scholarly journals Instrument Development: Chinese Radiometric Benchmark of Reflected Solar Band Based on Space Cryogenic Absolute Radiometer

2020 ◽  
Vol 12 (17) ◽  
pp. 2856
Author(s):  
Xin Ye ◽  
Xiaolong Yi ◽  
Chao Lin ◽  
Wei Fang ◽  
Kai Wang ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Measurement Accuracy ◽  
Signal To Noise Ratio ◽  
Imaging Spectrometer ◽  
Term Stability ◽  
Long Term Stability ◽  
Remote Sensors ◽  
Cross Calibration ◽  
Transfer Chain

Low uncertainty and long-term stability remote data are urgently needed for researching climate and meteorology variability and trends. Meeting these requirements is difficult with in-orbit calibration accuracy due to the lack of radiometric satellite benchmark. The radiometric benchmark on the reflected solar band has been under development since 2015 to overcome the on-board traceability problem of hyperspectral remote sensing satellites. This paper introduces the development progress of the Chinese radiometric benchmark of the reflected solar band based on the Space Cryogenic Absolute Radiometer (SCAR). The goal of the SCAR is to calibrate the Earth–Moon Imaging Spectrometer (EMIS) on-satellite using the benchmark transfer chain (BTC) and to transfer the traceable radiometric scale to other remote sensors via cross-calibration. The SCAR, which is an electrical substitution absolute radiometer and works at 20 K, is used to realize highly accurate radiometry with an uncertainty level that is lower than 0.03%. The EMIS, which is used to measure the spectrum radiance on the reflected solar band, is designed to optimize the signal-to-noise ratio and polarization. The radiometric scale of the SCAR is converted and transferred to the EMIS by the BTC to improve the measurement accuracy and long-term stability. The payload of the radiometric benchmark on the reflected solar band has been under development since 2018. The investigation results provide the theoretical and experimental basis for the development of the reflected solar band benchmark payload. It is important to improve the measurement accuracy and long-term stability of space remote sensing and provide key data for climate change and earth radiation studies.

Results of experimental tests for the evaluation of the signal-to-noise ratio, short-term stability, linearity in the time axis, and long-term stability of the GPR signal - according to COST Action TU1208 guidelines

2020 ◽  
Author(s):  
Milan Vrtunski ◽  
Lara Pajewski ◽  
Aleksandar Ristić ◽  
Željko Bugarinović ◽  
Miro Govedarica
Keyword(s):  
Ground Penetrating Radar ◽  
Signal To Noise Ratio ◽  
Experimental Tests ◽  
Time Axis ◽  
Short Term ◽  
Cost Action ◽  
Term Stability ◽  
Long Term Stability ◽  
Ground Penetrating

<p>Ground Penetrating Radar (GPR) systems need to be calibrated on a recurrent basis and their performance shall be periodically verified, in accordance with manufacturer recommendations and specifications. Nevertheless, most GPR owners in Europe employ their radar units and antennas for years without ever having them verified by manufacturers, unless major flaws or issues become evident. In this framework, Members of COST Action TU1208 have recently carried out a critical analysis of the few existing procedures for the calibration and performance verification of GPR systems; and, they have proposed four improved experimental tests to evaluate the signal-to-noise ratio, short-term stability, linearity in the time axis, and long-term stability of the GPR signal [1]. In this work, we present the results of the tests executed in Novi Sad, Serbia, on a GSSI SIR 3000 control unit equipped with GSSI ground-coupled antennas having central frequencies of 400 MHz and 900 MHz. We have experienced that the execution of the tests helps to attain stronger awareness about the behaviour and limits of owned GPR equipment. It is also interesting to check how the results of the tests change over time and in different environmental conditions, to analyze the performance evolution of the equipment. Main aim of this abstract is to spread the voice and encourage GPR owners and manufacturers to execute the tests. If a wide variety of control units and antennas are tested, of older and more recent conception, with different numbers of working hours, reliable thresholds for the tests can be established and the proposed procedures can be further refined and upgraded. Moreover, the results of the tests can be translated into accuracy levels of measured physical and geometrical quantities, to get some awareness about the uncertainty of results of a GPR survey (e.g., achieved accuracy levels in the estimation of layer thicknesses).</p><p> </p><p>[1] L. Pajewski, M. Vrtunski, Ž. Bugarinović, A. Ristić, M. Govedarica, A. van der Wielen, C. Grégoire, C. Van Geem, X. Dérobert, V. Borecky, S. Serkan Artagan, S. Fontul, V. Marecos, and S. Lambot, "GPR system performance compliance according to COST Action TU1208 guidelines,"  Ground Penetrating Radar, Volume 1, Issue 2, Article ID GPR-1-2-1, July 2018, pp. 2-36, doi.org/10.26376/GPR2018007.</p>

scholarly journals Cross calibration of the Siemens mMR: easily acquired accurate PET phantom measurements, long term stability and reproducibility

