US4001884A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus and method for recording and reproducing digital-data
Assignee: AT&T Teletype Corp
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Filing: 1975-07-10
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Granted: 1977-01-04
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Expires: 1995-07-10
Abstract
Abstract A series of digital words are demultiplexed into two groups and recorded on parallel tracks of a magnetic tape. The digital information is phase encoded upon the two tape channels and during playback the magnetic flux reversals on each channel are separately detected. The peak level of the detected signal is sensed and a peak signal pulse generated corresponding to the occurrence of the peak of the detected signal. Means are additionally included for setting the minimum threshold of the incoming signal necessary to generate a signal pulse so as to provide a level of immunity to system noise. The peak signal pulses are decoded to reconstruct the original data signal and a clocking signal. The data from each of the channel decoders is clocked into respective channel shift registers and multiplexed into its original data word arrangement.
Inventors
- 👤 Wayne R. Herbst
- 👤 Paul L. Mika
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 13:03
CPC Classifications
G; G11; G11B; G11B20/00; G11B20/10; G11B20/14; G11B20/1403; G11B20/1407; G11B20/1419; G11B20/10009; G11B20/12; G11B20/1201; G11B20/1202; G11B20/1423; G11B20/1426; G11B20/16
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
165 words
An apparatus for detecting digital signals played back from a magnetic tape whereon said signal information is recorded in the form of magnetic flux reversals, said flux reversals, during playback, producing a varying signal having a peak amplitude, the improvement comprising: means for amplifying said varying signal, said amplifying means having a first input receiving said varying signal and a second input, said second input providing an amplified output inverted with respect to the amplified output created by said first input; and means, responsive to a predetermined level of the output signal, for coupling said output signal to said second input and storage means coupled to said second input whereby said output signal follows said varying signal at said first input until said coupling means conducts thereby maintaining said output signal constant and in response to a slope reversal of said varying signal, the input signals to said amplifier become additive producing an abrupt reversal in the polarity of said output voltage from said amplifier.
Claim 2
Independent Claim
165 words
An apparatus for detecting digital signals played back from a magnetic tape whereon said signal information is recorded in the form of magnetic flux reversals, said flux reversals, during playback, producing a varying signal having a peak amplitude, the improvement comprising: means for amplifying said varying signal, said amplifying means having a first input receiving said varying signal and a second input, said second input providing an amplified output inverted with respect to the amplified output created by said first input; and means, responsive to a predetermined level of the output signal, for coupling said output signal to said second input and storage means coupled to said second input whereby said output signal follows said varying signal at said first input until said coupling means conducts thereby maintaining said output signal constant and in response to a slope reversal of said varying signal, the input signals to said amplifier become additive producing an abrupt reversal in the polarity of said output voltage from said amplifier.
Claim 3
Dependent Claim
67 words
The apparatus of claim 1 wherein said coupling means comprises a pair of diode junctions, said diode junctions being parallel connected and reversed biased so as to couple the output voltage from said amplifier to the second input thereof when the output exceeds a predetermined value and said storage means comprises a capacitor connected between said second amplifier input and the common supply terminal to said amplifier.
Claim 4
Dependent Claim
56 words
The apparatus of claim 1 which further comprises a decoder and means for coupling said amplifier to said decoder, means for interrupting the output of said amplifier to said decoder below a fixed level thereby establishing a minimum threshold below which the peak amplitude output of said amplifier is prevented from being coupled to said decoder.
Claim 5
Dependent Claim
88 words
The apparatus of claim 3 wherein said threshold interrupting means comprises an amplifier, a negative peak interrupting circuit responsive to the negative peak output of said second amplifier and serving to interrupt the output of said first amplifier when the negative amplifier output fails to exceed a predetermined negative threshold level and a positive peak interrupting circuit responsive to the output of said second amplifier and serving to interrupt the output of said first amplifier when the positive amplifier output fails to exceed a predetermined positive threshold level.
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) | 1980-01-04 | 1980-07-05 | 1981-01-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-01-04 | 1984-07-05 | 1985-01-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-01-04 | 1988-07-05 | 1989-01-04 | $7700.00 | Window Closed / Lapsed |