US4017803A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Data recovery system resistant to frequency deviations
Assignee: Unisys Corp
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Filing: 1976-01-29
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Granted: 1977-04-12
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Expires: 1996-01-29
Abstract
Abstract The data stream input to the recovery logic is taken from a point at which its transitions are timecoincident with those of the data stream input to the phase comparator of the phase locked oscillator loop used to control the generation of the recovery windows. No delay is provided between the data stream take-off point and its input to the recovery logic. The PLO and the window generating circuits cooperate to maintain data and clock representative transitions in the data stream applied to the recovery logic centered in the respective windows.
Inventors
- 👤 Kenneth L. Baker
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 13:41
CPC Classifications
H; H03; H03L; H03L7/00; H03L7/06; H03L7/08; H03L7/0807; G; G11; G11B; G11B20/00; G11B20/10; G11B20/14; G11B20/1403; G11B20/1423; H04; H04L; H04L25/00; H04L25/38; H04L25/40; H04L25/49; H04L25/4904
Claims Analysis
Total Claims: 26
Claim 1
Independent Claim
164 words
In a system for recovering encoded binary information which is represented in a data stream at time positions recurring at a frequency that is nominally predetermined but subject to uncontrollable deviations, the system including means for generating signals having alternating high and low portions for use as recovery windows, recovery logic supplied with said windows, and a phase locked oscillator loop controlled by a phase comparator and determining the times of occurrence of the windows, the phase comparator having supplied to it two comparison signals, one being the feedback signal within the loop and the other being a signal derived from the data stream, the improvement which comprises means for supplying to the recovery logic a signal also derived from the data stream and having information representative time-varying characteristics which occur substantially concurrently with corresponding time-varying characteristics of the said signal derived from the data stream which is supplied to the phase comparator, and which do so occur substantially independently of said frequency deviations.
Claim 2
Dependent Claim
164 words
In a system for recovering encoded binary information which is represented in a data stream at time positions recurring at a frequency that is nominally predetermined but subject to uncontrollable deviations, the system including means for generating signals having alternating high and low portions for use as recovery windows, recovery logic supplied with said windows, and a phase locked oscillator loop controlled by a phase comparator and determining the times of occurrence of the windows, the phase comparator having supplied to it two comparison signals, one being the feedback signal within the loop and the other being a signal derived from the data stream, the improvement which comprises means for supplying to the recovery logic a signal also derived from the data stream and having information representative time-varying characteristics which occur substantially concurrently with corresponding time-varying characteristics of the said signal derived from the data stream which is supplied to the phase comparator, and which do so occur substantially independently of said frequency deviations.
Claim 3
Dependent Claim
52 words
The system of claim 1 comprising the further improvement that the recovery window generating means and the phase locked oscillator are constructed so that the same time-varying characteristics in the signal supplied to the recovery logic from the data stream are substantially centered within recovery windows, substantially independently of said frequency deviations.
Claim 4
Dependent Claim
35 words
The system of claim 2 wherein the means for supplying the signal derived from the data stream to the recovery logic includes signal processing means for producing stretched replicas of pulses in the data stream.
Claim 5
Dependent Claim
37 words
The system of claim 3 wherein the means for supplying the comparison signal derived from the data stream to the phase comparator also includes signal processing means for producing stretched replicas of pulses in the data stream.
Claim 6
Dependent Claim
18 words
The system of claim 4 wherein the signal processing means stretches both replicas by substantially the same amounts.
Claim 7
Dependent Claim
18 words
The system of claim 5 wherein the signal processing means is a single-shot multivibrator producing both stretched replicas.
Claim 8
Dependent Claim
21 words
The system of claim 6 wherein the stretched replicas are produced at the Q and Q outputs of the multivibrator, respectively.
Claim 9
Dependent Claim
24 words
The system of claim 5 wherein the output signals of the pulse stretching means are supplied to the recovery logic without intervening delay means.
Claim 10
Dependent Claim
30 words
The system of claim 8 wherein the phase locked oscillator loop comprises a voltage controlled oscillator operating at a harmonic of the recurrence frequency of the information representative time positions.
Claim 11
Dependent Claim
48 words
The system of claim 9 wherein the window producing means includes a counter supplied with the output from the harmonic oscillator and responsive thereto to produce corresponding counts, recurring at a periodicity equal to that of the recurrence period of the information time positions in the data stream.
Claim 12
Dependent Claim
34 words
The system of claim 10, wherein the counter means includes means for producing an output signal having within each recurrence period a high and a low portion, respectively coinciding with predetermined series of counts.
Claim 13
Dependent Claim
26 words
The system of claim 11, comprising means for supplying the said high and low counter output signal portions to the recovery logic as the recovery windows.
Claim 14
Dependent Claim
34 words
The system of claim 12, wherein the recovery logic includes means for utilizing the recovery windows and the output signals of the pulse stretching means to recover the information encoded in said output signals.
Claim 15
Dependent Claim
39 words
The system of claim 13, wherein the recovery logic includes means for utilizing one window in each recurrence period to recover the ones and zeros encoded in the output signals, and the other window to recover the encoded clock.
Claim 16
Dependent Claim
40 words
The system of claim 14, wherein the recovery logic includes two signal paths, each supplied with the pulse stretching means output signals and the recovery windows, and respectively supplied with signals representing the centers of one and the other window.
Claim 17
Dependent Claim
22 words
The system of claim 12, wherein the counter means is constructed to produce the high and low signal portions with unequal durations.
Claim 18
Dependent Claim
29 words
The system of claim 11, wherein the data stream is M 2 FM encoded and the durations of the high and low signal portions are in a 40/60 ratio.
Claim 19
Dependent Claim
24 words
The system of claim 16, wherein the phase locked oscillator loop comprises feedback logic supplied with the output signal from the voltage controlled oscillator.
Claim 20
Dependent Claim
49 words
The system of claim 18, comprising means for deriving first and second auxiliary signals from the counter means, the first auxiliary signal having transitions phase shifted from those of the recovery windows by a predetermined amount, the second having transitions coinciding with the centers of the respective recovery windows.
Claim 21
Dependent Claim
27 words
The system of claim 19, wherein the data stream is M 2 FM encoded, and the transitions in the first auxiliary signal are phase shifted by 180°.
Claim 22
Dependent Claim
38 words
The system of claim 19, comprising means for applying the first auxiliary signal to the feedback logic to clock a signal derived from that comparison signal supplied to the phase comparator which is derived from the data stream.
Claim 23
Dependent Claim
43 words
The system of claim 21, wherein the feedback logic includes a flip-flop to which the first auxiliary signal is applied as the clock and which is reset by the same signal which is supplied to the phase comparator as its feedback comparison signal.
Claim 24
Dependent Claim
27 words
The system of claim 21, comprising means for applying the second auxiliary signal to the feedback logic to gate the signal clocked by the first auxiliary signal.
Claim 25
Dependent Claim
53 words
The system of claim 23, wherein the feedback logic includes a NAND gate to which the signal clocked by the first auxiliary signal and the second auxiliary signal are both applied, and a flip-flop supplied with the output sugnal from the NAND gate, and with the voltage controlled oscillator output as the clock.
Claim 26
Dependent Claim
31 words
The system of claim 24 wherein the output signal of the last-named flip-flop constitutes the feedback logic output signal and is supplied to the phase comparator as its feedback comparison signal.
References Cited (Backward Citations)
US3825844A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-04-11 | 1980-10-11 | 1981-04-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-04-11 | 1984-10-11 | 1985-04-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-04-11 | 1988-10-11 | 1989-04-12 | $7700.00 | Window Closed / Lapsed |