Usage and Protection of the Earth Exploration Satellite Service

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Usage and Protection of the Earth Exploration
Satellite Service J. Piepmeier NASA Goddard Space
Flight Center Microwave Instrument Technology
Branch Greenbelt, Maryland USA
COSPAR Scientific Assembly Montréal July 14, 2008
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Earth Exploration Satellite Service

• Since 1972, spaceborne microwave radiometers have
  provided all-weather day-night
  observations of our planet
• Over 25 environmental variables are estimated
  from microwave data
• Data used in operational and research weather
  prediction, climatology research and monitoring,
  and environmental observation.
• NASAs Earth Observing System covers 6.9 GHz
  2.5 THz

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JAXAs AMSR-E on NASAs EOS Aqua
6.9, 10.7, 18.7, 23.4, 36.5, 89 GHz
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Oceanographic Data Products
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1998 Hurricane Bonnie
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Sea Surface Temperature
From TRMM Microwave Imager
http//earthobservatory.nasa.gov/Newsroom/NewImage
s/Images/trmm_sst.jpg
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1998 Hurricane Danielle
Aircraft sortie
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Danielle Microwave Imagery (10.7 325 GHz)
Imaged from NASAs DC-8 and ER-2 on August 30,
1998
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Air Temperature Decadal Trend
Decadal trends (1979-2007) in Microwave Sounding
Unit channel for Lower Troposphere (lt5km)
Temperature (oC). Data poleward of 82.5 North
and 70 South, as well as areas with land or ice
elevations above 3000 meters, are not available
and are shown in white.
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Frequencies for Observing over Ocean
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Frequencies for Observing over Land
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Global Radio Frequency Interference (RFI)
RFI contamination occurs at both 6.9 GHz
(widespread in U.S., Middle East, Asia) and 10.7
GHz (mainly in England, Italy, Japan)
MicroRad-2004 - Rome, Italy
Ashcroft/Li/Njoku/Wentz
Courtesy E. Njoku, JPL
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RFI in Spaceborne Radiometers
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Engineering Approach SOE

• Survivability avoid damage from RFI
• Operability
• Measure without error in the presence of
  interference
• Receiver selectivity
• Excisability
• Receive interference but can remove it
• Detection and excision
• Spectral (sub-banding)
• Temporal (pulse blanking)
• Statistical or amplitude (kurtosis)

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Spectrum Allocation
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Terrestrial Long-Range Radars

• Operate in radio-location service
• Highest power with widest spectrum
• List of U.S. L-band radars used
• Aerostat (L-88) 12 radars
• AN/FPS-108 1 radar
• AN/FPS-117 31 radars
• AN/FPS-124 39 radars
• ARSR-1 23 radars
• ARSR-2 17 radars
• ARSR-3 14 radars
• ARSR-4 42 radars
• Multiple military (Army, Navy, USMC) radars not
  included
• No technical data available on most
• No location data available on all (mobile)

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AN/FPS-108 COBRA DANE
worst case 1 W at Aquarius
1012 K MUST LIMIT POWER
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Frequency Analysis for Operability

• How much selectivity is enough?
• Use worst offender AN/FPS-117 within U.S.
• 25 kW peak (4 kW average) transmitter
• 39 dBi gain antenna
• 1383 MHz maximum frequency in NTIA filings
• Frequency Dependent Rejection method
• Transmitter spectrum
• Receiver bandpass response
• Rejection based on frequency offset

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AQUARIUS FPS-117 FDR - 25 MHz BW 7-Pole, 9-Pole
Brick Wall Filter Comparison
1385 MHz
Filtering is not enough!
1400 MHz
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Aquarius West Coast PathStart Lat-125, Lon-3
deg
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AQUARIUS Radiometer
Radars start to be visible
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AQUARIUS Radiometer

• Detect pulses
• 3 x Nyquist sampling of radar azimuth beam

10 ms
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Real Life Aquarius RFI in Ground Experiment
10-ms integration
2.88-s integration
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Prediction is 1000X worse over land!
100 K 10 K 1 K 0.1 K 0.01 K
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L-band Interference Suppressing Radiometer

• Two 200 MSPS, 10 bit ADCs can sample either a
  100 MHz channel or 2 pols at 50 MHz each,
  real-time asynchronous pulse blanking (APB)
  algorithm
• Su 05 Canton campaign results

Real-time removal of pulsed interference
Courtesy J. Johnson, Ohio State
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Agile Digital Detector - University of Michigan
Flight line for Texas WB-57 demonstration flight
Images of TB (left) and kurtosis (right) at
Galveston coastal crossing during demo flight.
Kurtosis responds only to non-thermal signals.
Aircraft prototype ADD and automated CDH for
scientific demonstrations in a relevant
environment

• ADD Specifications and Performance
• Direct sampling digitizer of V-pol and H-pol 1413
  MHz radiometer RF signals (no LO required)
• Flight qualified FPGA processor
• ltVHgt complex correlator forms 3rd and 4th Stokes
  TBs
• 2nd moment provides fully polarimetric TB
• 2nd and 4th central moment provides kurtosis
• 16 frequency subbands over full 24 MHz radiometer
  passband permits frequency domain RFI mitigation
• Nyquist oversampling (x600) permits time domain
  RFI mitigation

ADD spaceflight prototype brassboard. Analog
signal RF and clock inputs at right.
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Soil Moisture-Active/Passive
NASAs first Decadal Survey Mission Launched
scheduled for 2013 L-band microwave radiometer
and SAR
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Regulatory Approach - EESS
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RAS Regulatory Framework
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EESS and RAS - Common Organizations
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Closing Thoughts

• EESS and RAS have differences (up vs. down,
  global vs. local)
• EESS and RAS have similarities (broad spectrum
  usage, need for spectrum outside of allocations)
• Collaboration possibilities exist
• Spectrum surveys
• EESS must put RAS technologies into space
• WRC-11 agenda item for fgt275 GHz
• Solution space
• Regulatory
• Technological