Patent US3744913A successfully refreshed from Google Patents.
US3744913A
Expired / Lapsed
US
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Device for determining relative angular position between a spacecraft and a radiation emitting celestial body
Assignee: National Aeronautics and Space Administration
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Filing: 1972-02-24
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Granted: 1973-07-10
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Expires: 1992-02-24
Abstract
Abstract Signals indicative of the relative angular position between a spin stabilized spacecraft, probe, or sounding rocket and a radiation emitting celestial body are derived with a detector including four electrodes for deriving indications of the centroid the radiation image on the detector. During each spin of the satellite each electrode derives a signal having a first non-zero level while the detector is not illuminated by the radiation and a sound non-zero level while it is illuminated by the radiation. The first level is indicative of dark current, while the second level is dependent upon dark current, the angular position of the centroid of the image on the detector surface relative to the electrode, and the intensity of the radiation impinging on the detector. A processing network, including a negative feedback loop, responds to the signal to derive, during each spin of the spacecraft, a signal indicative of the dark current. The dark current indicating signal is combined, in the feedback loop, with the electrode output to derive an output signal having a substantially zero value while the dark current is being generated. The image of the body is formed on the detector surface with a pinhole.
Inventors
- 👤 W Farthing
- 👤 H Frisbie
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 12:40
CPC Classifications
G; G01; G01S; G01S3/00; G01S3/78; G01S3/782
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
227 words
A device for deriving signals indicative of the relative angular position of a radiation emitting celestial body and a spinning spacecraft comprising a detector for the radiation, means for forming a radiation image of the body on the detector, said image having an area much less than the detecting surface of the detector, said detector deriving a first signal having a first non-zero level while said detector is not illuminated by said radiation and a second non-zero level while it is illuminated by said radiation, said first level being subject to change in response to internal conditions of the detector, said second level being dependent upon: the internal conditions, the position of the centroid of said image on the detector surface, and the intensity of said radiation impinging on the detector; said first and second levels being derived in sequence during each spin of the spacecraft, means responsive during each spin to the first signal for deriving a second signal having a level proportional to the first level, said second signal remaining substantially constant throughout the interval of each spin, and means combining the first and second signals for deriving a third signal having a substantially zero level while the first level is being derived and a third level substantially proportional to the difference between the first and second levels while the second level is being derived.
Claim 2
Independent Claim
227 words
A device for deriving signals indicative of the relative angular position of a radiation emitting celestial body and a spinning spacecraft comprising a detector for the radiation, means for forming a radiation image of the body on the detector, said image having an area much less than the detecting surface of the detector, said detector deriving a first signal having a first non-zero level while said detector is not illuminated by said radiation and a second non-zero level while it is illuminated by said radiation, said first level being subject to change in response to internal conditions of the detector, said second level being dependent upon: the internal conditions, the position of the centroid of said image on the detector surface, and the intensity of said radiation impinging on the detector; said first and second levels being derived in sequence during each spin of the spacecraft, means responsive during each spin to the first signal for deriving a second signal having a level proportional to the first level, said second signal remaining substantially constant throughout the interval of each spin, and means combining the first and second signals for deriving a third signal having a substantially zero level while the first level is being derived and a third level substantially proportional to the difference between the first and second levels while the second level is being derived.
Claim 3
Dependent Claim
23 words
The device of claim 1 further including means for multiplying the third signal by a level indicative of the intensity of the source.
Claim 4
Dependent Claim
27 words
The device of claim 2 wherein the source is subject to intEnsity variations, and means for changing the multiplication level as a function of the intensity variations.
Claim 5
Dependent Claim
27 words
The device of claim 1 wherein said image forming means is a pinhole having an area no greater than approximately one-tenth the area of the detecting surface.
Claim 6
Independent Claim
315 words
A device for deriving signals indicative of the relative angular position of a radiation emitting celestial body and a spinning spacecraft comprising a detector for the radiation, means for forming a radiation image of the body on the detector, said image having an area much less than the detecting surface of the detector, said detector having a planar detecting surface with substantial lengths in two directions at right angles to each other, said detector including a plurality of output electrodes, said plurality being greater than two, said electrodes being spaced relative to said surface so that at each of them there is derived a signal having a first non-zero level while said detector is not illuminated by said radiation and a second non-zero level while it is illuminated by said radiation, said first level being subject to change in response to internal conditions of the detector, said second level being dependent upon: the internal conditions, the position of the centroid of said image on the detector surface relative to the electrode, and the intensity of said radiation impinging on the detector; the relative amplitudes of the second levels derived from the plural electrodes providing an indication of the position of the detector and image in two directions at right angles to each other, said first and second levels being derived in sequence during each spin of the spacecraft, means, for each electrode, responsive during each spin to the first signal for deriving a second signal having a level proportional to the first level, said second signal remaining substantially constant throughout the interval of each spin, and means, for each electrode, combining the first and second signals for deriving a third signal having a substantially zero level while the first level is being derived and a third level substantially proportional to the difference between the first and second levels while the second level is being derived.
