US3812531A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Verifying status while initializing readback channels in a multichannel magnetic record readback system
Assignee: International Business Machines Corp
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Filing: 1972-12-26
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Granted: 1974-05-21
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Expires: 1992-12-26
Abstract
Abstract In starting to read a digital magnetic record of the multichannel self-clocking type, comparison circuits monitor deskewing apparatus for determining whether or not any of the channels have had an early start or no start of operation. After any channel has processed a predetermined number of bits within a data field and no deskewed data has been transferred, a test skew operation determines whether one or a small number of channels is in a marginal or almost-excessive skew condition with respect to all of the other channels. If such is the case, that small number of channels is deadtracked for enabling the readback system to read the record and transfer signals while deadtracking such few channels. The system is preferably employed with so-called ''''onthe-fly'''' error corrections.
Inventors
- 👤 P Hall
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 19:54
CPC Classifications
G; G11; G11B; G11B20/00; G11B20/20
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
391 words
An improved magnetic recording/readback system operable with a multitrack magnetic member; a plurality of channels respectively associated with tracks in said multitrack media, each channel including independent selfclocking readback and detection means for supplying data signals recovered from the respective tracks in asynchronous relationship to each and every other channel; first means in each of said channels for indicating start of readback signals; deskewing means receiving signals from each said channel and having a given number of deskewing positions, independent means in said deskewing means operatively associated with each of the respective channels for receiving signals therefrom and indicating relative positions thereof in said deskewing means with respect to other received signals from other tracks, and common means in said deskewing means responsive to said independent means for supplying aligned output signals from all of said channels; first monitor means associated with said independent and common means for detecting the difference between any one of said independent means and said common means which exceeds the deskewing capacity of said deskewing means by indicating a difference having a predetermined relationship to said given number for indicating an excessive skew condition; the improvement including in combination: stepping means in each said independent means responsive to said start of data signal to step said independent means in accordance with bit periods established bY the respective selfclocking means; test initiating means responsive to any of said stepping means having stepped a predetermined number of bit periods after said start of data to supply a test skew signal; comparison means responsive to any one of said test skew signals for comparing all of said independent means and said common means for indicating the respective deskewing condition of said deskewing means for determining that a given number of said independent means has a leading or lagging condition in said deskewing means with respect to a number of said independent means less than said given number; means responsive to said comparison means to inhibit transfer of signals from any of said desired ones of said plural channels for transferring signals to said deskewing means, and further operative to inhibit said independent means from actuating said common means to supply output signals from said deskewing means independent of said detected ones channels; and control means responsive to said common means being operated to inhibit operation of said comparison means.
Claim 2
Dependent Claim
391 words
An improved magnetic recording/readback system operable with a multitrack magnetic member; a plurality of channels respectively associated with tracks in said multitrack media, each channel including independent selfclocking readback and detection means for supplying data signals recovered from the respective tracks in asynchronous relationship to each and every other channel; first means in each of said channels for indicating start of readback signals; deskewing means receiving signals from each said channel and having a given number of deskewing positions, independent means in said deskewing means operatively associated with each of the respective channels for receiving signals therefrom and indicating relative positions thereof in said deskewing means with respect to other received signals from other tracks, and common means in said deskewing means responsive to said independent means for supplying aligned output signals from all of said channels; first monitor means associated with said independent and common means for detecting the difference between any one of said independent means and said common means which exceeds the deskewing capacity of said deskewing means by indicating a difference having a predetermined relationship to said given number for indicating an excessive skew condition; the improvement including in combination: stepping means in each said independent means responsive to said start of data signal to step said independent means in accordance with bit periods established bY the respective selfclocking means; test initiating means responsive to any of said stepping means having stepped a predetermined number of bit periods after said start of data to supply a test skew signal; comparison means responsive to any one of said test skew signals for comparing all of said independent means and said common means for indicating the respective deskewing condition of said deskewing means for determining that a given number of said independent means has a leading or lagging condition in said deskewing means with respect to a number of said independent means less than said given number; means responsive to said comparison means to inhibit transfer of signals from any of said desired ones of said plural channels for transferring signals to said deskewing means, and further operative to inhibit said independent means from actuating said common means to supply output signals from said deskewing means independent of said detected ones channels; and control means responsive to said common means being operated to inhibit operation of said comparison means.
Claim 3
Dependent Claim
60 words
The system set forth in claim 1 further including means responsive to said first means to indicate beginning of record (BOR) when a preset number of said first means indicates beginning of readback signals, the improvement further including in combination: means selectively inhibiting each said stepping means and means responsive to said BOR indication to initiate all said stepping means.
