scholarly journals Quantifying the calibration uncertainty attributable to thermocouple inhomogeneity

2013 ◽  
Author(s):  
K. D. Hill ◽  
D. J. Gee
Keyword(s):  
Calibration Uncertainty ◽  
Thermocouple Inhomogeneity

scholarly journals Impulse Conditioner for Verification (Calibration) of Digital Electronic Stopwatch-Timers

2020 ◽  
pp. 27-29
Author(s):  
S. O. Grudzinsky ◽  
V. N. Odnoralov
Keyword(s):  
Frequency Spectrum ◽  
Quartz Resonator ◽  
Control Procedure ◽  
New Device ◽  
Calibration Uncertainty ◽  
Resonator Frequency ◽  
Real Value

New upgraded device for digital electronic stopwatch-timers calibration has been developed and researched. Real value of quartz resonator frequency has been measured. New device provides the stopwatch-timers calibration of various models for any frequency spectrum. The device enables to shorten the time for calibration and to reduce the calibration uncertainty. Control procedure for main digital stopwatch-timers characteristics has been described. The procedure doesn’t contain any handmade operations depended on operator reaction. Already there are no necessity to use any mechanic device for start/stop of stopwatch-timers.

scholarly journals Absolute calibration method for frequency-modulated continuous wave (FMCW) cloud radars based on corner reflectors

2020 ◽  
Vol 13 (12) ◽  
pp. 6853-6875
Author(s):  
Felipe Toledo ◽  
Julien Delanoë ◽  
Martial Haeffelin ◽  
Jean-Charles Dupont ◽  
Susana Jorquera ◽  
...  
Keyword(s):  
Field Experiments ◽  
Continuous Wave ◽  
Intermediate Frequency ◽  
Absolute Calibration ◽  
Experimental Setup ◽  
Cloud Radar ◽  
Calibration Uncertainty ◽  
Radar Calibration ◽  
The Impact ◽  
Uncertainty Source

Abstract. This article presents a new cloud radar calibration methodology using solid reference reflectors mounted on masts, developed during two field experiments held in 2018 and 2019 at the Site Instrumental de Recherche par Télédétection Atmosphérique (SIRTA) atmospheric observatory, located in Palaiseau, France, in the framework of the Aerosol Clouds Trace gases Research InfraStructure version 2 (ACTRIS-2) research and innovation program. The experimental setup includes 10 and 20 cm triangular trihedral targets installed at the top of 10 and 20 m masts, respectively. The 10 cm target is mounted on a pan-tilt motor at the top of the 10 m mast to precisely align its boresight with the radar beam. Sources of calibration bias and uncertainty are identified and quantified. Specifically, this work assesses the impact of receiver compression, temperature variations inside the radar, frequency-dependent losses in the receiver's intermediate frequency (IF), clutter and experimental setup misalignment. Setup misalignment is a source of bias, previously undocumented in the literature, that can have an impact of the order of tenths of a decibel in calibration retrievals of W-band radars. A detailed analysis enabled the quantification of the importance of each uncertainty source to the final cloud radar calibration uncertainty. The dominant uncertainty source comes from the uncharacterized reference target which reached 2 dB. Additionally, the analysis revealed that our 20 m mast setup with an approximate alignment approach is preferred to the 10 m mast setup with the motor-driven alignment system. The calibration uncertainty associated with signal-to-clutter ratio of the former is 10 times smaller than for the latter. Following the proposed methodology, it is possible to reduce the added contribution from all uncertainty terms, excluding the target characterization, down to 0.4 dB. Therefore, this procedure should enable the achievement of calibration uncertainties under 1 dB when characterized reflectors are available. Cloud radar calibration results are found to be repeatable when comparing results from a total of 18 independent tests. Once calibrated, the cloud radar provides valid reflectivity values when sampling midtropospheric clouds. Thus, we conclude that the method is repeatable and robust, and that the uncertainties are precisely characterized. The method can be implemented under different configurations as long as the proposed principles are respected. It could be extended to reference reflectors held by other lifting devices such as tethered balloons or unmanned aerial vehicles.

scholarly journals Calibration Uncertainty of Flowmeters for Liquids by Using Subtraction Method

2012 ◽  
Vol 78 (788) ◽  
pp. 821-836
Author(s):  
Takashi SHIMADA ◽  
Ryouji DOIHARA ◽  
Yoshiya TERAO ◽  
Masaki TAKAMOTO
Keyword(s):  
Subtraction Method ◽  
Calibration Uncertainty