Claim 7
Independent Claim
315 words
A device for deriving signals indicative of the relative angular position of a radiation emitting celestial body and a spinning spacecraft comprising a detector for the radiation, means for forming a radiation image of the body on the detector, said image having an area much less than the detecting surface of the detector, said detector having a planar detecting surface with substantial lengths in two directions at right angles to each other, said detector including a plurality of output electrodes, said plurality being greater than two, said electrodes being spaced relative to said surface so that at each of them there is derived a signal having a first non-zero level while said detector is not illuminated by said radiation and a second non-zero level while it is illuminated by said radiation, said first level being subject to change in response to internal conditions of the detector, said second level being dependent upon: the internal conditions, the position of the centroid of said image on the detector surface relative to the electrode, and the intensity of said radiation impinging on the detector; the relative amplitudes of the second levels derived from the plural electrodes providing an indication of the position of the detector and image in two directions at right angles to each other, said first and second levels being derived in sequence during each spin of the spacecraft, means, for each electrode, responsive during each spin to the first signal for deriving a second signal having a level proportional to the first level, said second signal remaining substantially constant throughout the interval of each spin, and means, for each electrode, combining the first and second signals for deriving a third signal having a substantially zero level while the first level is being derived and a third level substantially proportional to the difference between the first and second levels while the second level is being derived.
Claim 8
Dependent Claim
44 words
The device of claim 5 wherein the second signal deriving means for each electrode includes: signal storage means normally responsive to said first signal, and means responsive to the detector being illuminated by the source for decoupling the first signal from the storage means.
Claim 9
Dependent Claim
117 words
The device of claim 5 wherein each of the signals is d.c., and the second and third signal deriving means for each electrode includes: a feedback network having an input responsive to the first signal, means responsive to the first and second signals for deriving a d.c. difference signal, means for amplifying the difference signal to derive the third signal, a storage capacitor for deriving the second signal, switch means for normally feeding the third signal to the storage capacitor, and means responsive to the detector being illuminated by the source for activating the switch means to prevent the third signal from being fed to the storage capacitor while the detector is being illuminated by the body.
Claim 10
Dependent Claim
21 words
The device of claim 7 wherein the means for activating is responsive to the third signals for all of said electrodes.
Claim 11
Dependent Claim
33 words
The device of claim 5 further including means for periodically sampling, at a frequency much greater than the spin frequency, the third signal for all of said electrodes at substantially the same time.
Claim 12
Dependent Claim
60 words
The device of claim 9 further including means for separately storing the sampled signal for each electrode, means for time multiplexing the stored sampled signals, and a single variable gain output channel responsive to the time multiplexing means, said output channel including means for multiplying each of the third signals by a level indicative of the intensity of the source.
Claim 13
Dependent Claim
27 words
The device of claim 10 wherein the source is subject to intensity variations, And means for changing the multiplication level as a function of the intensity variations.
Claim 14
Dependent Claim
51 words
The device of claim 11 wherein said output channel introduces an offset so that it derives a signal having a finite, non-zero value while none of the third signals is fed through the multiplexing means, and means responsive to the signal derived by the channel for removing the offset from it.
Claim 15
Dependent Claim
27 words
The device of claim 5 wherein said image forming means is a pinhole having an area no greater than approximately one-tenth the area of the detecting surface.
Claim 16
Independent Claim
247 words
A device for deriving signals indicative of the relative angular position of a radiation emitting celestial body and a spacecraft comprising a detector for the radiation, means for forming a radiation image of the body on the detector, said image having an area much less than the detecting surface of the detector, said detector deriving a first signal having a first non-zero level while said detector is not illuminated by said radiation and a second non-zero level while it is illuminated by said radiation, said first level being subject to change in response to internal conditions of the detector, said second level being dependent upon: the internal conditions, the position of the centroid of said image on the detector surface, and the intensity of said radiation impinging on the detector; said spacecraft including means for cyclically chopping the radiation illuminating the detector so that said first and second values are derived in sequence during each chopping cycle while the radiation is respectively blocked and passed by the chopping means, means responsive only to the first signal for deriving a second signal having a level proportional to the first level, said second signal remaining substantially constant throughout a complete chopping cycle, and means combining the first and second signals for deriving a third signal having a substantially zero level while the first level is being derived and a third level substantially proportional to the difference between the first and second levels while the second level is being derived.
Claim 17
Independent Claim
247 words
A device for deriving signals indicative of the relative angular position of a radiation emitting celestial body and a spacecraft comprising a detector for the radiation, means for forming a radiation image of the body on the detector, said image having an area much less than the detecting surface of the detector, said detector deriving a first signal having a first non-zero level while said detector is not illuminated by said radiation and a second non-zero level while it is illuminated by said radiation, said first level being subject to change in response to internal conditions of the detector, said second level being dependent upon: the internal conditions, the position of the centroid of said image on the detector surface, and the intensity of said radiation impinging on the detector; said spacecraft including means for cyclically chopping the radiation illuminating the detector so that said first and second values are derived in sequence during each chopping cycle while the radiation is respectively blocked and passed by the chopping means, means responsive only to the first signal for deriving a second signal having a level proportional to the first level, said second signal remaining substantially constant throughout a complete chopping cycle, and means combining the first and second signals for deriving a third signal having a substantially zero level while the first level is being derived and a third level substantially proportional to the difference between the first and second levels while the second level is being derived.
