US3789377A
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Pseudo-random sequence synchronization for magnetic recording system
Assignee: Lockheed Electronics Co Inc
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Filing: 1972-05-26
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Granted: 1974-01-29
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Expires: 1992-05-26
Abstract
Abstract A synchronization technique for multiple channel magnetic recording systems, is disclosed. The synchronization technique involves the phase modulation of data to be recorded on each of several parallel recording channels in accordance with a repeated pseudo-random sequence. Upon recovery of recorded signals in the respective channels, the phase modulation is detected to reconstruct the pseudo-random sequence which is then autocorrelated to produce a synchronization pulse once each cycle of the pseudo-random sequence. The synchronization pulses may be employed to overcome the effects of tape skew, jitter, or the like.
Inventors
- 👤 K Norris
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 18:42
CPC Classifications
G; G11; G11B; G11B20/00; G11B20/10; G11B20/14; G11B20/1403; G11B20/1407; G11B20/1419
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
118 words
A synchronization system for providing pulsed synchronization signals at predetermined time intervals, said synchronization system being useful with magnetic recording systems adapted for concurrently recording digital data on multiple parallel channels, said recording system including recording circuitry having means for concurrently applying digital data to a recording transducer for recordation on a multiple channel recording medium, and recovery circuitry having means for recovering data signals recorded on said recording medium, said synchronization system comprising: generator means for providing a pseudo-random sequence signal including repetitive cycles of a selected succession of binary bits; and modulation means responsive to said pseudo-random sequence for phase modulating digital data signals to be recorded in accordance with said preselected succession of binary bits.
Claim 2
Dependent Claim
118 words
A synchronization system for providing pulsed synchronization signals at predetermined time intervals, said synchronization system being useful with magnetic recording systems adapted for concurrently recording digital data on multiple parallel channels, said recording system including recording circuitry having means for concurrently applying digital data to a recording transducer for recordation on a multiple channel recording medium, and recovery circuitry having means for recovering data signals recorded on said recording medium, said synchronization system comprising: generator means for providing a pseudo-random sequence signal including repetitive cycles of a selected succession of binary bits; and modulation means responsive to said pseudo-random sequence for phase modulating digital data signals to be recorded in accordance with said preselected succession of binary bits.
Claim 3
Dependent Claim
53 words
The synchronization system defined by claim 1 further including first complemEnting means for inverting alternate repetitive cycles of said pseudo-random sequence to have said digital data signals alternately phase modulated in accordance with said preselected succession of binary bits of said pseudo-random sequence, and the complement of said preselected succession of binary bits.
Claim 4
Dependent Claim
56 words
The synchronization system defined by claim 1 further including: regenerating means, responsive to recovered recorded signals, for regenerating the preselected succession of binary bits of said pseudo-random sequence signal, or the complement thereof; and auto-correlation means for auto-correlating said regnerated pseudo-random sequence signal to provide pulsed signals uniformly occurring once each cycle of said pseudo-random sequence.
Claim 5
Dependent Claim
64 words
The synchronization system defined by claim 3, said regenerating means including: detector means, connected to receive recovered recorded signals, for detecting the succession of binary bits, alternately forming said pseudo-random sequence and the complement thereof, used to phase modulate the recorded signals; and second complementing means for inverting alternate cycles of the detected succession of bits forming said pseudo-random sequence and the complement thereof.
Claim 6
Dependent Claim
27 words
The synchronization system defined by claim 3, further including detector means connected to said auto-correlator means for detecting said pulsed signals for providing desired pulsed synchronization signals.
Claim 7
Dependent Claim
61 words
The synchronization system defined by claim 1, said digital data signals to be recorded having a format including bit cells and for which a transition occurs at each bit cell boundary, said modulation means including means for respectively advancing and delaying the occurrence of said bit cell boundary transitions in response to binary ones and binary zeros of said pseudo-random sequence.
Claim 8
Dependent Claim
123 words
The synchronization system defined by claim 6, said modulation means including: a tapped delay line to which data signals to be recorded are applied, said tapped delay line including a plurality of output taps from which said data signals may be outputted from said delay line; an up/down counter, connected to receive said succession of bits forming said pseudo-random sequence and the complement thereof, for phase modulating said data signals to be recorded, the contents of said counter being respectively incremented or decremented in accordance with said binary ones and binary zeros of said succession of bits; and a data selector, responsive to operation of said up/down counter, for changing the output tap of said delay line from which data signals are outputted.
Claim 9
Dependent Claim
56 words
The synchronization system defined by claim 2 further including: regenerating means, responsive to recovered recorded signals, for regenerating the preselected succession of binary bits of said pseudo-random sequence signal, or the complement thereof; and auto-correlation means for auto-correlating said regenerated pseudo-random sequence signal to provide pulsed signals uniformly occurring once each cycle of said pseudo-random sequence.
Claim 10
Dependent Claim
65 words
The synchronization system defined by claim 8, said regenerating means including: detector means, connected to receive recovered recorded signals, for detecting said succession of binary bits alternately forming said pseudo-random sequence and the complement thereof, used to phase modulate the recorded data signals; and second complementing means for inverting alternate cycles of the detected succession of bits forming said pseudo-random sequence and the complement thereof.
Claim 11
Dependent Claim
78 words
The synchronization system defined by claim 9, said first and second complementing means including: an input connection; an output connection; a first selectively enabled conductive path for transmitting signals from said input connection to said output connection; a second selectively enabled conductive path for transmitting to said output connection an inversion of signals applied to said input coNnection; and control means for alternately enabling said first and second selectively conductive paths for alternate cycles of said pseudo-random sequence.
Claim 12
Dependent Claim
61 words
The synchronization system defined by claim 10, said digital data signals to be recorded having a format including bit cells and for which a transition occurs at each bit cell boundary, said modulation means including means for respectively advancing and delaying the occurrence of said bit cell boundary transitions in response to binary ones and binary zeros of said pseudo-random sequence.
Claim 13
Dependent Claim
123 words
The synchronization system defined by claim 11, said modulation means including: a tapped delay line to which data signals to be recorded are applied, said tapped delay line including a plurality of output taps from which said data signals may be outputted from said delay line; an up/down counter, connected to receive said succession of bits forming said pseudo-random sequence and the complement thereof, for phase modulating said data signals to be recorded, the contents of said counter being respectively incremented or decremented in accordance with said binary ones and binary zeros of said succession of bits; and a data selector, responsive to operation of said up/down counter, for changing the output tap of said delay line from which data signals are outputted.
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) | 1977-01-28 | 1977-07-30 | 1978-01-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-01-28 | 1981-07-30 | 1982-01-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-01-28 | 1985-07-30 | 1986-01-29 | $7700.00 | Window Closed / Lapsed |