Four-frequency, linearly-polarized, passive microwave
radiometric system which measures atmospheric, ocean and terrain
microwave brightness temperatures at 19.35, 22.235, 37.0, and 85.5
GHz. [1] The four frequencies are sampled in both horizontal and
vertical polarizations, except the 22.235 GHz which is sampled in
the vertical only. It was first commissioned in June 1987 aboard
Defense Meteorological Satellite Program (DMSP) F-8 satellite and
latter flown aboard the following DMSP satellites F-10, F- 11,
F-12, F-13 and F-15.[2]
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The scanning multichannel microwave radiometer (SMMR)-the NASA
Nimbus -7 satellite for around nine years (1978-1987),the SMMR was
a ten channel instrument and dual polarized The Special Sensor
Microwave Imager / Sounder (SSMIS), is an enhanced eleven- channel,
eight-frequency system. launched on Oct 18 2003 aboard the DMSP
F-16 satellite and recently flown aboard DMSP F-17 and F-18
satellites.
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Its main objective is to support the Department of Defence
(DoD) activities but the data can be released to the scientific
community to extract information on some global hydrological
parameters like water vapour, cloud water and precipitation It
measures ; Atmospheric, ocean, and terrain microwave brightness
temperatures (similar to NIMBUS-7 SMMR) which are converted into
environmental parameters such as: sea surface winds, rain rates,
cloud water, precipitation, soil moisture, ice edge, and ice age.
Used to obtain synoptic maps of critical atmospheric, oceanographic
and selected land parameters on a global scale
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The SSM/I sensor executes a 45 conical scan of the Earth's
surface from nadir. This gives a nominal incidence (zenith) angle
of 53.1 to the Earth's surface from the nominal orbit. Only part of
the possible 360 scan in azimuth is used to collect data. The
active azimuth scan angle is 102.4 is ahead of the S/C for an
afternoon ascending orbit and behind the S/C for a morning
ascending orbit.
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It rotates continuously about an axis parallel to the local
spacecraft vertical at 31.6 rpm and measures the upwelling scene
brightness temperatures over an angular sector of 102.4 deg about
the sub-satellite track. This results in a swath width of
approximately 1400 km. The spin rate provides a period of 1.9 sec
during which the spacecraft sub-satellite point travels 12.5 km.
Each scan 128 discrete uniformly spaced radiometric samples are
taken at the two 85 GHz channels and, on alternate scans, 64
discrete samples are taken at the remaining 5 lower frequency
channels. The antenna beam intersects the Earth's surface at an
incidence angle of 53.1 deg (as measured from the local Earth
normal
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MAIN REFLECTOR ANTENNA FEED HOT LOAD REFERENCE COLD SKY
REFLECTION S OLS POWER SUBSYSTEM BAPTA DIGITAL DATA SUBSYSTEM BAPTA
CONTROL ELECTRONIC S RADIOMETE R RECEIVER MOMENTUM COMPENSATIO N
STRUCTURE AND THERMAL CONTROL SPACECRAFT DATA POWER COMMANDS AND
TIMING TELEMETRY
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ISOLAT OR FEED MIXER GAIN SET DECISION AND REGISTER BP FILTER
IF AMP SQUARE LAW DETECTOR OFFSET GAIN COMMAND VIDEO AMP INTEGRAT E
HOLD DUMP GUNN LOCAL OSC
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SENSITIVITY -
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CALIBRATION Hot load target Two microwave reference target. Tb
= Tc + (Th Tc )* (Vb Vc/Vh Vc) Inst Err = Tb - Tvar
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APPLICATIONS SDR- EDR
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REFERENCES J. P. Hollinger, J. L. Peirce, G. A. Poe, SSM/I
USERS GUIDE 14 SEPTEMBER 1987 Chris Allen EECS 823 CLASS NOTES 10
DECEMBER 2014
https://directory.eoportal.org/web/eoportal/satellite-
missions/d/dmsp-block-5d#references
