EECS 823 MACHARIA

 Four-frequency, linearly-polarized, passive microwave radiometric system which measures atmospheric, ocean and terrain microwave brightness temperatures at 19.35, , 37.0, and 85.5 GHz. [1] The four frequencies are sampled in both horizontal and vertical polarizations, except the 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]

The scanning multichannel microwave radiometer (SMMR)-the NASA Nimbus -7 satellite for around nine years ( ),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 aboard the DMSP F-16 satellite and recently flown aboard DMSP F-17 and F-18 satellites.

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

The SSM/I sensor executes a 45º conical scan of the Earth's surface from nadir. This gives a nominal incidence (zenith) angle of 53.1º to the Earth's surface from the nominal orbit. Only part of the possible 360º scan in azimuth is used to collect data. The active azimuth scan angle is 102.4º is ahead of the S/C for an afternoon ascending orbit and behind the S/C for a morning ascending orbit.

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 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

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

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

SENSITIVITY -

CALIBRATION Hot load target Two microwave reference target. Tb = Tc + (Th – Tc )* (Vb – Vc/Vh – Vc) Inst Err = Tb - Tvar

APPLICATIONS SDR- EDR

REFERENCES J. P. Hollinger, J. L. Peirce, G. A. Poe, “SSM/I USER’S GUIDE “ 14 SEPTEMBER 1987 Chris Allen “EECS 823 CLASS NOTES” 10 DECEMBER missions/d/dmsp-block-5d#references