US3798557A
Expired / Lapsed
US
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Interpolation of sinusoidal signals
Assignee: Applied Biosystems Inc
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Filing: 1972-03-31
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Granted: 1974-03-19
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Expires: 1992-03-31
Abstract
Abstract An interpolating system particularly adapted to obtain finer resolution in the readout of a pair of sinusoidal signals in quadrature, utilizing zero-crossing detecting techniques. The system retains the information as to which of the two signals leads the other. In the specific embodiment twelve evenly spaced, resolved elements (in the form of logic signals) are produced for each original full cycle of the signals, while retaining the advantage of the zero-crossing detection technique, e.g., insensitivity to (simultaneous) amplitude changes in both quadrature signals. The system preferably operates on a pair of pure A. C. sinusoidal waves (i.e., free of any D.C. component) each having equal (even if simultaneously varying) amplitude, but can be used on any pair of signals from which such equal amplitude pure sine waves in quadrature can be extracted. One field of use is in processing signals from distance-measuring interferometers, so as to obtain a more finely resolved distance measurement of the object being monitored (e.g., in units of 1/24 of the wavelength of radiation, where a whole cycle of the sinusoidal signals corresponds to 1/2 of a wavelength).
Inventors
- 👤 L Scott
- 👤 G Roth
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 19:14
CPC Classifications
G; G01; G01B; G01B9/00; G01B9/02; G01B9/02083; G01R; G01R25/00; H; H03; H03M; H03M1/00; H03M1/12; H03M1/22; H03M1/24; H03M1/28; H03M1/30
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
235 words
Apparatus for obtaining signals indicating equal length portions of each cycle of a pair of sinusoidal components of equal period and fixed phase relationship contained in an A.C. electrical waveform, so as to yield more finely resolved interpolated interval elements for each such cycle, comprising: means for producing and albegraically adding analog functions of said pair of sinusoidal components so as to obtain first derived analog signals which are similar in form to said sinusoidal components but are shifted in phase by equal incremental amounts relative to one of said sinusoidal components, so as to cross zero at more than two equally spaced points relative to the cycle of said one sinusoidal component; the zero crossings of said first derived analog signals forming an ordered sequence of equally spaced points for each cycle of said one of said pair of sinusoidal components with the particular sequence of crossings being determined by the relative phase relationship of said pair of components; means for sequentially determining each such zero crossing of said first derived signals and for producing an ordered set of interval signals, each corresponding to adjacent zero crossings of said derived signals, whereby each of said interval signals discretely indicates an equal length portion of a cycle of one of the original sinusoidal components, the particular ordered nature of said set of interval signals indicating the relative phase relationship between the pair of original components.
Claim 2
Dependent Claim
235 words
Apparatus for obtaining signals indicating equal length portions of each cycle of a pair of sinusoidal components of equal period and fixed phase relationship contained in an A.C. electrical waveform, so as to yield more finely resolved interpolated interval elements for each such cycle, comprising: means for producing and albegraically adding analog functions of said pair of sinusoidal components so as to obtain first derived analog signals which are similar in form to said sinusoidal components but are shifted in phase by equal incremental amounts relative to one of said sinusoidal components, so as to cross zero at more than two equally spaced points relative to the cycle of said one sinusoidal component; the zero crossings of said first derived analog signals forming an ordered sequence of equally spaced points for each cycle of said one of said pair of sinusoidal components with the particular sequence of crossings being determined by the relative phase relationship of said pair of components; means for sequentially determining each such zero crossing of said first derived signals and for producing an ordered set of interval signals, each corresponding to adjacent zero crossings of said derived signals, whereby each of said interval signals discretely indicates an equal length portion of a cycle of one of the original sinusoidal components, the particular ordered nature of said set of interval signals indicating the relative phase relationship between the pair of original components.
Claim 3
Dependent Claim
38 words
Apparatus according to claim 1, in which: said original pair of sinusoidal components are in phase quadrature and said producing and algebraically adding means comprises means for producing and adding linear functions of said pair of sinusoidal components.
Claim 4
Dependent Claim
105 words
Apparatus according to claim 2, in which: said original pair of sinusoidal components are pure sine waves free of any D. C. components and are therefore symmetrical about zero; and said linear functions thereof are directly proportional to said pure sine wave sinusoidal components and therefore are also free of any D. C. components, whereby said first derived analog signals are also pure sine waves, symmetrical about zero and free of any D. C. components, so that the zero crossing points of both the original sinusoidal components and also said first derived analog signals are invariable for equal amplitude changes in said original sinusoidal components.
Claim 5
Dependent Claim
55 words
Apparatus according to claim 1, further comprising: means for receiving said interval signals, for determining the particular order of said interval signals, and for producing in accordance therewith a direction signal indicating said particular order, whereby a directional signal, ultimately determined by the relative phase relationship between the pair of original sinusoidal components, is obtained.
Claim 6
Dependent Claim
126 words
Apparatus according to claim 4, in which: said receiving and determining means comprises means for determining upon the occurrence of each interval signal whether it was immediately preceded by that particular one interval signal which occurs immediately before it for a particular first order of said interval signals corresponding to a particular first phase relationship between said pair of original sinusoidal components, or whether it was preceded by that particular other interval signal which occurs immediately before it for a particular second order of said interval signals corresponding to a particular second phase relationship between said pair of original sinusoidal components, whereby the direction signal is produced upon the occurrence of each and every interval signal, so that ambiguity for even a single interval is avoided.
Claim 7
Dependent Claim
44 words
Apparatus according to claim 1, further comprising: means for receiving said interval signals and for generating a discrete, countable pulse for each said interval signal, whereby each equal length portion of a cycle of one of the original sinusoidal components may be readily counted.
Claim 8
Dependent Claim
67 words
Apparatus according to claim 6, further comprising: means for receiving and for determining the particular order of said interval signals, and for producing in accordance therewith a direction signal indicating said particular order, whereby a directional signal, ultimately determined by the relative phase relationship between the pair of original sinusoidal components is obtained, so that each discrete countable pulse may be alGebraically counted in the appropriate sense.
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) | 1977-03-18 | 1977-09-17 | 1978-03-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-03-18 | 1981-09-17 | 1982-03-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-03-18 | 1985-09-17 | 1986-03-19 | $7700.00 | Window Closed / Lapsed |