random multilevel signal inputs characteristic of digital data into a plurality of selected frequency band components. These selected frequency band components are each subjected to a different time delay which relative time delays are selected at random. A signal summation circuit sums the delayed frequency band components and the summation signal is recorded in assigned spaces on a single data track on a magnetic medium as a slowly varying nonsaturable analogue signal. This method and apparatus as disclosed thus disperses in a single data track the information content of several data bits over a considerable length of the magnetic medium rather than confining them to sequential bit cell intervals. Accordingly, any spurious signal variation for a short duration of time, as normally characterized by a dropout or a dropin, results in a loss of only a few frequency cycles of several frequency band components which compose the information content of many data bits with the result being that extremely high bit rates are possible with virtually no probability of a bit dropout or a bit dropin. Reproduction of the binary data is accomplished through the use of a complementary frequency band dispersive circuit. In a further nonlimiting embodiment wherein the magnetic medium may vary in speed relative to the record and reproduce circuits, an intermediate record and reproduce device is employed which is responsive to such speed variations so as to continually assure precise spatial separation of the frequency band components on the magnetic medium.
Inventors
- 👤 Kermit A Norris
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 14:20
CPC Classifications
G; G11; G11B; G11B20/00; G11B20/10; G11B20/18
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
176 words
Apparatus for reducing recording errors for a sequential train of information-representing binary data having a bit cell period which is substantially equal to or less than the duration of spurious electrical noise signals and the duration of surface imperfections on a magnetic storage medium adapted for relative movement adjacent a magnetic recording head, said apparatus comprising: means for receiving an input train of binary data and deriving therefrom a plurality of frequency band components which together constitute the binary data input train; a plurality of delay means, one each for each one of the plurality of frequency band components, said delay means adapted to delay each frequency band component by an arbitrary amount independent of and distinct from the amount of delay for all other frequency band components; a magnetic recording head adapted to record an analogue signal on a single track of said magnetic storage medium; and a signal summation circuit having an input connected in common to said delay means and an output for applying a composite analogue signal to said magnetic record head.
Claim 2
Dependent Claim
176 words
Apparatus for reducing recording errors for a sequential train of information-representing binary data having a bit cell period which is substantially equal to or less than the duration of spurious electrical noise signals and the duration of surface imperfections on a magnetic storage medium adapted for relative movement adjacent a magnetic recording head, said apparatus comprising: means for receiving an input train of binary data and deriving therefrom a plurality of frequency band components which together constitute the binary data input train; a plurality of delay means, one each for each one of the plurality of frequency band components, said delay means adapted to delay each frequency band component by an arbitrary amount independent of and distinct from the amount of delay for all other frequency band components; a magnetic recording head adapted to record an analogue signal on a single track of said magnetic storage medium; and a signal summation circuit having an input connected in common to said delay means and an output for applying a composite analogue signal to said magnetic record head.
Claim 3
Dependent Claim
85 words
Apparatus in accordance with claim 1 wherein said input train receiving means comprises: an input terminal for receiving said data input train; a plurality of selective band-pass filters each having a filter input connected in common with the other filter inputs and also connected in common to said input terminal; and a filter output individually connecting each filter to one of said plurality of delay means for providing said independent and distinct delay times to signals passed through each one of said plurality of filters.
Claim 4
Dependent Claim
129 words
Apparatus for reducing recording errors for a sequential train of information-representing binary data having a bit cell period which is substantially equal to or less than the duration of spurious electrical noise signals and the duration of surface imperfections on a magnetic storage medium, said apparatus comprising: input means for receiving train of binary data; driving means connected to said input means for deriving from said data train a plurality of frequency band signals each of which is displaced in time an arbitrarily chosen distinct amount from the other frequency band signals and all of which together in nondisplaced order constitute the binary data input train; and recording means connected to said deriving means for recording a composite signal formed from said displaced signals on a magnetic storage medium.
