Development and Calibration of SMOS Reference Radiometer

Colliander, Andreas; Ruokokoski, L.; Suomela, J.; Veijola, Katriina; Kettunen, J.; Kangas, V.; Aalto, Aleksi; Levander, M.; Greus, H.; Hallikainen, M.; Lahtinen, J.

doi:10.1109/tgrs.2007.894055

Cited by 46 publications

(49 citation statements)

References 13 publications

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“…Each antenna is, in turn, connected to a corresponding L-band low-noise receiver called "LIghtweight Cost-Effective Front-end" (LICEF), each one having an input switch to select one of two orthogonal polarizations. Three of the antennas in the hub are not assigned to LICEF's, but connected instead to full-polarimetric noise-injection radiometers (NIRs) used as reference receivers [12]. To perform internal calibration, a noise distribution network (NDN) and internal noise sources are also included in the instrument [13].…”

Section: Instrumentmentioning

confidence: 99%

“…To perform internal calibration, a noise distribution network (NDN) and internal noise sources are also included in the instrument [13]. A summary of the main components is as follows: 1) 69 small antennas (66 in LICEF and 3 in NIR); 2) 72 front ends (66 for LICEF and 6 for the two channels of the three NIRs); 3) 2346 baselines (2145 between LICEFs, 198 between NIR and LICEF, and 3 between NIRs); 4) 10 noise sources with associated distribution network [three per arm (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12) and one in the HUB (1-18)]; 5) 121 temperature sensors (72 in LICEFs, 31 in calibration system, and 18 in NIR). This hardware produces the following signals: 1) 72 power measurement system (PMS) voltages; 2) 2556 × 2 digital correlator counts (real and imaginary);…”

Section: Instrumentmentioning

confidence: 99%

“…Two levels of noise (named "Hot" and "Warm") are sequentially injected to the receivers' inputs as well as to the NIR's. The noise temperatures at the NIR's inputs are retrieved from their outputs (fraction of Dicke cycle) using factory calibration parameters and the procedures described in [12]. These temperatures are transferred to all LICEF's inputs using the S-parameters of the NDN, independently characterized by the Helsinky University of Technology [13].…”

Section: Internal-calibration Assessmentmentioning

confidence: 99%

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On-Ground Characterization of the SMOS Payload

Corbella

Torres

Duffo

et al. 2009

IEEE Trans. Geosci. Remote Sensing

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Abstract-The on-ground characterization of the synthetic aperture radiometer onboard the Soil Moisture and Ocean Salinity mission is described. Characterization includes basic functionality, internal calibration, thermal cycling, response to point and flat sources, self-radio-frequency interference, and others. The description of the different tests performed as well as the detailed results are provided. The results show that the instrument is very stable and has all gains and offsets consistent with the ones obtained at subsystem level. On the other hand, the phase of the visibility has a larger variation with temperature than expected, a small signal leakage from the local oscillators is present, and a small interference from the X-band transmitter during short periods of time has been detected. The implementation of internal-calibration procedures, along with the accurate thermal characterization performed, have been used to produce highly accurate brightness-temperature values well within specifications.Index Terms-Calibration and characterization, interferometric aperture synthesis, microwave radiometry.

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Section: Instrumentmentioning

confidence: 99%

Section: Instrumentmentioning

confidence: 99%

Section: Internal-calibration Assessmentmentioning

confidence: 99%

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On-Ground Characterization of the SMOS Payload

Corbella

Torres

Duffo

et al. 2009

IEEE Trans. Geosci. Remote Sensing

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“…The basis of the SMOS brightness temperature level is the measurements performed with the so-called zero-baselines [3]; SMOS employs an interferometric measurement technique which forms a brightness temperature image from several baselines constructed by combination of multiple receivers in an array; zero-length baseline defines the overall brightness temperature level. The basis of the Aquarius brightness temperature level is resolved from the brightness temperature simulator combined with ancillary data such as antenna patterns and environmental models [4].…”

Section: Introductionmentioning

confidence: 99%

Synthesizing SMOS zero-baselines with Aquarius brightness temperature simulator

Colliander

Dinnat

Vine

et al. 2012

2012 IEEE International Geoscience and Remote Sensing Symposium

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“…[2][3][4][5] In these receivers there are two main sources of nonlinear behavior: detectors and low-noise amplifiers ͑LNAs͒. Linearity of astronomical detectors is considered an important issue.…”

Section: Introductionmentioning

confidence: 99%

Simple nonlinearity evaluation and modeling of low-noise amplifiers with application to radio astronomy receivers

Casas

Pascual

Fuente

et al. 2010

Review of Scientific Instruments

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Controlling a telescope chopping secondary mirror assembly using a signal deconvolution technique Rev. Sci. Instrum. 74, 3802 (2003) A wideband lag correlator for heterodyne spectroscopy of broad astronomical and atmospheric spectral lines Rev. Sci. Instrum. 72, 1531 (2001 A medium-frequency interferometer for studying auroral radio emissions Rev. Sci. Instrum. 71, 3200 (2000) Implementation of a photonic automatic gain control system for correcting gain variations in the Green Bank Telescope fiber optic system Rev. Sci. Instrum. 71, 3196 (2000) The Mt. Fuji submillimeter-wave telescope Rev. Sci. Instrum. 71, 2895(2000 Additional information on Rev. Sci. Instrum. This paper describes a comparative nonlinear analysis of low-noise amplifiers ͑LNAs͒ under different stimuli for use in astronomical applications. Wide-band Gaussian-noise input signals, together with the high values of gain required, make that figures of merit, such as the 1 dB compression ͑1 dBc͒ point of amplifiers, become crucial in the design process of radiometric receivers in order to guarantee the linearity in their nominal operation. The typical method to obtain the 1 dBc point is by using single-tone excitation signals to get the nonlinear amplitude to amplitude ͑AM-AM͒ characteristic but, as will be shown in the paper, in radiometers, the nature of the wide-band Gaussian-noise excitation signals makes the amplifiers present higher nonlinearity than when using single tone excitation signals. Therefore, in order to analyze the suitability of the LNA's nominal operation, the 1 dBc point has to be obtained, but using realistic excitation signals. In this work, an analytical study of compression effects in amplifiers due to excitation signals composed of several tones is reported. Moreover, LNA nonlinear characteristics, as AM-AM, total distortion, and power to distortion ratio, have been obtained by simulation and measurement with wide-band Gaussian-noise excitation signals. This kind of signal can be considered as a limit case of a multitone signal, when the number of tones is very high. The work is illustrated by means of the extraction of realistic nonlinear characteristics, through simulation and measurement, of a 31 GHz back-end module LNA used in the radiometer of the QUIJOTE ͑Q U I JOint TEnerife͒ CMB experiment.

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Development and Calibration of SMOS Reference Radiometer

Cited by 46 publications

References 13 publications

On-Ground Characterization of the SMOS Payload

On-Ground Characterization of the SMOS Payload

Synthesizing SMOS zero-baselines with Aquarius brightness temperature simulator

Simple nonlinearity evaluation and modeling of low-noise amplifiers with application to radio astronomy receivers

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