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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