Calibration of Frequency Shift System of Wind Imaging Interferometer

2020 ◽  
Vol 86 (12) ◽  
pp. 753-760
Author(s):  
Yongqiang Sun ◽  
Chunmin Zhang ◽  
Pengju Zhang ◽  
Tingkui Mu ◽  
Tingyu Yan ◽  
...  
Keyword(s):  
Wind Speed ◽  
Frequency Shift ◽  
Single Factor ◽  
System Calibration ◽  
Calibration Process ◽  
Accuracy Requirement ◽  
Imaging Interferometer ◽  
System Vibration

In this paper, the frequency shift system calibration of the wind imaging interferometer is analyzed. By establishing the frequency shift system vibration and reflectivity models, the single factor and comprehensive factors models are used to invert the wind speed and temperature, respectively. The parameters of the frequency shift system that meet the design accuracy requirement of the instrument are determined. The conclusion of this paper provides theoretical instructions for the calibration process of wind imaging interferometer.

Assessment of the sea surface wind and current retrieval from ALOS-2 and Sentinel-1 SAR data over coastal areas

2021 ◽  
Author(s):  
Anis Elyouncha ◽  
Leif E. B. Eriksson
Keyword(s):  
Wind Speed ◽  
Frequency Shift ◽  
Doppler Shift ◽  
Surface Wind ◽  
Surface Current ◽  
Doppler Frequency ◽  
Doppler Frequency Shift ◽  
Sea Surface ◽  
Surface Velocity ◽  
L Band

<p><span>Synthetic aperture radar (SAR) has become an essential component in ocean remote sensing due it’s </span><span>high</span> <span>sensitivity</span><span> to sea surface dynamics and its high spatial resolution. </span><span>The ALOS-</span><span>2 SAR</span><span> data are </span> underutilized <span>for</span><span> ocean surface wind and current retrieval. Althou</span><span>g</span><span>h the primary goals of the </span><span>ALOS-2</span><span> mission are focused on land applications, the extension of the satellite scenes over the coast</span><span>al areas</span><span> offers an opportunity for ocean applications. Th</span><span>e</span><span> underutilization </span><span>of ALOS-2 data </span><span>is mainly due to the fact that at low radar frequencies, e.g. L-band, the sensitivity of the radar scattering coefficient to wind speed and the sensitivity of the Doppler frequency shift to sea surface velocity is lower than at higher frequencies, e.g. C- </span><span>and</span><span> X-</span><span>band</span><span>. </span><span>This is also due to the fact that most of ALOS-2 images are acquired in HH or HV polarization while the VV polarization is often preferred in ocean applications due the higher signal to noise ratio. </span></p><p>The wind speed is retrieved from Sentinel-1 and ALOS-2 using the existing empirical C- and L-band geophysical model functions. For Sentinel-1, the Doppler frequency shift provided in the OCN product is used. For ALOS-2, the Doppler frequency shift is estimated from the single look complex data using the pulse-pair processing method. The estimated Doppler shift converted to the surface radial velocity and the velocity is calibrated using land as a reference. The estimated L-band Doppler shift and surface velocity is compared to the C-band Doppler shift provided in the Sentinel-1 OCN product. Due the difference in the local time of ascending node (about 6 hours at the equator) of the two satellites, a direct pixel-by-pixel comparison is not possible, i.e. the wind and surface current can not be assumed to be constant during such a large time difference. Thus, the retrieved wind from each sensor is compared separately to model data and in-situ observations.</p><p>In this paper, the quality of the wind speed retrieved from the L-band SAR (ALOS-2) in coastal areas is assessed and compared to the C-band SAR (Sentinel-1). In addition, the feasibility of the surface current retrieval from the L-band Doppler frequency shift is investigated and also compared to Sentinel-1. Examples will be shown and discussed. This opens an opportunity for synergy between L-band and C-band SAR missions to increase the spatial and temporal coverage, which is one of the main limitations of SAR application in ocean remote sensing.</p>

scholarly journals EFFECT OF FAN’S PARAMETERS ON ADHESION MECHANISM OF THRESHED RAPE MIXTURE TO CLEANING SIEVE

2020 ◽  
pp. 211-218
Author(s):  
Zhang Tao ◽  
Li Yaoming ◽  
Xu Lizhang ◽  
Qing Yiren
Keyword(s):  
Wind Speed ◽  
Theoretical Analysis ◽  
Single Factor ◽  
Key Factors ◽  
Technological Parameters ◽  
Adhesion Mechanism ◽  
Box Behnken Design ◽  
Factors Influencing ◽  
Cleaning System ◽  
Combine Harvesters

