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OVERVIEW OF SENSORS FOR APPLICATIONS
Deepak PutrevuHead, MTDD/AMHTDG
Visible 0.4-0.7μmNear infrared (NIR) 0.7-1.5μmShortwave infrared (SWIR) 1.5-3.0μmMid-wave infrared (MWIR) 3.0-8.0μmLongwave IR(LWIR)/Thermal IR(TIR) 8.0-15μmFar infrared (FIR) Beyond15μm
Optical Infrared (OIR) Region
VisibleUVX RaysGamma Rays NIR SWIR Thermal IR Microwave
EM SPECTRUM
Microwave RegionP-band: ~0.25 – 1 GHzL-band: 1 -2 GHzS-band: 2-4 GHzC-band: 4-8 GHzX-band: 8-12 GHzKu-band: 12-18 GHzK-band: 18-26 GHzKa-band: 26-40 GHzV-band: 40 - 75 GHzW-band: 75-110 GHzmm-wave: 110 – 300GHz
•Sensors are 24x365
•Signal data characteristics
unique to the microwave
region of the EM spectrum
•Response is primarily
governed by geometric
structures and hence
complementary to optical
imaging
Basic Interactions between Electromagnetic
Energy and the Earth’s Surface
Emissivity: The ratio of the observed flux emitted by a body or surface to that of a blackbody under the same condition.
Absorptivity: the fractional part of the incident radiation that is absorbed by the surface.
Reflectivity: The fractional part of the incident radiation that is reflected by the surface.
Transmissivity: The fractional part of the radiation transmitted through the medium.
Incident radiation, P
Power reflected, ρP
Power absorbed, αP
Power transmitted, τP
= Power emitted, εP
P= Pr + Pt + Pa
𝑃𝑟
𝑃+
𝑃𝑡
𝑃+
𝑃𝑎
𝑃= 1
ρ + τ + α =1
At thermal equilibrium, absorption and emission are the same.
Dominant mechanisms measured by sensors
1) Reflection 2) Emission
Optical camerasLIDARsRADARs
Radiometers
What are passive and active sensors?
Sensors which carry their own source of illumination to measure reflection / scattering are called active sensors
(LIDARs and RADARs)
And, those which do not require are passive sensors(Cameras & Radiometers)
MEGHA-
TROPIQUES
INSAT-3AOCEANSAT-2
SARAL
RISAT-1
RESOURCESAT-2, 2A
RISAT-2
CARTOSAT-2; 2A; 2B
CARTOSAT-1
KALPANA
INSAT-3D
LAND & WATER HIGH RESOLUTION OCEAN WEATHER; CLIMATE
EARTH OBSERVATION SATELLITES
1 KM 0.8 MIMAGING CAPABILITY
(2012)
(2011, 16)
(2012) (2005)
(2007, 08, 10)
(2016, 17, 17)
(2013)
(2009)
(2011)
(2002)
(2003)
(2013)
CARTOSAT-2S
SCATSAT-1(2016)
INSAT-3DR(2016)
RADIOMETERS(Used To Measure Ocean Parameters Like Wind Speed, Sea Surface Temperature And Precipitation For Weather Forecasting)
DELIVERED1. SAMIR On Bhaskara-1(1978)2. SAMIR On Bhaskara-2(1981) 3. Microwave Scanning Microwave
Radiometer (MSMR) On Oceansat-1(1999)
4. MADRAS On Meghatrophiques(2011)
SCATTEROMETERS(Used To Measure Wind Velocity, On Ocean SurfaceFor Weather Forecasting)
DELIVERED1. Ku-band Scatt onbrd Oceansat-2
(2009)2. Scatsat-1(2016)
ONGOING:Oceansat-3 Scatterometer
MILLI-METER WAVE SOUNDER(Used To Measure Atmospheric Temperature & Humidity Profiles For Weather Forecasting)
Temperature Sounding Unit (TSU)Humidity Sounding Unit (HSU)
For Moon Dual Frequency (L &
S-BAND) SAR On Chandrayaan-2 (2017)
Ka-band Altimeter as Navigation and Guidance Sensor
Ongoing ..
