Usage and Protection of the Earth Exploration Satellite Service J. Piepmeier NASA Goddard Space...

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 AssemblyMontréalJuly 14, 2008

July 14, 2008 1Piepmeier - COSPAR, Montreal

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.• NASA’s Earth Observing System covers 6.9 GHz – 2.5 THz


JAXA’s AMSR-E on NASA’s EOS Aqua

July 14, 2008 Piepmeier - COSPAR, Montreal 3

6.9, 10.7, 18.7, 23.4, 36.5, 89 GHz

Oceanographic Data Products


1998 Hurricane Bonnie

Sea Surface Temperature

From TRMMMicrowaveImager

http://earthobservatory.nasa.gov/Newsroom/NewImages/Images/trmm_sst.jpg

1998 Hurricane Danielle

Aircraft sortie

Danielle Microwave Imagery (10.7 – 325 GHz)

X K wv

Ka W

Imaged from NASA’s DC-8 and ER-2 on August 30, 1998

Air Temperature Decadal Trend


Decadal trends (1979-2007) in Microwave Sounding Unit channel for Lower Troposphere (~<5km) 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.

Frequencies for Observing over Ocean


Frequencies for Observing over Land


12

RFI Index: TB6H - TB10H

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/WentzCourtesy: E. Njoku, JPL

July 14, 2008 Piepmeier - COSPAR, Montreal

RFI in Spaceborne Radiometers

Frequency Band

Confirmed or Potential

Instruments Nature of RFI

L-band Potential SMOS/MIRASAquarius/SAC-D, SMAP

Likely to be OOB emissions from terrestrial radars

C-band Confirmed

Expected

SMMR on SeaSat and Nimbus 7 AMSR-E on EOS AquaWindSat on Coriolis MIS on NPOESS

Majority is likely fixed service (FS) communcations. Mobile service (MS) and radiolocation possible. Proliferation of Part 15 UWB devices expected.

X-band Confirmed Potential

AMSR-E, WindSat GMI on GPM core satellite MIS

Allocation shared with FS. WindSat uses extended band up into Direct Broadcast Service (DBS).

K-band 24 GHz Potential MIS and GMIATMS on NPP (and NPOESS)

Allocation shared with Fixed Satellite Service (FSS) S-E links and FS. No confirmed cases. Shared with UWB vehicular radars. No RFI experienced.

Ka-Band Potential MIS and GMI Allocation shared with FS and MS. No confirmed cases.

V-band Potential ATMS PATH from NRC Decadal Survey

Part-15 devices growth explosion expected. Allocation shared with inter-satellite service links visible from GEO.


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)


Spectrum Allocation


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)


AN/FPS-108 COBRA DANE

worst case = 1 W at Aquarius ~ 1012 K

MUST LIMIT POWER


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


AQUARIUS FPS-117 FDR - 25 MHz BW 7-Pole, 9-Pole & Brick Wall Filter Comparison

1385 MHz

1400 MHz


Filtering is not enough!

Aquarius West Coast PathStart: Lat=-125, Lon=-3 deg


AQUARIUS Radiometer

Radars start to be

visible


0.1 K0.01 K0.001 K

AQUARIUS Radiometer

• Detect pulses• 3 x Nyquist sampling of

radar azimuth beam


0.1 K

0.01 K

0.001 K

10 ms

-240 -220 -200 -180 -16010

-5

10-4

10-3

10-2

10-1

100

CC

DF

P int (dBW)

Real Life Aquarius RFI in Ground Experiment


0 200 400 600 800 1000 1200-20

0

20

40

60

80

time (s)

T

B

0 200 400 600 800 1000 1200-2

-1

0

1

2

3

time (s)

T

B

10-ms integration

2.88-s integration

Prediction is 1000X worse over land!

100 K10 K1 K0.1 K0.01 K


L-band Interference Suppressing Radiometer

256K FIFO10-bit A/D’s

Digital filters/ APB/FFT/Integrator

Threshold

NBLANK

NWAIT

NSEP

Real-time removal of pulsed interference

APB off APB on

• Two 200 MSPS, 10 bit ADC’s: 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

Courtesy: J. Johnson, Ohio State

27Piepmeier - COSPAR, Montreal

Agile Digital Detector - University of Michigan

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

– <V*H> 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

Aircraft prototype ADD and automated C&DH for scientific demonstrations in a relevant environment

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.

ADD spaceflight prototype brassboard. Analog signal RF and clock inputs at right.

28Piepmeier - COSPAR, Montreal

Soil Moisture-Active/Passive


NASA’s first Decadal Survey MissionLaunched scheduled for 2013

L-band microwave radiometer and SAR

Regulatory Approach - EESS


RAS Regulatory Framework


EESS and RAS - Common Organizations


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 f>275 GHz

• Solution space– Regulatory– Technological


Usage and Protection of the Earth Exploration Satellite Service J. Piepmeier NASA Goddard Space...

Documents

Transcript of Usage and Protection of the Earth Exploration Satellite Service J. Piepmeier NASA Goddard Space...