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... > Instruments > Earth Remote Sensing Instruments > Passive Remote Sensing > Spectrometers/Radiometers > Radiometers > SMR

Preferred term

SMR  

Definition

  • The Odin SMR (Sub-Millimeter Radiometer) instrument continues to produce profiles of chemical species relevant to understanding the middle and upper atmosphere. The long-term observation of stratospheric ozone can be useful for trend analysis of chemical ozone loss. SMR is a Swedish instrument in cooperation with Finland (119 GHz channel), and France, provision of the AOS (Acousto-Optic Spectrometer) detector. SMR is a passive microwave limb sounder with one receiver at a wavelength of 3 mm and additional four bands within the submillimeter range (0.5 - 1.0 mm) corresponding to a frequency range of 486 - 580 GHz. Antenna reflector type: offset Gregorian telescope [off-axis system, 1.1 m diameter, surface roughness: 10 µm rms, material: carbon fiber reinforced plastic (CFRP)]. SMR is used in the astronomy as well as in the atmospheric research mission to detect molecular transitions. The signal coming from the telescope is routed to the receivers, split and filtered by optics consisting of combinations of mirrors, grids and meshes. Diplexers and sideband filters are based on tunable polarizing Michelson interferometers. The SMR telescope is being equipped with a very flexible cryogenic sub-mm receiver package (cooling to -175º C). The frequency range of 541-581 GHz is covered by three tuneable Schottky mixers and a fourth Schottky mixer covers the band 486-504 GHz. A 119 GHz fix-tuned HEMT preamplifier has been installed to allow very sensitive searches for interstellar O2. All receivers are operated in single-sideband mode. The five single sideband heterodyne receivers in SMR are continuously switched between a reference source of known signal strength and the signal from the telescope (Dicke switch). The telescope is periodically targeted towards well-known celestial objects. These procedures ensure both stability and good calibration. Spectral lines: The SMR instrument covers transitions of aeronomical interest from the following molecules: ClO, CO, NO2, N2O, H2O2, HO2, H2O, H218O, NO, HNO3, O3, and O2; and atomic and molecular transitions of astrophysical interest from: Cl, H218O, H2O, H2S, NH3, H2CO, O2, CS, 13CO, H2CS, SO, SO2 Type Single sideband heterodyne receivers (use of InP material), Frequencies 118.25 - 119.25 GHz, 486.1 - 503.9 GHz, 541 - 580.4 GHz Bandwidth 100 MHz to 1 GHz Resolution 0.1 MHz to 1 MHz Sensitivity 1 K in 1 MHz with S/N = 5 after 15 minutes Mixers Cooled Schottky mixers Local Oscillators LO based on Gunn diodes and frequency multipliers LNA Cooled HEMT low noise amplifiers Spectrometers two hybrid autocorrelators and one AOS (Acousto-Optic Spectrometer) (en)

Broader concept

Change note

  • 2018-07-05 14:14:46.0 [mmorahan] Insert Concept add broader relation (SMR [c143ee20-1d14-4003-9043-f028c19f0265,367783] - Radiometers [5b753e40-b3f1-426a-8d92-ffee1d675468,347283]);
  • 2018-07-05 14:16:57.0 [mmorahan] insert AltLabel (id: null category: primary text: Sub-Millimeter Radiometer language code: en); insert Definition (id: null text: The Odin SMR (Sub-Millimeter Radiometer) instrument continues to produce profiles of chemical species relevant to understanding the middle and upper atmosphere. The long-term observation of stratospheric ozone can be useful for trend analysis of chemical ozone loss. SMR is a Swedish instrument in cooperation with Finland (119 GHz channel), and France, provision of the AOS (Acousto-Optic Spectrometer) detector. SMR is a passive microwave limb sounder with one receiver at a wavelength of 3 mm and additional four bands within the submillimeter range (0.5 - 1.0 mm) corresponding to a frequency range of 486 - 580 GHz. Antenna reflector type: offset Gregorian telescope [off-axis system, 1.1 m diameter, surface roughness: 10 µm rms, material: carbon fiber reinforced plastic (CFRP)]. SMR is used in the astronomy as well as in the atmospheric research mission to detect molecular transitions. The signal coming from the telescope is routed to the receivers, split and filtered by optics consisting of combinations of mirrors, grids and meshes. Diplexers and sideband filters are based on tunable polarizing Michelson interferometers. The SMR telescope is being equipped with a very flexible cryogenic sub-mm receiver package (cooling to -175º C). The frequency range of 541-581 GHz is covered by three tuneable Schottky mixers and a fourth Schottky mixer covers the band 486-504 GHz. A 119 GHz fix-tuned HEMT preamplifier has been installed to allow very sensitive searches for interstellar O2. All receivers are operated in single-sideband mode. The five single sideband heterodyne receivers in SMR are continuously switched between a reference source of known signal strength and the signal from the telescope (Dicke switch). The telescope is periodically targeted towards well-known celestial objects. These procedures ensure both stability and good calibration. Spectral lines: The SMR instrument covers transitions of aeronomical interest from the following molecules: ClO, CO, NO2, N2O, H2O2, HO2, H2O, H218O, NO, HNO3, O3, and O2; and atomic and molecular transitions of astrophysical interest from: Cl, H218O, H2O, H2S, NH3, H2CO, O2, CS, 13CO, H2CS, SO, SO2 Type Single sideband heterodyne receivers (use of InP material), Frequencies 118.25 - 119.25 GHz, 486.1 - 503.9 GHz, 541 - 580.4 GHz Bandwidth 100 MHz to 1 GHz Resolution 0.1 MHz to 1 MHz Sensitivity 1 K in 1 MHz with S/N = 5 after 15 minutes Mixers Cooled Schottky mixers Local Oscillators LO based on Gunn diodes and frequency multipliers LNA Cooled HEMT low noise amplifiers Spectrometers two hybrid autocorrelators and one AOS (Acousto-Optic Spectrometer) language code: en);
  • 2019-02-22 08:41:13.0 [mmorahan] insert WeightedRelation (id: null related concept uuid: 1f7c6ae3-d38e-42b7-a874-60298b0fcfa1 relationship type: null relationship value: null generated by: null);

URI

https://gcmd.earthdata.nasa.gov/kms/concept/c143ee20-1d14-4003-9043-f028c19f0265

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