Dynamic range and linearity trade-off in detectors for interferometric radiometers

Abstract-This paper reviews the relative calibration of an interferometric radiometer taking into account the experimental results of the first batch of receivers developed in the frame of the European Space Agency's Soil Moisture and Ocean Salinity mission. Measurements show state-of-the-art baseline performance as long as the system is capable of correcting the effect of orbital temperature swing. A method to validate internal calibration during in-orbit deep-sky views and to correct linearity errors is also presented.

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“…1) by means of the socalled two-level four-point method [6], [7]. HOT and WARM injected temperatures are defined at the C port as…”

Section: A Two-level Four-point Calibrationmentioning

confidence: 99%

Denormalization of visibilities for in-orbit calibration of interferometric radiometers

Torres

Corbella²,

Camps³

et al.

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

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“…In addition, the predetection circuit of each receiver includes a variable attenuator with two attenuation levels, enabling a four-point calibration of the receiver offset as described in [7] and [8]. CAS takes advantage of the distributed noise generation method introduced and described in [10].…”

Section: Operational Principlementioning

confidence: 99%

“…Errors in the LICEF PMS measurements (see the Appendix) consist of the linearity error of ν k , the uncertainty of T SYS,C , and the accuracy of the attenuator L 1 [8]. For the sake of simplicity, L 1 and ν kn are considered ideal in all cases, as are the first measurements of T C sysN using NIR.…”

Section: A Propagation Of Amplitude Errormentioning

confidence: 99%

SMOS Calibration Subsystem

Lemmetyinen¹,

Uusitalo

Kainulainen³

et al. 2007

IEEE Trans. Geosci. Remote Sensing

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Interferometric radiometry is a novel concept in remote sensing that is also presenting particular challenges for calibration methods. In this paper, we describe the calibration subsystem (CAS) developed for the Microwave Imaging Radiometer using Aperture Synthesis (MIRAS) interferometer of the Soil Moisture and Ocean Salinity (SMOS) satellite. CAS is important for the overall performance of the payload as it calibrates out the differences between the multiple receivers of MIRAS. SMOS is in the final phase of development and is due to launch in 2008.

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“…The radio-frequency (RF) part amplifies and filters the input signal to 1404-1423 MHz. The mixer shifts this band to an intermediate frequency at [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] MHz using a local oscillator common to all receivers. Two intermediate frequency (IF) output signals are produced, namely the in-phase and quadrature components.…”

Section: Instrument Raw Datamentioning

confidence: 99%

“…For the special case of and , (4) and (6) reduce to (7) (8) from which the quadrature error of any receiver is easily retrieved (9) Once the quadrature error is known, comes after solving (4) (10) where is the so-called quadrature-corrected normalized correlation (11) where is the normalized complex correlation and and depend exclusively on the quadrature error of receivers and (12) where (13) and the quadrature error is given by (9). The quadrature corrected normalized correlation is continuously computed from the measurements , , and .…”

Section: A Correlator Offset and Quadrature Correctionsmentioning

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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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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Dynamic range and linearity trade-off in detectors for interferometric radiometers

Cited by 13 publications

References 1 publication

Denormalization of visibilities for in-orbit calibration of interferometric radiometers

Denormalization of visibilities for in-orbit calibration of interferometric radiometers

SMOS Calibration Subsystem

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

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