In order to reduce the adhesion of moist threshed rape mixture and cleaning sieve, a method named “Hot-airflow Cleaning” has been proposed. Firstly, the key factors influencing anti-adhesion property were obtained based on the theoretical analysis. They were temperature, wind speed and fan inclination. Then, based on the single-factor experiments, the proper temperature of the fan was 30-50oC, the proper wind speed and inclination of the fan were 2-4 m/s and 15-45°, respectively. Finally, the fan’s parameters were optimized by Box-Behnken design. The results showed that the optimum technological parameters were temperature of 50 oC, a wind speed of 4 m/s and that fan inclination was 45°. This research could provide a reference for the improvement of cleaning system for rape combine harvesters.

scholarly journals Intercalibration of HRDI and WINDII wind measurements

1997 ◽  
Vol 15 (9) ◽  
pp. 1089-1098 ◽  
Author(s):  
M. D. Burrage ◽  
W. R. Skinner ◽  
P. B. Hays
Keyword(s):  
Wind Speed ◽  
Upper Atmosphere ◽  
The Other ◽  
Data Sets ◽  
Atmospheric Emission ◽  
Validation Test ◽  
Doppler Imager ◽  
Imaging Interferometer ◽  
Wind Measurements

Abstract. The High Resolution Doppler Imager (HRDI) and the Wind Imaging Interferometer (WINDII) in- struments, which are both on the Upper Atmosphere Research Satellite, measure winds by sensing the Doppler shift in atmospheric emission features. Because the two observation sets are frequently nearly coincident in space and time, each provides a very e.ective validation test of the other. Discrepancies due to geophysical di.erences should be much smaller than for comparisons with other techniques (radars, rockets, etc.), and the very large sizes of the coincident data sets provide excellent statistics for the study. Issues that have been examined include relative systematic o.sets and the wind magnitudes obtained with the two systems. A significant zero wind position di.erence of ~6 m s–1 is identified for the zonal component, and it appears that this arises from an absolute perturbation in WINDII winds of –4 m s–1 and in HRDI of +2 m s–1. Altitude o.sets appear to be relatively small, and do not exceed 1 km. In addition, no evidence is found for the existence of a systematic wind speed bias between HRDI and WINDII. However, considerable day-to-day variability is found in the quality of the agreement, and RMS di.erences are surprisingly large, typically in the range of 20±30 m s–1.

The Simulator for the Gas Fuel System – Calibration Process

2016 ◽  
Vol 838 ◽  
pp. 63-70
Author(s):  
Yury Vladimirovich Panov ◽  
Aleksey Nikolaevich Pronnikov ◽  
Krzysztof Lapinski
Keyword(s):  
Control System ◽  
Alternative Fuels ◽  
Gas Injection ◽  
Technical Training ◽  
Fuel System ◽  
Training Process ◽  
System Calibration ◽  
Calibration Process ◽  
Injection Control ◽  
Gas Fuel

The article reviews issues of training process effectiveness increase by means of implementation and adaptation of the simulator of gas injection control system for petrol engine performed by applying LPG TECH Co technologies, when technical training relates to the use of alternative fuels on the motor transport.

wind velocity measurements using sonic techniques1

1964 ◽  
Vol 45 (9) ◽  
pp. 571-580 ◽  
Author(s):  
Gilbert Kelton ◽  
Pierre Bricout
Keyword(s):  
Wind Speed ◽  
Frequency Shift ◽  
Wind Velocity ◽  
Average Difference ◽  
Narrow Beam ◽  
Velocity Measurements ◽  
Sonic Waves ◽  
High Degree

A unique technique has been devised to measure wind speed and direction in space without any local sensor, artificial target, or any structure erected over the ground being necessary. Continuous recordings of wind speed and direction at a distance of 70 ft from a sonic source have been obtained by measuring the frequency shift of sonic waves scattered from a narrow beam generated by a powerful Levavasseur whistle at 10 kc. Two receivers in orthogonal directions with respect to the source provide continuous readings of the horizontal components of wind velocity. The series of over 300 sonic measurements on winds from 3 to 25 mph show average difference readings compared with an Aerovane anemometer not larger than ± 1.0 mph for speed nor ± 5.0° for direction, indicating a high degree of correlation between the sonic system and the more commonly used propeller type anemometers.

scholarly journals Horizontal comparator for the system calibration of digital levels – realization at the Faculty of civil engineering, CTU Prague and in the laboratory of the Department of survey and mapping Malaysia (JUPEM) in Kuala Lumpur.

