US6137437A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Spaceborne scatterometer
Assignee: European Space Agency
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Filing: 1999-03-24
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Granted: 2000-10-24
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Expires: 2019-03-24
Abstract
Abstract A scatterometer orbiting around the earth globe comprises a single fanbeam radar antenna which is rotated around a vertical axis, at a slow rotation rate. The antenna foot-print sweeps a circular disc. The slow conical sweep combined with the motion of the satellite on which the scatterometer is mounted results in highly overlapping successive sweeps such that an image pixel is revisited many times during an overpass. The pixels in the radial direction are resolved by range-gating the radar echo. The radar operates in the C-band. The scatterometer is intended, in particular, to determine wind speed and direction over the ocean.
Inventors
- 👤 Chung-chi Lin
- 👤 John Julian William Wilson
- 👤 Fabrizio Impagnatiello
- 👤 Peter Park
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 03:04
CPC Classifications
G; G01; G01S; G01S13/00; G01S13/88; G01S13/95; G01S13/955; G01S13/02; G01S13/06; G01S13/42; G01S13/422; G01S13/08; G01S13/10; G01S13/26; G01S13/28; Y; Y02; Y02A; Y02A90/00; Y02A90/10
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
181 words
A scatterometer mounted on-board a spacecraft orbiting around the Earth at a determined speed for acquiring points over a strip of an Earth surface measuring determined physical parameters based upon the acquired point, comprising: a single antenna continuously rotated at a determined rotation rate around an axis directed vertical to a sub-spacecraft track on said Earth surface; and a transmitter-receiver coupled to said antenna configured to generate radar signals to illuminate said Earth surface by a fan-beam covering a radially extending footprint that sweeps a circular disc pattern around said vertical axis when said antenna is rotating, to receive radar echo signals echoed from any discrete point of said Earth surface when illuminated by said radar signals, and to derive said physical parameters by processing said radar echo signals, wherein said determined rotation rate, relative to said determined spacecraft speed, provides overlapping successive sweeps each corresponding to a complete rotation of said fan-beam so that any point of said strip across said sub-spacecraft track is acquired during an overpass over said track at least three occasions corresponding to different azimuth angles.
Claim 2
Dependent Claim
181 words
A scatterometer mounted on-board a spacecraft orbiting around the Earth at a determined speed for acquiring points over a strip of an Earth surface measuring determined physical parameters based upon the acquired point, comprising: a single antenna continuously rotated at a determined rotation rate around an axis directed vertical to a sub-spacecraft track on said Earth surface; and a transmitter-receiver coupled to said antenna configured to generate radar signals to illuminate said Earth surface by a fan-beam covering a radially extending footprint that sweeps a circular disc pattern around said vertical axis when said antenna is rotating, to receive radar echo signals echoed from any discrete point of said Earth surface when illuminated by said radar signals, and to derive said physical parameters by processing said radar echo signals, wherein said determined rotation rate, relative to said determined spacecraft speed, provides overlapping successive sweeps each corresponding to a complete rotation of said fan-beam so that any point of said strip across said sub-spacecraft track is acquired during an overpass over said track at least three occasions corresponding to different azimuth angles.
Claim 3
Dependent Claim
37 words
A scatterometer according to claim 1, wherein said transmitter-receiver operate in pulsed mode, so that each point of a given echo profile received by said transmitter-receiver can be attributed to a unique pixel position within said foot-print.
Claim 4
Dependent Claim
30 words
A scatterometer according to claim 2, wherein said transmitter-receiver is further configured to resolve position of each of the acquired points within said strip by range-gating said radar echo signals.
Claim 5
Dependent Claim
51 words
A scatterometer according to claim 3, wherein a ground-speed component of the determined spacecraft speed along said sub-spacecraft track is approximately equal to 7 km/s and said antenna rotation rate is 3.3 rpm, so that each said foot-print is overlapped to a previous one by about 70% along said sub-spacecraft track.
Claim 6
Dependent Claim
16 words
A scatterometer according to claim 1, wherein said antenna comprises a passive array having slotted waveguides.
Claim 7
Dependent Claim
11 words
A scatterometer according to claim 5, wherein said antenna is rectangular.
Claim 8
Dependent Claim
18 words
A scatterometer according to claim 1, wherein said spacecraft is orbiting along a 725 km height circular orbit.
Claim 9
Dependent Claim
31 words
A scatterometer according to claim 1, wherein said print-foot is formed between an inner circle and an outer circle, corresponding to utmost incidence angles of said fanbeam between 28° and 51°.
Claim 10
Dependent Claim
12 words
A scatterometer according to claim 1, wherein said transmitter-receiver operates in C-band.
Claim 11
Dependent Claim
20 words
A scatterometer according to claim 1, wherein said physical parameters to be measured are wind speed and direction over oceans.
Claim 12
Dependent Claim
19 words
A scatterometer according to claim 1, wherein said physical parameters to be measured are land surfaces and ice characteristics.