Claim 4
Dependent Claim
197 words
A start read and record circuit for a digital signal magnetic recorder adapted to operate with a multitrack record media having signal preambles in each track preceding recorded data signals; means detecting and indicating beginning of record in a predetermined number of said tracks, means associated with each record track detecting and indicating beginning of data signals following the respective preamble signals, means associated with each track counting data signals recovered from each track, respectively; deskew means indicating readback from all said record tracks; the improved start read circuit including in combination: first means detecting that a given number of data signals has been transferred from any one of said record tracks; second means responsive to said first means for comparing the number of signals read from all said record tracks, and indicating whether or not a predetermined difference exists between said number of signals; third means responsive to said predetermined difference to indicate a possible error condition; deadtrack means jointly responsive to said indicated possible error condition and said counts to selectively inhibit transfer of signals from a selected record track; and fourth means responsive to said deskew means to inhibit operation of said third means.
Claim 5
Dependent Claim
197 words
A start read and record circuit for a digital signal magnetic recorder adapted to operate with a multitrack record media having signal preambles in each track preceding recorded data signals; means detecting and indicating beginning of record in a predetermined number of said tracks, means associated with each record track detecting and indicating beginning of data signals following the respective preamble signals, means associated with each track counting data signals recovered from each track, respectively; deskew means indicating readback from all said record tracks; the improved start read circuit including in combination: first means detecting that a given number of data signals has been transferred from any one of said record tracks; second means responsive to said first means for comparing the number of signals read from all said record tracks, and indicating whether or not a predetermined difference exists between said number of signals; third means responsive to said predetermined difference to indicate a possible error condition; deadtrack means jointly responsive to said indicated possible error condition and said counts to selectively inhibit transfer of signals from a selected record track; and fourth means responsive to said deskew means to inhibit operation of said third means.
Claim 6
Dependent Claim
55 words
The start read circuit set forth in claim 3 wherein said deadtrack means includes voting means indicating whether a given majority of said readback signals leads or lags the remaining ones of said readback signals by a given number of signals and means in said deadtrack means deadtracking said tracks yielding said remaining readback signals.
Claim 7
Dependent Claim
99 words
The start read circuit set forth in claim 3 further including pointer signal means selectively supplying pointer signals indicating a possible signal error condition in signals from any of said record tracks; marginal skew means responsive to said counting means to indicate count differences representing almost-excessive skew between readback signals; voting means indicating whether a given majority of said readback signals leads or lags remaining ones of said readback signals; and deadtrack indicating means in said deadtrack means jointly responsive to said pointer signals, said marginal skew means, and said voting means to selectively deadtrack signals from selected tracks.
Claim 8
Dependent Claim
43 words
The start read circuit set forth in claim 5 wherein said deadtrack initiating means includes means jOintly responsive to said deskew means, said pointer signals, and said marginal skew means to indicate dead-tracking for those record tracks respectively associated with said pointer signals.
Claim 9
Dependent Claim
50 words
The start read circuit set forth in claim 5 including means indicating a given skew condition for each said readback signal; and said deadtrack initiating means including means receiving said given skew indications for any of said tracks as pointer signals whenever said voting means indicates most tracks are leading.
Claim 10
Independent Claim
160 words
The method of initiating the readback of signals from a multitrack record member having aligned synchronization portions and data signal portions in each track, the improved method including the steps of: simultaneously sensing synchronization portion signals from all tracks and attempting to independently synchronize readback circuit operation thereto for each of said tracks; independently for each track attempting to determine beginning of each said data signal portion and indicating such status, comparing the status indications for all said tracks for said beginning of data portions; detecting which of said indications represent a time of detection of a beginning of data portion within a preset time range and which of said indications represent a time of detection of a beginning of data portion with a predetermined time difference from said preset time range; and deadtracking those readback circuits for tracks having a beginning of data determination status indication with said predetermined time difference relationship to other ones of said status indications.
Claim 11
Independent Claim
160 words
The method of initiating the readback of signals from a multitrack record member having aligned synchronization portions and data signal portions in each track, the improved method including the steps of: simultaneously sensing synchronization portion signals from all tracks and attempting to independently synchronize readback circuit operation thereto for each of said tracks; independently for each track attempting to determine beginning of each said data signal portion and indicating such status, comparing the status indications for all said tracks for said beginning of data portions; detecting which of said indications represent a time of detection of a beginning of data portion within a preset time range and which of said indications represent a time of detection of a beginning of data portion with a predetermined time difference from said preset time range; and deadtracking those readback circuits for tracks having a beginning of data determination status indication with said predetermined time difference relationship to other ones of said status indications.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-05-20 | 1977-11-19 | 1978-05-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-05-20 | 1981-11-19 | 1982-05-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-05-20 | 1985-11-19 | 1986-05-21 | $7700.00 | Window Closed / Lapsed |