2015 ◽  
Vol 14 (2) ◽  
pp. 55-61 ◽  
Author(s):  
Zdeněk Vyskočil ◽  
Zdeněk Lukeš
Keyword(s):  
Civil Engineering ◽  
Kuala Lumpur ◽  
Control Software ◽  
System Calibration ◽  
Calibration Process ◽  
Digital Levels

<p>Metrological procedures require a leveling staff calibration for an estimation of a true staff scale.  The calibration process is usually realized on laboratory comparators. Two automatic comparators for digital level calibration were built by the staff of Department of Geomatics. This article brings some information about properties of developed systems and about a control software for the comparators.</p>

Coded-Structured Light System Calibration Using Orthogonal Phase Shift Coding Combined with Zhang’s Method

2014 ◽  
Vol 981 ◽  
pp. 348-351
Author(s):  
Xiao Yang Yu ◽  
Xiao Liang Meng ◽  
Hai Bin Wu ◽  
Xiao Ming Sun ◽  
Li Wang
Keyword(s):  
Phase Shift ◽  
Model Calibration ◽  
Structured Light ◽  
Calibration Method ◽  
Dimensional System ◽  
Plane Model ◽  
System Calibration ◽  
Calibration Process ◽  
Projector Calibration ◽  
Orthogonal Phase

In coded-structured light three dimensional system, system calibration plays a vital role for the measurement accuracy. The camera calibration method is very mature, but the study about projector calibration is less. Therefore, this paper proposes a projector calibration method with simple calibration process and high accuracy. This method combines the Zhang’?s plane model calibration method with orthogonal phase shift coding. In calibration process, this paper uses phase shift coding pattern to establish the relationship of projector image and camera corner point coordinates. According to the image coordinates in the projector’?s perspective, we program and calculate the projector’?s internal and external parameters matrix based on the Zhang’?s plane model calibration toolbox. The results show that the proposed method is simple and flexible, the maximum relative error of the calibration parameters is 0.03%, and it meets the requirements of system calibration in medical or industrial fields.

Improving the atmospheric wind speed measured accuracy by the ground-based airglow imaging interferometer

2017 ◽  
Author(s):  
Yuanhe Tang ◽  
Rui Yang ◽  
Haiyang Gao ◽  
Fengtao Zhai ◽  
Yang Yu ◽  
...  
Keyword(s):  
Wind Speed ◽  
Imaging Interferometer

scholarly journals Calibration of scatterometer wind speed under hurricane conditions

2021 ◽  
Author(s):  
Agustinus Ribal ◽  
Ali Tamizi ◽  
Ian R. Young
Keyword(s):  
Wind Speed ◽  
Microwave Radiometer ◽  
Process Data ◽  
Calibration Process ◽  
Wind Speeds ◽  
Speed Range ◽  
Stepped Frequency ◽  
Spatio Temporal ◽  
Buoy Data ◽  
Calibration Relations

AbstractFour scatterometers, namely: METOP-A, METOP-B, ERS-2 and OCEANSAT-2 were re-calibrated against combined National Data Buoy Center (NDBC) data and aircraft Stepped Frequency Microwave Radiometer (SFMR) data from hurricanes. As a result, continuous calibration relations over the wind speed range 0 to 45 ms-1 were developed. The calibration process uses match-up criteria of 50 km and 30 min for the buoy data. However, due to the strong spatio-temporal wind speed gradients in hurricanes, a method which considers both scatterometer and SFMR data in a storm-centred translating frame of reference is adopted. The results show that although the scatterometer radar cross-section is degraded at high wind speeds, it is still possible to recover wind speed data using the re-calibration process. Data validation between the scatterometers shows that the calibration relations produce consistent results across all scatterometers and reduce the bias and root mean square error compared to previous calibrations. In addition, the results extend the useful range of scatterometer measurements to as high as 45 ms-1.

On a new method in spectroscopy : laser-induced frequency shift of self-excited ion oscillations

1992 ◽  
Vol 2 (7) ◽  
pp. 1367-1372
Author(s):  
R. C. Bobulescu ◽  
M. A. Brǎtescu ◽  
C. Stǎnciulescu ◽  
G. Musa
Keyword(s):  
Frequency Shift ◽  
New Method ◽  
Spectroscopy Laser
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