2015 ◽  
Vol 2 (S1) ◽  
Author(s):  
Sune H Keller ◽  
Bjorn Jakoby ◽  
Adam Espe Hansen ◽  
Susanne Svalling ◽  
Thomas L Klausen
Keyword(s):  
Term Stability ◽  
Long Term Stability ◽  
Phantom Measurements ◽  
Cross Calibration

scholarly journals Cross-calibration of the Siemens mMR: easily acquired accurate PET phantom measurements, long-term stability and reproducibility

2016 ◽  
Vol 3 (1) ◽  
Author(s):  
Sune H. Keller ◽  
Björn Jakoby ◽  
Susanne Svalling ◽  
Andreas Kjaer ◽  
Liselotte Højgaard ◽  
...  
Keyword(s):  
Term Stability ◽  
Long Term Stability ◽  
Phantom Measurements ◽  
Cross Calibration

scholarly journals Radiometric flight results from the HyperSpectral Imager for Climate Science (HySICS)

2017 ◽  
Vol 6 (1) ◽  
pp. 169-191 ◽  
Author(s):  
Greg Kopp ◽  
Paul Smith ◽  
Chris Belting ◽  
Zach Castleman ◽  
Ginger Drake ◽  
...  
Keyword(s):  
Near Infrared ◽  
Solar Spectrum ◽  
Climate Science ◽  
Trend Detection ◽  
Imaging Spectrometer ◽  
Long Term Stability ◽  
Order Of Magnitude ◽  
Lunar Observations ◽  
Cross Calibration

Abstract. Long-term monitoring of the Earth-reflected solar spectrum is necessary for discerning and attributing changes in climate. High radiometric accuracy enables such monitoring over decadal timescales with non-overlapping instruments, and high precision enables trend detection on shorter timescales. The HyperSpectral Imager for Climate Science (HySICS) is a visible and near-infrared spatial/spectral imaging spectrometer intended to ultimately achieve ∼ 0.2 % radiometric accuracies of Earth scenes from space, providing an order-of-magnitude improvement over existing space-based imagers. On-orbit calibrations from measurements of spectral solar irradiances acquired by direct views of the Sun enable radiometric calibrations with superior long-term stability than is currently possible with any manmade spaceflight light source or detector. Solar and lunar observations enable in-flight focal-plane array (FPA) flat-fielding and other instrument calibrations. The HySICS has demonstrated this solar cross-calibration technique for future spaceflight instrumentation via two high-altitude balloon flights. The second of these two flights acquired high-radiometric-accuracy measurements of the ground, clouds, the Earth's limb, and the Moon. Those results and the details of the uncertainty analyses of those flight data are described.

scholarly journals Radiometric flight results from the HyperSpectral Imager for Climate Science (HySICS)

2016 ◽  
Author(s):  
Greg Kopp ◽  
Paul Smith ◽  
Chris Belting ◽  
Ginger Drake ◽  
Joey Espejo ◽  
...  
Keyword(s):  
Near Infrared ◽  
Solar Spectrum ◽  
Climate Science ◽  
Trend Detection ◽  
Imaging Spectrometer ◽  
Long Term Stability ◽  
Order Of Magnitude ◽  
Lunar Observations ◽  
Cross Calibration

Abstract. Long-term monitoring of the Earth-reflected solar-spectrum is necessary for discerning and attributing changes in climate. High radiometric-accuracy enables such monitoring over decadal timescales with non-overlapping instruments, and high precision enables trend detection on shorter timescales. The Hyperspectral Imager for Climate Science (HySICS) is a visible and near-infrared spatial/spectral imaging-spectrometer intended to ultimately achieve ~ 0.2 % radiometric accuracies of Earth scenes from space, providing an order-of-magnitude improvement over existing space-based imagers. On-orbit calibrations from measurements of spectral solar irradiances acquired by direct views of the Sun enable radiometric calibrations with superior long-term stability than currently possible with any manmade spaceflight light-source or detector. Solar- and lunar-observations enable in-flight focal-plane-array flat-fielding and other instrument calibrations. The HySICS has demonstrated this solar cross-calibration technique for future spaceflight instrumentation via two high-altitude balloon flights. The second of these two flights acquired high radiometric-accuracy measurements of the ground, clouds, the Earth's limb, and the Moon. Those results and the details of the uncertainty analyses of those flight data are described.

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