Interferometric synthetic-aperture radar

interferometric synthetic aperture radarInSARSAR interferometryIfSARinterferometryradar interferometrySlope Stability RadarINSAR - Interferometric SARinterferometricinterferometric SAR
Interferometric synthetic aperture radar, abbreviated InSAR (or deprecated IfSAR), is a radar technique used in geodesy and remote sensing.wikipedia
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Synthetic-aperture radar

synthetic aperture radarSARsynthetic aperture
This geodetic method uses two or more synthetic aperture radar (SAR) images to generate maps of surface deformation or digital elevation, using differences in the phase of the waves returning to the satellite or aircraft.
Volcano and earthquake monitoring is a part of differential interferometry.

Remote sensing

remote-sensingremotely sensedremote sensor
Interferometric synthetic aperture radar, abbreviated InSAR (or deprecated IfSAR), is a radar technique used in geodesy and remote sensing.
Conventional radar is mostly associated with aerial traffic control, early warning, and certain large scale meteorological data. Doppler radar is used by local law enforcements’ monitoring of speed limits and in enhanced meteorological collection such as wind speed and direction within weather systems in addition to precipitation location and intensity. Other types of active collection includes plasmas in the ionosphere. Interferometric synthetic aperture radar is used to produce precise digital elevation models of large scale terrain (See RADARSAT, TerraSAR-X, Magellan).

Geodesy

geodeticgeodesistgeodesic
Interferometric synthetic aperture radar, abbreviated InSAR (or deprecated IfSAR), is a radar technique used in geodesy and remote sensing.
Interferometric synthetic aperture radar (InSAR) using satellite images

Digital elevation model

digital terrain modelDEMdigital elevation map
This geodetic method uses two or more synthetic aperture radar (SAR) images to generate maps of surface deformation or digital elevation, using differences in the phase of the waves returning to the satellite or aircraft.
The DEM could be acquired through techniques such as photogrammetry, lidar, IfSAR, land surveying, etc. (Li et al. 2005).

Intermap Technologies

Intermap Technologies Corporation
Airborne InSAR data acquisition systems are built by companies such as the American Intermap, the German AeroSensing, and the Brazilian OrbiSat.
Intermap collects elevation data aerially, using aircraft equipped with Interferometric synthetic aperture radar (IFSAR) technology.

Radarsat-1

Early exploitation of satellite-based InSAR included use of Seasat data in the 1980s, but the potential of the technique was expanded in the 1990s, with the launch of ERS-1 (1991), JERS-1 (1992), RADARSAT-1 and ERS-2 (1995).
This is useful for interferometry and detecting changes at that location that took place during the 24 days.

Shuttle Radar Topography Mission

SRTMhas been
Availability of a suitable DEM may also be a factor for two-pass InSAR; commonly 90 m SRTM data may be available for many areas, but at high latitudes or in areas of poor coverage alternative datasets must be found.
The technique employed is known as interferometric synthetic aperture radar.

ROI PAC

ROI PAC
ROI_PAC is a software package created by the Jet Propulsion Laboratory division of NASA and Caltech for processing SAR images to create InSAR images, named interferograms.

Radar

radar stationradarsradar system
Interferometric synthetic aperture radar, abbreviated InSAR (or deprecated IfSAR), is a radar technique used in geodesy and remote sensing.

Imaging radar

radar imagingradar imageryimaging
This geodetic method uses two or more synthetic aperture radar (SAR) images to generate maps of surface deformation or digital elevation, using differences in the phase of the waves returning to the satellite or aircraft.

Phase (waves)

phasephase shiftout of phase
This geodetic method uses two or more synthetic aperture radar (SAR) images to generate maps of surface deformation or digital elevation, using differences in the phase of the waves returning to the satellite or aircraft. SAR makes use of the amplitude and the absolute phase of the return signal data.

Structural engineering

structuralstructural designstructural engineer
It has applications for geophysical monitoring of natural hazards, for example earthquakes, volcanoes and landslides, and in structural engineering, in particular monitoring of subsidence and structural stability.

Subsidence

land subsidencesubsidedsubsiding
It has applications for geophysical monitoring of natural hazards, for example earthquakes, volcanoes and landslides, and in structural engineering, in particular monitoring of subsidence and structural stability.

Structural stability

structurally stablestabilitydimensional stability
It has applications for geophysical monitoring of natural hazards, for example earthquakes, volcanoes and landslides, and in structural engineering, in particular monitoring of subsidence and structural stability.

Antenna (radio)

antennaantennasradio antenna
SAR is a form of active remote sensing – the antenna transmits radiation that is reflected from the image area, as opposed to passive sensing, where the reflection is detected from ambient illumination.

Electromagnetic radiation

electromagnetic waveelectromagnetic waveselectromagnetic
Radar uses electromagnetic radiation at microwave frequencies; the atmospheric absorption at typical radar wavelengths is very low, meaning observations are not prevented by cloud cover.

Microwave

microwavesmicrowave radiationmicrowave tube
Radar uses electromagnetic radiation at microwave frequencies; the atmospheric absorption at typical radar wavelengths is very low, meaning observations are not prevented by cloud cover.

Amplitude

peak-to-peakintensityvolume
SAR makes use of the amplitude and the absolute phase of the return signal data.

Wavelength

wavelengthsperiodsubwavelength
The phase of the return wave depends on the distance to the ground, since the path length to the ground and back will consist of a number of whole wavelengths plus some fraction of a wavelength.

Radian

radiansradmicroradian
This is measured in radians of phase difference and, because of the cyclic nature of phase, is recorded as repeating fringes that each represent a full 2π cycle.

Reflection (physics)

reflectionreflectedreflective
The phase of the wave may change on reflection, depending on the properties of the material.

Dielectric

dielectricspolarizationdielectric relaxation
The reflected signal back from any one pixel is the summed contribution to the phase from many smaller 'targets' in that ground area, each with different dielectric properties and distances from the satellite, meaning the returned signal is arbitrary and completely uncorrelated with that from adjacent pixels.

Topography

topographicaltopographictopographer
The slight difference in satellite position also alters the distortion caused by topography, meaning an extra phase difference is introduced by a stereoscopic effect.

Stereoscopy

stereoscopicstereoscopic 3D3D
The slight difference in satellite position also alters the distortion caused by topography, meaning an extra phase difference is introduced by a stereoscopic effect.

European Remote-Sensing Satellite

ERSERS-1ERS-2
For sensors like ERS with a small incidence angle this measures vertical motion well, but is insensitive to horizontal motion perpendicular to the line of sight (approximately north-south).