Claim 5
Dependent Claim
129 words
Apparatus for reducing recording errors for a sequential train of information-representing binary data having a bit cell period which is substantially equal to or less than the duration of spurious electrical noise signals and the duration of surface imperfections on a magnetic storage medium, said apparatus comprising: input means for receiving train of binary data; driving means connected to said input means for deriving from said data train a plurality of frequency band signals each of which is displaced in time an arbitrarily chosen distinct amount from the other frequency band signals and all of which together in nondisplaced order constitute the binary data input train; and recording means connected to said deriving means for recording a composite signal formed from said displaced signals on a magnetic storage medium.
Claim 6
Dependent Claim
52 words
Apparatus for reproducing data recorded in accordance with claim 3 wherein said reproducing apparatus comprises: means for recovering said composite signal from said magnetic storage medium; and means connected to said recovery means for rederiving said plurality of frequency band components in nondisplaced order to constitute said original binary data input train.
Claim 7
Dependent Claim
33 words
Apparatus in accordance with claim 4 wherein said rederiving means comprises a plurality of pass band filters each having pass band characteristics matched to coincide with the pass bands of said deriving means.
Claim 8
Dependent Claim
61 words
Apparatus in accordance with claim 5 wherein said rederiving means further comprises a plurality of delay means each having delay times which complement the displacement times of said deriving means, with each complement delay time being associated with one filter having a pass band matched to the frequency band signal which received a displacement time complementary thereto in said deriving means.
Claim 9
Dependent Claim
67 words
Apparatus in accordance with claim 3 wherein said frequency band signal deriving means comprises: a delay line connected to said input means, said delay line having tapped outputs at predetermined delay increments; a plurality of selective band-pass filters one each connected to a tapped output of said delay and each filter having a pass band distinct from the pass band of the other filters of the plurality.
Claim 10
Dependent Claim
30 words
Apparatus in accordance with claim 7 wherein said plurality of filters is characterized in that all of the frequency bands are contiguous over the bandwidth of the magnetic recording apparatus.
Claim 11
Dependent Claim
58 words
Apparatus in accordance with claim 7 wherein said recording means comprises: a signal summation circuit connected in common to said plurality of filters for forming said composite signal; and a magnetic recording head positioned adjacent said magnetic storage medium and experiencing relative movement therewith to record the composite signal as a nonsaturating signal on a single information track.
Claim 12
Dependent Claim
62 words
Apparatus in accordance with claim 9 wherein the relative movement between the recording head and the magnetic storage medium is of randomly variable speeds; and wherein said delay means is variable by a factor related to said speed variations which establishes a constant spatial separation for each frequency band''s contribution to said composite analogue signal as recorded on said single information track.
Claim 13
Dependent Claim
86 words
Apparatus in accordance with claim 10 wherein said delay comprises an intermediate magnetic data storage device coupled to said input means through a second magnetic recording head, anD wherein said tapped outputs of said delay comprises a plurality of magnetic reproduce heads spaced apart at equal intervals and operatively coupled to said intermediate storage device to reproduce input data recorded thereon by said second recording head at equal time delay intervals for a constant relative speed between the storage device and said plurality of reproduce heads.
Claim 14
Dependent Claim
15 words
Apparatus in accordance with claim 11 wherein said intermediate magnetic storage device comprises a drum.
Claim 15
Dependent Claim
15 words
Apparatus in accordance with claim 11 wherein said intermediate magnetic storage device comprises a disc.
Claim 16
Dependent Claim
81 words
Apparatus in accordance with claim 11 wherein said intermediate magnetic storage device is rotatable past said plurality of reproduce heads; and said magnetic storage medium comprises a magnetic tape; said apparatus further comprising: a driving means for driving said tape past said first-claimed magnetic recording head at a speed which is randomly variable; and means operatively coupling said driving means to said intermediate magnetic storage device for varying its rotatable speed synchronously with said variable driving speeds for said magnetic tape.
Claim 17
Dependent Claim
27 words
Apparatus in accordance with claim 14 wherein the variations in rotational speed of said intermediate magnetic storage device result in inverse variations in said time delay intervals.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-03-08 | 1974-09-07 | 1975-03-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-03-08 | 1978-09-07 | 1979-03-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-03-08 | 1982-09-07 | 1983-03-09 | $7700.00 | Window Closed / Lapsed |