No Results Found!
41 Related Articles

Synthetic-aperture radar

synthetic aperture radarSARsynthetic aperture
It is analogous to conventional SAR, except that ISAR technology utilizes the movement of the target rather than the emitter to create the synthetic aperture.
SAR can also be implemented as inverse SAR by observing a moving target over a substantial time with a stationary antenna.

Imaging radar

radar imagingradar imageryimaging
Inverse synthetic aperture radar (ISAR) is a radar technique using Radar imaging to generate a two-dimensional high resolution image of a target.
Current radar imaging techniques rely mainly on synthetic aperture radar (SAR) and inverse synthetic aperture radar (ISAR) imaging.

Phased array

phased array radarphased-arrayphased-array radar
This operation is equivalent to (but the inverse of) the generation of a large synthetic aperture phased array antenna formed by the coherent summation of the receiver outputs for varying target / antenna geometries.
Inverse synthetic-aperture radar

Beamforming

beam formingbeamformerAntenna beamforming
beamforming
Inverse synthetic aperture radar (ISAR)

Aperture synthesis

aperture synthesis imagingsynthetic apertureinterferometric imaging
This operation is equivalent to (but the inverse of) the generation of a large synthetic aperture phased array antenna formed by the coherent summation of the receiver outputs for varying target / antenna geometries.
Synthetic aperture radar (SAR) and Inverse synthetic aperture radar (ISAR)

Doppler effect

Dopplerdoppler shiftDoppler shifts
ISAR images are often produced by rotating the target and processing the resultant Doppler histories of the scattering centers.

Azimuth

azimuthalazimuthal angleazimuth angle
If the target rotates in azimuth at a constant rate through a 'small' angle, scatterers will approach or recede from the radar at a rate depending only on the cross range position- the distance normal to the radar line of sight with the origin at the target axis of rotation.

Frequency

frequenciesperiodperiodic
The rotation will result in the generation of cross range dependent Doppler frequencies which can be sorted spatially by a Fourier transform.

Fourier transform

Fouriercontinuous Fourier transformuncertainty principle
The rotation will result in the generation of cross range dependent Doppler frequencies which can be sorted spatially by a Fourier transform.

Antenna (radio)

antennaantennasradio antenna
This operation is equivalent to (but the inverse of) the generation of a large synthetic aperture phased array antenna formed by the coherent summation of the receiver outputs for varying target / antenna geometries.

Sine wave

sinusoidalsinusoidsine
If the target is rotated through 'large' angles, the Doppler frequency history of a scatterer becomes non linear, following a sine-wave trajectory.

216 Kleopatra

Kleopatra
A particularly beautiful example of this is the so-called "dog's bone" 216 Kleopatra asteroid, which lies roughly 20% further away from the earth than does the sun.

Autofocus

auto focusAFauto-focus
Unknown target or antenna motion: Unmodeled motion will cause the target image to defocus and be at an incorrect location. This error is controlled by suitable mechanical design or by the use of auto-focus techniques. This error can be measured by the analytic signal phase measurement method described earlier.

Slant range

rangeslant-range
Integrated sidelobe return: ISAR image quality is degraded by range and azimuth compression side lobes. The sidelobes are due to data truncation and can be reduced by the application of appropriate window functions. The sidelobes can cause significant image degradation. First, the peaks of the stronger sidelobes may cause a string of progressively weaker targets to appear on either side of a strong target. Second, the combined power of all sidelobes tends to fog or washout detail in low RCS areas. The integrated sidelobe level can under poor conditions reach a level 10 dB below the peak target return.

Side lobe

sidelobelobesidelobes
Integrated sidelobe return: ISAR image quality is degraded by range and azimuth compression side lobes. The sidelobes are due to data truncation and can be reduced by the application of appropriate window functions. The sidelobes can cause significant image degradation. First, the peaks of the stronger sidelobes may cause a string of progressively weaker targets to appear on either side of a strong target. Second, the combined power of all sidelobes tends to fog or washout detail in low RCS areas. The integrated sidelobe level can under poor conditions reach a level 10 dB below the peak target return.

