Long distance site diversity characteristics measurement results via JCSAT by using one Earth station measuring method

2002 ◽  
Author(s):  
T. Hatsuda ◽  
N. Okuno ◽  
H. Nagase ◽  
K. Kojyo ◽  
K. Kojima ◽  
...  
Keyword(s):  
Measuring Method ◽  
Long Distance ◽  
Earth Station ◽  
Measurement Results ◽  
Site Diversity

Basic communication sciences

1969 ◽  
Vol 308 (1493) ◽  
pp. 183-198
Keyword(s):  
Long Distance ◽  
Earth Station ◽  
Early Communication ◽  
Technical Developments ◽  
Radiated Power ◽  
The Earth ◽  
Distance Communication ◽  
Quality Of Transmission ◽  
Communication Equipment

The feasibility and utility of long-distance communication via Earth-orbiting satellites has been demonstrated during recent years and it is appropriate therefore to focus attention on the more important scientific studies and technical developments that will be needed if full use is to be made of this valuable mode of communication in the future. The early communication satellites (the Telstar and Relay series) were pioneers in a relatively unknown propagation environment. The satellites themselves were conceptually simple and the communication equipment consisted essentially of a frequency-changing transponder with an r. f. power output of a few watts and a bandwidth some tens of megahertz. Carrier frequencies in the range 2 to 6 GHz were employed; typically either 2 or 6 GHz was used for transmission and 4 GHz for reception at the Earth station. To obtain an adequate signal/noise ratio at the output of the Earth station receiver, frequency modulation was employed, the frequency deviations being greater than those used on terrestrial microwave links. Launcher limitations and other factors meant that the satellites had to be placed in inclined elliptical orbits (see figure 1) with maximum heights of only a few thousand miles. Nevertheless, these satellites demonstrated that some hundreds of frequency-division multiplex telephony circuits, or a television channel, could be achieved with generally satisfactory quality of transmission. It is to be noted, however, that the satellite transponders accommodated only one, or at the most two, r. f. carriers at any time, and that the transmission performance was at times marginal due to limitations of the satellite effective radiated power. Furthermore, these relatively low orbit satellites provided communication in periods of generally less than an hour at a time and required continuous tracking by the Earth station aerials, due to movement of the satellites relative to the Earth.

Development of a Partial Discharge Measuring Method for a Long‐Distance Cable Line

2019 ◽  
Vol 14 (7) ◽  
pp. 996-1001 ◽  
Author(s):  
Nhet Ra ◽  
Nur Sabihah Binti Mustafa ◽  
Tomohiro Kawashima ◽  
Yoshinobu Murakami ◽  
Naohiro Hozumi
Keyword(s):  
Partial Discharge ◽  
Measuring Method ◽  
Cable Line ◽  
Long Distance

Theoretical investigation into the measurability of rail unevenness and corrugation using the dynamic response of axle box and bogie

2020 ◽  
pp. 095440972092321
Author(s):  
Yurong Wang
Keyword(s):  
Dynamic Response ◽  
Standing Waves ◽  
Vehicle Speed ◽  
Long Distance ◽  
Rail Corrugation ◽  
Track Maintenance ◽  
Track System ◽  
Measurement Results ◽  
Ballasted Track ◽  
Rail Irregularity

Monitoring track unevenness is important for noise and vibration control and track maintenance. Rail corrugation and shorter wavelength track unevenness can be measured using the corrugation analysis trolley, but it is not suitable for measurement over long distance. It is of great significance to study the dynamic behavior of the response of the axle box and bogie to the unevenness excitation for a better understanding of the measurement results. In this paper, the dynamic response of the axle box and bogie to the unevenness excitation is analyzed in the frequency domain by taking account of multiple wheel–rail interactions, which is the case in practice. The response of the axle box and bogie is found to be affected by the so-called P2 resonances at low and medium frequencies and the standing waves of rail vibration at higher frequencies due to the multiple wheel–rail interactions. Based on the analysis of the response of the axle box and bogie, the measurability of track unevenness is discussed. Results show that the measurement of rail unevenness using the axle box response is mainly limited by the P2 resonance. The frequency range of measurement for the ballasted track studied is estimated to be 1–35 Hz, corresponding to the measurable unevenness wavelength of 0.6–20 m (or longer) at a vehicle speed of 20 m/s. Above 200 Hz, the standing waves of rail vibration will cause serious uncertainty in the measurement of short wavelength rail irregularity using the axle box response for the resilient track. Short pitch rail corrugation, however, can be evaluated using the axle box response due to its strong correlation with certain modes of the wheel–track system.

scholarly journals Ku-Band Long Distance Site-Diversity (SD) Characteristics Using New Measuring System

2004 ◽  
Vol 52 (6) ◽  
pp. 1481-1491 ◽  
Author(s):  
T. Hatsuda ◽  
Y. Aoki ◽  
H. Echigo ◽  
F. Takahata ◽  
Y. Maekawa ◽  
...  
Keyword(s):  
Measuring System ◽  
Long Distance ◽  
Site Diversity ◽  
Ku Band

scholarly journals Evaluation of the Diethylene Glycol Regeneration rate in Gas Fields Based on Indirect Measurements