For Mars P-band SAR Radiometer
For Venus S-band SAR Radiometer RO payload
PlanetaryLand
Synthetic Aperture Radar (SAR)(Imaging Sensor For Land-mapping With Civilian And Strategic Applications)
SPACEBORNE:DELIVERED:
C-BAND SAR on Radar Imaging Satellite (RISAT-1) (2012)
ONGOING:NISAR (S-Band SAR)RISAT-1A (Repeat of RISAT-1)
X-BAND SAR (RISAT-2A, 2B)
AIRBORNE:FLOWN:
Airborne SAR (ASAR) (1992)Disaster Management SAR
(DMSAR) – C-BAND (2005)L&S-band Airborne SAR (2017)
ONGOING:DMSAR – C-BANDDMSAR - X-BAND
GB ScattGround Penetration Radar - GPR
AtmosphereOcean
Microwave Remote Sensing @ SAC
9.6 GHZ, HH 25 KW PEAK POWER ALTITUDE 3 KM SWATH of 5 Kms PLATFORM DAKOTA DC-10 (Aircraft)
X-band SLAR – Side Looking Airborne Radar (1983-89)
The ‘BASIC’ Radar
Synthetic Aperture Radar
•MAKES USE OF DOPPLER VARIATION BETWEEN
SENSOR AND TARGET
•RESOLUTION: Rλ/2LSYN = L/2
•SAR RESOLUTION INDEPENDENT OF RANGE
Velocity
First Flown On May 20th, 1992
C-band ASAR – Airborne Synthetic Aperture Radar
The ‘BASIC’ Radar+ Signal Processing for Azimuth
resolution improvement= Synthetic Aperture Radar
Kansi
Jalwara
Rampur
*
*
*
Sabhan*
DARBHANGA
LAHERIA SARAI
Kamrauli
*
Baliya*
Banauli *Yaunga *
Dih Rampur *
Panchobh * Mahnauli*
Kamalpur *Baghla *
Baghia
*
Taralahi * Chandih *
Ekmighat*
Badhbasti
* Simra *
Bajrdpur*
Ballapur*
Baluwahi
*
Manlari
*Ganawli*
Kadaria*
Bharaul
*
Chatiriya*
FLOOD INUNDATION
During Floods - ASAR data of 24-Jul-2003
Affected Embankment
DMSAR Rack Inside The Aircraft
C-band Disaster Management SAR (DMSAR)
DMSAR ANTENNA BEING INSTALLED
BEECHCRAFT
AHMEDABAD AIRPORT
FRS1/FRS2 Mode
53
6 k
m
HRS Mode
CRS Mode
MRS Mode
HRS ModeResolution = 1 - 2 m, o = -16dB
FRS-1 ModeResolution = 3 - 6 m, o = -17dB
FRS-2 ModeResolution = 6 m (circular), 6-9m (QuadPol), o = -20dB / -19dB
MRS ModeResolution = 25 m, o = -17dB
CRS ModeResolution = 50 m, o = -17dB
C-band Radar Imaging Satellite
•India’s first spaceborne SAR, active array,
indigenous
•High resolution to wide swath modes
•Polarimetry mode
Andaman Sea
Pali, Rajasthan
Antarctica Sea IceTunisia
SABARMATI
OIL SPILL, NORWAY
AHMEDABADAndaman Sea
Hybrid Polarimetry results
Odd bounce: BLUEEven bounce: REDVol scattering: GREEN
•Circular Transmit and Linear
Receive (H &V)
• Derivation of Stokes parameters
and decomposition for target
characterization
L & S-band NISAR (NASA-ISRO SAR)
•Dual frequency SAR based on SweepSAR technique.