Truncation

truncatetruncatedtruncating
Integrated sidelobe return: ISAR image quality is degraded by range and azimuth compression side lobes. The sidelobes are due to data truncation and can be reduced by the application of appropriate window functions. The sidelobes can cause significant image degradation. First, the peaks of the stronger sidelobes may cause a string of progressively weaker targets to appear on either side of a strong target. Second, the combined power of all sidelobes tends to fog or washout detail in low RCS areas. The integrated sidelobe level can under poor conditions reach a level 10 dB below the peak target return.

Decibel

dBdecibelsbel
Integrated sidelobe return: ISAR image quality is degraded by range and azimuth compression side lobes. The sidelobes are due to data truncation and can be reduced by the application of appropriate window functions. The sidelobes can cause significant image degradation. First, the peaks of the stronger sidelobes may cause a string of progressively weaker targets to appear on either side of a strong target. Second, the combined power of all sidelobes tends to fog or washout detail in low RCS areas. The integrated sidelobe level can under poor conditions reach a level 10 dB below the peak target return.

Radio frequency

RFradio frequenciesradio-frequency
Target dispersion: Dispersive targets have a non-minimum phase response, appearing to shift in position with RF frequency. Examples of dispersive targets include RF absorbers in which the absorption depth is a function of frequency and various antenna in which the phase center position is frequency dependent. CW ISAR imaging or in some cases preprocessing prior to a FMCW ISAR transform an eliminate dispersive defocusing of the target image.

Jet aircraft

jetjetsjet airplane
Multipath: Multiple reflections can result in ISAR imaging distortions such as the classic ghost image trails from jet aircraft tail pipes.

Optical heterodyne detection

synthetic array heterodyne detectionheterodyneoptical heterodynes
Optical heterodyne detection

List of McDonnell Douglas F-4 Phantom II variants

F-4ERF-4CRF-4E
All 2020s have been fitted with vastly updated suite, including MFDs (multifunction displays) as standard, and incorporating a number of new technologies, such as the new Kaiser El-OP 976 wide-angle HUD and HOTAS system, high performance Elta EL/M-2032 ISAR-capable high-resolution SAR/GMTI (ground moving target indicator) multi-mode fire control radar (developed for the IAI Lavi), IAIC mission computer, new navigation equipment including GPS/INS connected to mapping mode, dual MIL-STD-553B databus managing avionics package, Astronautics Central Air Data Computer, new UHF and IFF packages, airborne video tape recorder (AVTR), Elta EL/L-8222 active ECM pod, Mikes (Aselsan) AN/ALQ-178V3 passive embedded SPEWS, and RWR.

Radar MASINT

counterartillery radarGround Surveillance RadarLCMR
Specialized MASINT radar techniques include line-of-sight (LOS), over-the-horizon, synthetic aperture radar (SAR), inverse synthetic aperture radar (ISAR) and multistatic.

Lockheed P-3 Orion

P-3C OrionP-3 OrionP-3
Several days before the 7 January 1991 commencement of Operation Desert Storm, a P-3C equipped with an APS-137 Inverse Synthetic Aperture Radar (ISAR) conducted coastal surveillance along Iraq and Kuwait to provide pre-strike reconnaissance on enemy military installations.

Advanced Airborne Sensor

Building upon the LSRS, the AAS also has a double-sided AESA radar, which contains a moving target indicator (MTI) that can detect, classify, and track targets on land and at sea at the same time, with synthetic aperture radar (SAR) and inverse synthetic aperture radar (ISAR) for picture-like radar imagery of both inland and ocean areas at the same time; these can profile vessels from a long distance and generate fine resolution without relying on optical sensors, especially in day or night and in adverse weather conditions.