Claim 13
Independent Claim
163 words
A method of acquiring points over a strip of the Earth surface and measuring determined physical parameters of each of the acquired points, the method comprising: continuously rotating a single antenna at a determined rotation rate around an axis directed vertical to a sub-spacecraft track on said Earth surface; generating radar signals for illuminating said Earth surface by a fan-beam covering a radially extending footprint that sweeps a circular disc pattern around said vertical axis when said antenna is rotating; and receiving radar echo signals echoed from any discrete point of said Earth surface when illuminated by said radar signals and deriving said physical parameters by processing said radar echo signals, wherein said determined rotation rate, relative to said determined spacecraft speed, provides overlapping successive sweeps each corresponding to a complete rotation of said fan-beam so that any of said strip across said track is acquired during an overpass over said track at at least three occasions each corresponding to different azimuth angles.
Claim 14
Independent Claim
163 words
A method of acquiring points over a strip of the Earth surface and measuring determined physical parameters of each of the acquired points, the method comprising: continuously rotating a single antenna at a determined rotation rate around an axis directed vertical to a sub-spacecraft track on said Earth surface; generating radar signals for illuminating said Earth surface by a fan-beam covering a radially extending footprint that sweeps a circular disc pattern around said vertical axis when said antenna is rotating; and receiving radar echo signals echoed from any discrete point of said Earth surface when illuminated by said radar signals and deriving said physical parameters by processing said radar echo signals, wherein said determined rotation rate, relative to said determined spacecraft speed, provides overlapping successive sweeps each corresponding to a complete rotation of said fan-beam so that any of said strip across said track is acquired during an overpass over said track at at least three occasions each corresponding to different azimuth angles.
Claim 15
Dependent Claim
176 words
A scatterometer system for acquiring points over a strip of an Earth surface and measuring determined physical parameters of each of the acquired points, comprising: a single fan-beam antenna rotating at a slow rotation rate around an axis directed vertical to a sub-spacecraft track on said Earth surface; and a transmitter-receiver coupled to said antenna, the transmitter-receiver being configured to generate radar signals for illuminating said Earth surface by a fan-beam covering a radially extending footprint that sweeps a circular disc pattern around said vertical axis when said antenna is rotating, and to receive radar echo signals echoed from any discrete point of said earth surface when illuminated by said radar signals, the transmitter-receiver deriving said physical parameters by processing said radar echo signals, wherein said determined rotation rate, relative to said determined spacecraft speed, provides overlapping successive sweeps each corresponding to a complete rotation of said fan-beam so that any point of said strip across said track is acquired during an overpass over said track at at least three occasions corresponding to different azimuth angles.
Claim 16
Dependent Claim
176 words
A scatterometer system for acquiring points over a strip of an Earth surface and measuring determined physical parameters of each of the acquired points, comprising: a single fan-beam antenna rotating at a slow rotation rate around an axis directed vertical to a sub-spacecraft track on said Earth surface; and a transmitter-receiver coupled to said antenna, the transmitter-receiver being configured to generate radar signals for illuminating said Earth surface by a fan-beam covering a radially extending footprint that sweeps a circular disc pattern around said vertical axis when said antenna is rotating, and to receive radar echo signals echoed from any discrete point of said earth surface when illuminated by said radar signals, the transmitter-receiver deriving said physical parameters by processing said radar echo signals, wherein said determined rotation rate, relative to said determined spacecraft speed, provides overlapping successive sweeps each corresponding to a complete rotation of said fan-beam so that any point of said strip across said track is acquired during an overpass over said track at at least three occasions corresponding to different azimuth angles.
Claim 17
Dependent Claim
38 words
The system according to claim 13, wherein the transmitter-receiver operates in pulsed-mode to attribute a unique pixel position within said footprint, the transmitter-receiver computing position of the acquired point within said strip by range-gating said radar echo signals.
Claim 18
Dependent Claim
166 words
A signal produced by a method of acquiring points over a strip of the Earth surface and measuring determined physical parameters of each of the acquired points, the method comprising: continuously rotating a single antenna at a determined rotation rate around an axis directed vertical to a sub-spacecraft track on said Earth surface; generating radar signals for illuminating said Earth surface by a fan-beam covering a radially extending footprint that sweeps a circular disc pattern around said vertical axis when said antenna is rotating; and receiving radar echo signals echoed from any discrete point of said Earth surface when illuminated by said radar signals and deriving said physical parameters by processing said radar echo signals, wherein said determined rotation rate, relative to said determined spacecraft speed, provides overlapping successive sweeps each corresponding to a complete rotation of said fan-beam so that any of said strip across said track is acquired during an overpass over said track at least three occasions each corresponding to different azimuth angles.
Claim 19
Dependent Claim
166 words
A signal produced by a method of acquiring points over a strip of the Earth surface and measuring determined physical parameters of each of the acquired points, the method comprising: continuously rotating a single antenna at a determined rotation rate around an axis directed vertical to a sub-spacecraft track on said Earth surface; generating radar signals for illuminating said Earth surface by a fan-beam covering a radially extending footprint that sweeps a circular disc pattern around said vertical axis when said antenna is rotating; and receiving radar echo signals echoed from any discrete point of said Earth surface when illuminated by said radar signals and deriving said physical parameters by processing said radar echo signals, wherein said determined rotation rate, relative to said determined spacecraft speed, provides overlapping successive sweeps each corresponding to a complete rotation of said fan-beam so that any of said strip across said track is acquired during an overpass over said track at least three occasions each corresponding to different azimuth angles.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2003-10-24 | 2004-04-24 | 2004-10-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2007-10-24 | 2008-04-24 | 2008-10-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2011-10-24 | 2012-04-24 | 2012-10-24 | $7700.00 | Window Closed / Lapsed |