Claim 18
Independent Claim
331 words
A system for deriving signals indicative of the angular position of a radiation emitting celestial body and a spacecraft comprising a detector for the radiation, means for forming a radiation image of the body on the detector, said image having an area much less than the detecting surface of the detector, said detector having a planar detecting surface with substantial lengths in two directions at right angles to each other, said detector including a plurality of output electrodes, said plurality being greater than two, said electrodes being spaced relative to said surface so that at each of them there is derived a signal having a first non-zero level while said detector is not illuminated by said radiation and a second non-zero level while it is illuminated by said radiation, said first level being subject to change in response to internal conditions of the detector, said second level being dependent upon: the internal conditions, the position of the centroid of said image on the detector surface relative to the electrode, and the intensity of said radiation impinging on the detector; the relative amplitudes of the second levels derived from the plural electrodes providing an indication of the position of the detector and image in two directions at right angles to each other, said spacecraft including means for cyclically chopping the radiation illuminating the detector so that said first and second values are derived in sequence during each chopping cycle while the radiation is respectively blocked and passed by the chopping means, means responsive only to the first signal for deriving a second signal having a level proportional to the first level, said second signal remaining substantially constant throughout a complete chopping cycle, and means, for each electrode, combining the first and second signals for deriving a third signal having a substantially zero level while the firsT level is being derived and a third level substantially proportional to the difference between the first and second levels while the second level is being derived.
Claim 19
Independent Claim
331 words
A system for deriving signals indicative of the angular position of a radiation emitting celestial body and a spacecraft comprising a detector for the radiation, means for forming a radiation image of the body on the detector, said image having an area much less than the detecting surface of the detector, said detector having a planar detecting surface with substantial lengths in two directions at right angles to each other, said detector including a plurality of output electrodes, said plurality being greater than two, said electrodes being spaced relative to said surface so that at each of them there is derived a signal having a first non-zero level while said detector is not illuminated by said radiation and a second non-zero level while it is illuminated by said radiation, said first level being subject to change in response to internal conditions of the detector, said second level being dependent upon: the internal conditions, the position of the centroid of said image on the detector surface relative to the electrode, and the intensity of said radiation impinging on the detector; the relative amplitudes of the second levels derived from the plural electrodes providing an indication of the position of the detector and image in two directions at right angles to each other, said spacecraft including means for cyclically chopping the radiation illuminating the detector so that said first and second values are derived in sequence during each chopping cycle while the radiation is respectively blocked and passed by the chopping means, means responsive only to the first signal for deriving a second signal having a level proportional to the first level, said second signal remaining substantially constant throughout a complete chopping cycle, and means, for each electrode, combining the first and second signals for deriving a third signal having a substantially zero level while the firsT level is being derived and a third level substantially proportional to the difference between the first and second levels while the second level is being derived.
Claim 20
Independent Claim
229 words
A device for deriving signals indicative of the angular position of a radiation emitting celestial body comprising a spacecraft, a detector for the radiation positioned on the spacecraft, means for forming a radiation image of the body on the detector, said image having an area much less than the detecting surface of the detector, said detector having a planar detecting surface with substantial lengths in two directions at right angles to each other, said detector including a plurality of output electrodes being spaced relative to said surface so that at each of them there is derived a signal having a first non-zero level while said detector is not illuminated by said radiation and a second non-zero level while it is illuminated by said radiation, said first level being subject to change in response to internal conditions of the detector, said second level being dependent upon: the internal conditions, the position of the centroid of said image on the detector surface relative to the electrode, and the intensity of said radiation impinging on the detector, the relative amplitudes of the second levels derived from the plural electrodes providing an indication of the position of the detector and image in two directions at right angles to each other, wherein said image forming means is a pin hole having an area no greater than approximately one-tenth the area of the detecting surface.
Claim 21
Independent Claim
229 words
A device for deriving signals indicative of the angular position of a radiation emitting celestial body comprising a spacecraft, a detector for the radiation positioned on the spacecraft, means for forming a radiation image of the body on the detector, said image having an area much less than the detecting surface of the detector, said detector having a planar detecting surface with substantial lengths in two directions at right angles to each other, said detector including a plurality of output electrodes being spaced relative to said surface so that at each of them there is derived a signal having a first non-zero level while said detector is not illuminated by said radiation and a second non-zero level while it is illuminated by said radiation, said first level being subject to change in response to internal conditions of the detector, said second level being dependent upon: the internal conditions, the position of the centroid of said image on the detector surface relative to the electrode, and the intensity of said radiation impinging on the detector, the relative amplitudes of the second levels derived from the plural electrodes providing an indication of the position of the detector and image in two directions at right angles to each other, wherein said image forming means is a pin hole having an area no greater than approximately one-tenth the area of the detecting surface.
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) | 1976-07-09 | 1977-01-08 | 1977-07-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-07-09 | 1981-01-08 | 1981-07-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-07-09 | 1985-01-08 | 1985-07-10 | $7700.00 | Window Closed / Lapsed |