MIRAS reference radiometer: a fully polarimetric noise injection radiometer

Colliander, Andreas; Tauriainen, S.; Auer, T.; Kainulainen, Juha; Uusitalo, J.; Toikka, M.; Hallikainen, M.

doi:10.1109/tgrs.2004.840667

Cited by 38 publications

(15 citation statements)

References 7 publications

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“…In this mode, the radiometer is measuring the brightness temperature of a fixed region of the sky near the galactic pole to avoid influence from the Galactic emission. The known sky brightness temperature at L-band is then used to calibrate several MIRAS parameters such as antenna pattern errors, PMS gains and the reference radiometer coefficients [6].…”

Section: External Calibrationmentioning

confidence: 99%

SMOS brightness temperature measurements and end-to-end calibration

Torres¹,

Corbella²,

Duffo³

et al. 2011

2011 IEEE International Geoscience and Remote Sensing Symposium

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SMOS is the acronym for the Soil Moisture and Ocean Salinity mission by the European Space Agency (ESA) [1]. Its single payload, the Microwave Imaging Radiometer using Aperture Synthesis (MIRAS), was launched in November 2009. After a six months Commissioning Phase SMOS entered in operational mode in May 2010. Since then SMOS has been delivering a large amount of data to successfully produce the first relevant scientific results. In order to provide accurate measurements, MIRAS requires a complex multi-step calibration procedure that was successfully tested both during pre-flight ground tests and Commissioning Phase activities. Additionally, an assessment of SMOS system performance in terms of short and long term stability, radiometric sensitivity and radiometric accuracy was also produced. In this context, this work is devoted to provide a high level overview of MIRAS calibration scheme by focusing on the rationale behind it.Peer ReviewedPostprint (published version

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Section: External Calibrationmentioning

confidence: 99%

SMOS brightness temperature measurements and end-to-end calibration

Torres¹,

Corbella²,

Duffo³

et al. 2011

2011 IEEE International Geoscience and Remote Sensing Symposium

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“…The NIR consists of two independent receivers connected to a dual-polarization antenna and to an internal noise injection circuitry, so that all four Stokes parameters can be measured using the correlator matrix [4]. Its operation is based on an internal noise source which is used to balance the input signal to the receivers.…”

Section: Instrument Raw Datamentioning

confidence: 99%

“…However, in the NIR the so-called one-point calibration is applied. This means that the level of the noise injection is determined with one target, after which the antenna temperature can be determined using the physical temperature of the NIR and the ancillary data described in Section II [4]. In orbit, the space background radiation is foreseen to be used as the calibration target for NIR.…”

Section: Brightness Temperature In Antenna Reference Planesmentioning

confidence: 99%

MIRAS end-to-end calibration: application to SMOS L1 processor

Corbella

Torres

Camps

et al. 2005

IEEE Trans. Geosci. Remote Sensing

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100

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Abstract-End-to-end calibration of the Microwave Imaging Radiometer by Aperture Synthesis (MIRAS) radiometer refers to processing the measured raw data up to dual-polarization brightness temperature maps over the earth's surface, which is the level 1 product of the Soil Moisture and Ocean Salinity (SMOS) mission. The process starts with a self-correction of comparators offset and quadrature error and is followed by the calibration procedure itself. This one is based on periodically injecting correlated and uncorrelated noise to all receivers in order to measure their relevant parameters, which are then used to correct the raw data. This can deal with most of the errors associated with the receivers but does not correct for antenna errors, which must be included in the image reconstruction algorithm. Relative S-parameters of the noise injection network and of the input switch are needed as additional data, whereas the whole process is independent of the exact value of the noise source power and of the distribution network physical temperature. On the other hand, the approach relies on having at least one very well-calibrated reference receiver, which is implemented as a noise injection radiometer. The result is the calibrated visibility function, which is inverted by the image reconstruction algorithm to get the brightness temperature as a function of the director cosines at the antenna reference plane. The final step is a coordinate rotation to obtain the horizontal and vertical brightness temperature maps over the earth. The procedures presented are validated using a complete SMOS simulator previously developed by the authors.

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“…A similar study was presented at IGARSS'04 [4] for the prototype of the NIR [5]. Novelty of this study, compared to the previous, lies on the facts that (1) it is based on more thorough temperature cycling, (2) it includes also the antenna and (3) the analysed model (EM) is representative to Flight Model of NIR.…”

Section: Introductionmentioning

confidence: 93%

Temperature variation compensation in engineering model of MIRAS reference radiometer

Colliander¹,

Suomela²,

Ruokokoski³

et al.

Proceedings. 2005 IEEE International Geoscience and Remote Sensing Symposium, 2005. IGARSS '05.

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We present a compensation method for the temperature variation of the reference radiometer (NIR) of the MIRAS instrument on the SMOS mission. A similar study done for the prototype of the reference radiometer has been reported at IGARSS'04. Novelty of this study, compared to the previous, lies on the facts that (1) it is based on more thorough temperature cycling, (2) it includes also the antenna and (3) the analysed model (EM) is representative to Flight Model of NIR. We present a thermal model for the NIR front-end and noise source that further improves the stability so that the desired performance, which arises from the requirements for the measurement of soil moisture and ocean salinity, can be met.

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MIRAS reference radiometer: a fully polarimetric noise injection radiometer

Cited by 38 publications

References 7 publications

SMOS brightness temperature measurements and end-to-end calibration

SMOS brightness temperature measurements and end-to-end calibration

MIRAS end-to-end calibration: application to SMOS L1 processor

Temperature variation compensation in engineering model of MIRAS reference radiometer

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