US5381152A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Unfocussed signal processing apparatus for a synthetic aperture radar having a rotating antenna
Assignee: Airbus Defence and Space GmbH
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Filing: 1993-10-05
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Granted: 1995-01-10
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Expires: 2013-10-05
Abstract
Abstract In a rotating antenna synthetic aperture radar, a method and apparatus for unfocussed signal processing for the correlation of the received signals by means of the reference functions. In unfocussed signal processing, only the main portion of the receiving signal S E is used, in which the phase shift is smaller than or equal to 90° for the go-and return-path of the signal. A simplified window function is used as a reference function whose width also corresponds to the main portion of the received signal. Preferably, the in-phase and quadrature component (I r , Q r ) of the window function r are selected to be identical.
Inventors
- 👤 Helmut Klausing
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 21:08
CPC Classifications
G; G01; G01S; G01S13/00; G01S13/88; G01S13/89; G01S13/90; G01S13/904; G01S13/9082
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
144 words
A radar device comprising: at least one transmitter; at least one receiver; at least one antenna for transmitting and receiving radar pulses, said antenna being arranged on the end of a rotating arm; a device for demodulating and intermediately storing received signals; a first processor circuit for forming and storing reference functions based on a predetermined array of system parameters; a correlator for correlating received signals with the reference functions; and an output device for a correlation result; wherein said correlator comprises means, operative when phase shift for a go-and-return path of emitted and received signals is less than or equal to 90°, for performing said correlation using only a main portion of the received signal and a simplified window function in place of the reference function, said window function having a width corresponding to width of the main portion of the received signal.
Claim 2
Dependent Claim
144 words
A radar device comprising: at least one transmitter; at least one receiver; at least one antenna for transmitting and receiving radar pulses, said antenna being arranged on the end of a rotating arm; a device for demodulating and intermediately storing received signals; a first processor circuit for forming and storing reference functions based on a predetermined array of system parameters; a correlator for correlating received signals with the reference functions; and an output device for a correlation result; wherein said correlator comprises means, operative when phase shift for a go-and-return path of emitted and received signals is less than or equal to 90°, for performing said correlation using only a main portion of the received signal and a simplified window function in place of the reference function, said window function having a width corresponding to width of the main portion of the received signal.
Claim 3
Dependent Claim
47 words
Radar device according to claim 1, wherein said predetermined array of system parameters comprises at least one of: illumination geometry of the radar device, distance intervals to be measured, angle of rotation ranges, transmitted pulses as well as the height of the rotating antenna above the ground.
Claim 4
Dependent Claim
22 words
Radar device according to claim 1, wherein said output device comprises at least one of: a display device and an analysis unit.
Claim 5
Dependent Claim
20 words
A radar device according to claim 1, wherein said window function has an in-phase and quadrature component which are identical.
Claim 6
Dependent Claim
47 words
A radar device according to claim 4, wherein the in-phase and quadrature component (I r , Q r ) each comprise a jump function of a scaled value within limits defined by the main portion of the received signal and a value of zero outside these limits.
Claim 7
Dependent Claim
94 words
A radar device according to claim 1, wherein the correlation is performed by means of the window function within a maximum angle of rotation to which the inequality ##EQU13## applies, where R n (t) is a target distance, R SOn is a distance between the antenna and a center line of a strip illuminated by the antenna, and λ is a wavelength of the transmitted signal, and where the illuminated strip is subdivided into N distance intervals, the index n being number of a particular distance interval as a function of radial resolution (1≦n≦N).
Claim 8
Dependent Claim
94 words
A radar device according to claim 5, wherein the correlation is performed by means of the window function within a maximum angle of rotation to which the equation ##EQU14## applies, where R n (t) is a target distance, R SOn is a distance between the antenna and a center line of a strip illuminated by the antenna, and λ is a wavelength of the transmitted signal, and where the illuminated strip is subdivided into N distance intervals, the index n being number of a particular distance interval as a function of radial resolution (1≦n≦N).
Claim 9
Dependent Claim
78 words
A radar device according to claim 6, wherein the maximal angle of rotation for an individual distance interval n is calculated at: E1 ? ##STR1## wherein R gn is distance from a fulcrum of the antenna to a center point of a particular distance interval n, L is a length of a rotating arm which carries the antenna, H O is a height of the antenna above the ground, and λ is the wavelength of the transmitted signal.
Claim 10
Dependent Claim
49 words
A radar device according to claim 1, further comprising a calculating and presetting circuit for subdividing an area in which correlation is performed with the simplified window function, and wherein the received signal is scanned and correlated with a pertaining window function at supporting points determined by said subdivision.
Claim 11
Dependent Claim
48 words
A radar according to claim 5, further comprising a calculating and presetting circuit for subdividing an area in which correlation is performed with the simplified window function, and wherein the received signal is scanned and correlated with a pertaining window function at supporting points determined by said subdivision.
Claim 12
Dependent Claim
48 words
A radar device according to claim 9, wherein the calculating circuit comprises a supporting-point calculating circuit and an increment presetting circuit in which a number and position of the supporting points are determined at which values for the window functions are formed, and the received signals are scanned.
Claim 13
Dependent Claim
48 words
A radar device according to claim 10, wherein the calculating circuit comprises a supporting-point calculating circuit and an increment presetting circuit in which a number and position of the supporting points are determined at which values for the window functions are formed, and the received signals are scanned.
Claim 14
Dependent Claim
33 words
A radar device according to claim 1, wherein ##EQU15## is used as the simplified window function, wherein ±t max is a time assigned to the maximally permissible angle of rotation α max .
Claim 15
Dependent Claim
33 words
A radar device according to claim 5, wherein ##EQU16## is used as the simplified window function, wherein ±t max is a time assigned to the maximally permissible angle of rotation α max .
Claim 16
Dependent Claim
33 words
A radar device according to claim 9, wherein ##EQU17## is used as the simplified window function, wherein ±t max is a time assigned to the maximally permissible angle of rotation α max .
Claim 17
Dependent Claim
33 words
A radar device according to claim 10, wherein ##EQU18## is used as the simplified window function, wherein ±t max is a time assigned to the maximally permissible angle of rotation α max .
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) | 1998-01-09 | 1998-07-11 | 1999-01-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-01-09 | 2002-07-11 | 2003-01-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-01-09 | 2006-07-11 | 2007-01-10 | $7700.00 | Window Closed / Lapsed |