•High resolution (~6m) and wide swath (240km)
simultaneously
•Airborne version developed for technology
demonstration and L & S-band science data
generation
L & S-band Airborne SAR•First phase of flight campaign over; more to follow
•Data analysis is in progress
Airborne SAR L-band Full Pol Data
@ Shoolpaneshwar forest, Narmada
EVEN
VOLUME
ODD
Freeman-Durden Decomposition Image
11.2 rpm
43.3°Conical scan of MSMR antenna and imaging geometry
Multifrequency Scanning Microwave Radiometer (MSMR) (1999)
6.6 GHz Sea surface Temperature
10.65GHz Wind speed
18GHz Precipitation
21 GHz Cloud Liquid water
Oceansat-2 Ku-band Scatterometer (2009) (OSCAT)
42.620
49.380
Scatterometers measure surface backscatter cross-section with very high accuracy.
Surface roughness α wind velocityRoughness direction: max in the direction of the wind and min orthogonal to the wind
Thane Cyclone, India (28-12-2011)
Neelam Cyclone, India(31-10-2012)
Kabayan Cyclone, Phillipines(01-08-2011)
Phailin Cyclone, India(11-10-2013)
Irene Hurricane, USA(27-08-2011)
Sandy Hurricane, USA (29-10-2012)
Some of the Cyclones tracked by OSCAT
SCATSAT-1: 2016
• Wind speed range improved from 4 – 24m/s (OSCAT) to 3 – 30m/s (Scatsat-1) • Wind vector cell size improved from 40km x 40km (OSCAT) to 25km x 25km
(Scatsat-1)• Other improvements include a host of system and operational features to
improve overall accuracy.
Sea Ice Thickness Testing Ice Sheet Thickness Testing
An initiative with a difference, this instrument looks beneath earth surface.
250-750 MHz stepped frequency subsurface imaging
GPR is part of several expeditions to Antarctica for ice/snow studies
Ground Penetration Radar (GPR)
Signatures in Optical and IR regions
Set of characteristics by which a material or an object may be identified on an image or photograph.
•Interpretation of optical images requires knowledge of spectral reflectance signatures of various materials (natural or man-made)
RESOURCESAT SENSORS
Specification LISS-IV LISS-III AWiFS Instantaneous Geometric Field of View (m)
5.8 at nadir (Across Track)
23.5 56 at nadir (Across Track)
Spectral Bands (micrometer)
B2: 0.52-0.59 B3: 0.62-0.68 B4: 0.77-0.86
B2: 0.52-0.59 B3: 0.62-0.68 B4: 0.77-0.86 B5: 1.55 – 1.70
B2: 0.52-0.59 B3: 0.62-0.68 B4: 0.77-0.86 B5: 1.55 – 1.70
Swath (km) 23.9 (MX) 70 (mono)
141 740 (combined) 370 (each head)
LISS-IV
AWiFS
LISS-III
SENSORS IN RESOURCESAT SATELLITE
SENSORS IN CARTOSAT SATELLITE
HYPER SPECTRAL IMAGING SPECTROMETER
High spectral resolution spectroscopy has capability to detect sharp absorption features (which is averaged out in broad band) manifested due to composition and certain physical, chemical and biophysical condition of material
Hyperspectral Imaging
More than 100 bands with high resolution (~5nm) closely spaced (continuum) bands
…. 100’s of parallel spectrometers
AVIRIS-NG Airborne Hyperspectral Campaign In collaboration with JPL/NASA
(Airborne Visible/Infrared Imaging Spectrometer – NextGen)
Airborne data acquisition over 57 sites in 84 days
Radiance data is used to generate surface reflectance data in 425 bands (VNIR and SWIR – 380 to 2510nm with at 5 nm sampling)
LIDAR REMOTE SENSING OF ATMOSPHERE
LIDAR: LIght Detection And Ranging
LIDAR REMOTE SENSING OF VEGETATION
LIDAR: LIght Detection And Ranging
Thanks