Calibration procedure of a microwave total-power radiometer

Al-Ansari, K.; García, Pedro López; Riera, José Manuel; Benarroch, Ana; Fernández, Diego; Fernández, Lara P.

doi:10.1109/7260.989862

Cited by 11 publications

(6 citation statements)

References 2 publications

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“…This assumption has also been considered in the calibration of other radiometer systems [7], [8]. While there are undoubtedly secondary effects, this is an acceptable starting point before considering other contributing factors.…”

Section: B Gain Tied To Receiver Temperaturesmentioning

confidence: 99%

WindSat on-orbit warm load calibration

Twarog

Purdy²,

Gaiser

et al. 2006

IEEE Trans. Geosci. Remote Sensing

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Abstract-Postlaunch calibration of the WindSat polarimetric microwave radiometer indicates the presence of thermal gradients across the calibration warm load during some portions of the year. These gradients are caused by reflected solar illumination or eclipse and increase total calibration errors. This paper describes the WindSat warm load and presents the measured on-orbit data which clearly illustrate the anomalous responses seen in the warm load calibration data. Detailed thermal modeling predictions of the WindSat on-orbit performance are presented along with the satellite orbital geometry model with solar inputs in order to explain the physical causes of the thermal gradients. To reduce the resultant calibration errors during periods of anomalous warm load behavior, a correction algorithm was developed which uses the physical temperatures of the gain stages in the receiver electronics to calculate an effective gain. This calibration algorithm is described, and its performance and expected accuracy are examined.

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Section: B Gain Tied To Receiver Temperaturesmentioning

confidence: 99%

WindSat on-orbit warm load calibration

Twarog

Purdy²,

Gaiser

et al. 2006

IEEE Trans. Geosci. Remote Sensing

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“…The sky tipping curve calibration method involves recording a radiometric profile of the sky temperature as a function of elevation angle and fitting it to a theoretical curve [15,16]. For an upwards viewing radiometer, operating in the atmospheric windows, the radiative transfer equation of down-welling brightness temperature can be approximated by:-…”

Section: Radiometric Calibrationmentioning

confidence: 99%

“…Consequently, the calibration of the radiometer mode is done in two stages. Short term fluctuations in the gain of the IF stage amplifiers are corrected through the use of noise adding circuit [14], whilst the absolute calibration, including the front end components, is done using a tipping curve method which fits measured data to the known temperature versus elevation profile of the atmosphere [15,16].…”

Section: Radiometric Calibrationmentioning

confidence: 99%

A 94 GHz dual-mode imaging radarometer for remote sensing

Robertson

Macfarlane

2006

SPIE Proceedings

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We report on the continued development of our 94GHz dual-mode radar/radiometric imager, AVTIS. To date we have concentrated on refining the radar mode and can now acquire state-of-the-art long range, high resolution radar images. More recently we have worked to improve and integrate the radiometric mode, to complete the dual-mode functionality. One notable problem of the monostatic architecture is that of radar transmitter leakage via the circulator/antenna assembly, even with the transmitter signal heavily attenuated. A related issue is the high level of AM noise in the local oscillator signal due to the IMPATT multipliers and power amplifiers used. This far-off-the-carrier noise, in combination with the leakage, desensitises the receiver and raises the noise floor to give a receiver noise temperature of approximately 6000K. This yields a thermal resolution of 2K in 4ms that is considered adequate for the intended volcanological application. In comparison, tests with a high power Schottky diode multiplier chain as the LO source has yielded a noise temperature of 750K in a separate radiometer. Thermal calibration is also of concern and we have implemented an IF noise adding circuit in which the radiometer alternates between the scene and hot and cold IF noise references. This accounts for dominant receiver fluctuations in the IF amplifiers but sky tipping curves are used to calibrate the overall response. Whilst the radar is already capable of producing high resolution topographic maps with surface reflectivity overlaid, it is hoped that co-aligned radiometric brightness temperature data will lead to a better understanding of the emissivity and surface roughness of the terrain being surveyed.

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“…Because of the disadvantage of not having a thermal insulation box, a method of radiometric calibration without a thermal insulation box using a physical temperature sensor was introduced in 2002 [3]. Radiometric calibration using physical temperature monitoring could be a good candidate for UAV (Unmanned Aerial Vehicle) applications because of their limited weight and power [4]. Radiometric calibration ability using physical temperature sensors was shown in previous research [3], [5], [6].…”

Section: Introductionmentioning

confidence: 97%

Temperature Drift Compensation Using Multiple Linear Regression for a <inline-formula> <tex-math notation="LaTeX">$W$ </tex-math></inline-formula>-Band Total Power Radiometer

Moon

Kim

2015

IEEE Sensors J.

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Calibration of radiometer systems using physical temperature monitoring have been developed to compensate the temperature drift. Because calibration standards are not necessary to obtain the system response characteristic, it is good candidate for applications of the limited weight and power. Besides, the estimation of the calibration accuracy could be improved by stable condition based on multiple temperature sensors. In this paper, we analyzed the estimated calibration accuracy under indoor environmental conditions using multiple temperature sensors for a W -band direct detection radiometer system. The method was implemented to obtain the radiometer calibration coefficient based on the relationship between the temperature sensors at multiple positions and the gain variation. The estimated accuracy of the brightness temperature was determined by the temperature sensor response with respect to the receiver gain variation under environmental conditions. The distributed temperature sensors were considered for optimum regression of the radiometer gain variation in a heated environment.

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Calibration procedure of a microwave total-power radiometer

Cited by 11 publications

References 2 publications

WindSat on-orbit warm load calibration

WindSat on-orbit warm load calibration

A 94 GHz dual-mode imaging radarometer for remote sensing

Temperature Drift Compensation Using Multiple Linear Regression for a <inline-formula> <tex-math notation="LaTeX">$W$ </tex-math></inline-formula>-Band Total Power Radiometer

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