Accuracy of Satellite Land Surface Reflectance Determination

1991 ◽  
Vol 30 (7) ◽  
pp. 960-972 ◽  
Author(s):  
O. Arino ◽  
G. Dedieu ◽  
P. Y. Deschamps
Keyword(s):  
Land Surface ◽  
Surface Albedo ◽  
Maximum Error ◽  
Surface Reflectance ◽  
Relative Uncertainty ◽  
Calibration Uncertainty ◽  
Maximum Bias ◽  
Calibration Accuracy ◽  
The Difference

Abstract An accuracy budget of the surface reflectance determination from Meteosat geostationary satellite data is performed. Error analysis allows identification of three main problems: calibration uncertainty of the Meteosat instrument, atmospheric corrections, and surface effects (spectral and directional). Calibration accuracy is 10%, leading to a 10% relative uncertainty on reflectance. Spectral effects of the surface lead to a maximum bias of 0.01 for a vegetated surface as sensed by Meteosat, while directional effects can lead to a bias of 0.035 between two measurements taken at two different sun zenith and azimuth angles at the same view angle over savannas. The maximum error due to the atmosphere is estimated to be of the order of 0.03 in reflectance for a surface reflectance of 0.40 and 0.01 for, a surface reflectance of 0.10. Validation with in situ measurement is within the expected error over savanna. But the difference is still high over the southwest France site of HAPEX-MOBILHY, certainly due to the joint spectral and directional errors. Comparisons with surface albedo maps from literature show the same spatial and spatial evolutions with a better spatial and temporal determination in our results.

Dose calibration uncertainty and plan-specific dose calibration for IMRT QA

2018 ◽  
Vol 5 (1) ◽  
pp. 015024
Author(s):  
Wei Luo ◽  
Yinnan Meng ◽  
Stephen Brock Westlund
Keyword(s):  
Imrt Qa ◽  
Calibration Uncertainty

Calibration uncertainty of MEMS thermopile imagers for quantitative temperature measurement

2021 ◽  
pp. 103978
Author(s):  
Vitor F. Paes ◽  
Barbara A. Mueller ◽  
Pedro B. Costa ◽  
Rafael A.M. Ferreira ◽  
Matheus P. Porto
Keyword(s):  
Temperature Measurement ◽  
Calibration Uncertainty

scholarly journals Three years of Sun-as-a-star radial-velocity observations on the approach to solar minimum

2019 ◽  
Vol 487 (1) ◽  
pp. 1082-1100 ◽  
Author(s):  
A Collier Cameron ◽  
A Mortier ◽  
D Phillips ◽  
X Dumusque ◽  
R D Haywood ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Zero Point ◽  
Spatially Resolved ◽  
Solar Observations ◽  
Bayesian Mixture Model ◽  
Mixture Model Approach ◽  
Calibration Uncertainty ◽  
Bayesian Mixture ◽  
Solar Type ◽  
Line Asymmetry

Abstract The time-variable velocity fields of solar-type stars limit the precision of radial-velocity determinations of their planets’ masses, obstructing detection of Earth twins. Since 2015 July, we have been monitoring disc-integrated sunlight in daytime using a purpose-built solar telescope and fibre feed to the HARPS-N stellar radial-velocity spectrometer. We present and analyse the solar radial-velocity measurements and cross-correlation function (CCF) parameters obtained in the first 3 yr of observation, interpreting them in the context of spatially resolved solar observations. We describe a Bayesian mixture-model approach to automated data-quality monitoring. We provide dynamical and daily differential-extinction corrections to place the radial velocities in the heliocentric reference frame, and the CCF shape parameters in the sidereal frame. We achieve a photon-noise-limited radial-velocity precision better than 0.43 m s−1 per 5-min observation. The day-to-day precision is limited by zero-point calibration uncertainty with an RMS scatter of about 0.4 m s−1. We find significant signals from granulation and solar activity. Within a day, granulation noise dominates, with an amplitude of about 0.4 m s−1 and an autocorrelation half-life of 15 min. On longer time-scales, activity dominates. Sunspot groups broaden the CCF as they cross the solar disc. Facular regions temporarily reduce the intrinsic asymmetry of the CCF. The radial-velocity increase that accompanies an active-region passage has a typical amplitude of 5 m s−1 and is correlated with the line asymmetry, but leads it by 3 d. Spectral line-shape variability thus shows promise as a proxy for recovering the true radial velocity.

Microfabricated Shear-Stress Sensors, Part 3: Reducing Calibration Uncertainty

AIAA Journal ◽  
2002 ◽  
Vol 40 (8) ◽  
pp. 1582-1588 ◽  
Author(s):  
Mehul P. Patel ◽  
Eli Reshotko ◽  
Daniel Hyman
Keyword(s):  
Shear Stress ◽  
Stress Sensors ◽  
Calibration Uncertainty ◽  
Shear Stress Sensors
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