2021 ◽  
Vol 2096 (1) ◽  
pp. 012120
Author(s):  
A N Krasnov
Keyword(s):  
Diethylene Glycol ◽  
Treatment Plant ◽  
Treatment Efficiency ◽  
Long Distance ◽  
Indirect Measurements ◽  
Regeneration Rate ◽  
Gas Treatment ◽  
Measurement Results ◽  
Gas Fields

Abstract Gas dehydration in the field is a mandatory procedure before long-distance transportation. In Russia, gas is dried by absorption using diethylene glycol (DEG). Upon absorbing moisture from the raw gas, DEG is regenerated and recycled to dehydration, the quality of which largely depends on the regeneration rate. This indicator is not measured directly at the dehydration plant, and regeneration is controlled discretely based on the periodic laboratory analysis results. The paper describes a virtual analyzer determining the DEG concentration in a real-time mode based on the temperature and DEG consumption measurement results. The regression mathematical model underlying the virtual analyzer has been built based on experimental data obtained at the Yamburg gas condensate field. As part of the gas treatment plant APCS, a virtual analyzer improves the treatment efficiency and reduces the DEG consumption.

Heralded Entanglement Between Widely Separated Atoms

Science ◽  
2012 ◽  
Vol 337 (6090) ◽  
pp. 72-75 ◽  
Author(s):  
Julian Hofmann ◽  
Michael Krug ◽  
Norbert Ortegel ◽  
Lea Gérard ◽  
Markus Weber ◽  
...  
Keyword(s):  
Quantum Mechanics ◽  
Quantum Communication ◽  
Information Science ◽  
Essential Feature ◽  
Quantum Systems ◽  
Long Distance ◽  
Quantum Information Science ◽  
Classical Statistics ◽  
Measurement Results ◽  
Generation Of Entanglement

Entanglement is the essential feature of quantum mechanics. Notably, observers of two or more entangled particles will find correlations in their measurement results that cannot be explained by classical statistics. To make it a useful resource, particularly for scalable long-distance quantum communication, the heralded generation of entanglement between distant massive quantum systems is necessary. We report on the creation and analysis of heralded entanglement between spins of two single rubidium-87 atoms trapped independently 20 meters apart. Our results illustrate the viability of an integral resource for quantum information science, as well as for fundamental tests of quantum mechanics.

Research on the Vector Measure Method of Coordinate Measuring Machine

2013 ◽  
Vol 561 ◽  
pp. 572-575
Author(s):  
Zhao Lin Han ◽  
Mao Xing Yuan
Keyword(s):  
Vector Measure ◽  
Coordinate Measuring Machine ◽  
Measuring Method ◽  
The Poor ◽  
Measurement Results ◽  
Measuring Machine

When we use Coordinate Measuring Machine to measure some points of the workpieces, the wrong measuring method will get the poor repeatability and poor reproducibility of measurement results. Now the vector measure of the CMM is a more convenient way. The main principles are analyzed in this paper, and a workpiece is measured for example.

scholarly journals Method of improving large-scale measurement accuracy of laser tracker based on photogrammetry

2019 ◽  
Vol 52 (9-10) ◽  
pp. 1220-1227 ◽  
Author(s):  
Chengyang Zhang ◽  
Xishuang Jing ◽  
Siyu Chen ◽  
Xuanzhe Ling ◽  
Jiarong Zou ◽  
...  
Keyword(s):  
Large Scale ◽  
Measurement Accuracy ◽  
Measurement Data ◽  
Correction Method ◽  
Laser Tracker ◽  
Digital Measurement ◽  
Long Distance ◽  
Measurement Results ◽  
High Measurement ◽  
Coordinate Correction

Background: When performing the spatial large-scale measurements, the measurement accuracy of laser tracker would decreased with the increase of the measurement distances due to the refraction difference of most optical digital measurement devices. Therefore, this paper proposed a method based on photogrammetry system to improve the large-scale measurement accuracy of the laser tracker. Purpose: The purpose of this method is to improve the large-scale measurement accuracy of the laser tracker by considering the advantages of photogrammetry system such as high measurement accuracy and good portability. Methods: The measurement data from the photogrammetry system would be used as a reference to do correction on measurement results from laser tracker. The coordinate correction method based on Rodrigues’ rotation formula has been discussed. The measurement accuracy of the long-distance point of laser tracker can be significantly improved through the coordinate correction method. Conclusion: Based on the advantages of using photogrammetry system, the proposed method can achieve higher accuracy when measuring the common points at a closer distance than the laser tracker can do when measuring objects far away from instrument. The feasibility of the proposed method has been demonstrated by experiment.

Design of Long-Distance and High-Accuracy Rail Subgrade Deformation Monitoring System Based on Zigbee Wireless Network

2013 ◽  
Vol 303-306 ◽  
pp. 676-684 ◽  
Author(s):  
Chun Hui Gong ◽  
Guo Qiang Zeng ◽  
Liang Quan Ge ◽  
Cheng Jun Tan ◽  
Qun Luo ◽  
...  
Keyword(s):  
Wireless Network ◽  
Monitoring System ◽  
Satellite System ◽  
High Accuracy ◽  
Deformation Monitoring ◽  
Long Distance ◽  
Term Stability ◽  
Long Term Stability ◽  
Remote Server ◽  
Measurement Results

A design of long-distance and high-accuracy rail subgrade deformation monitoring system based on Zigbee wireless network is proposed according to the requirement of inclination measurement for the Qinghai-Tibet railway rail subgrade. This paper selects Atmega128 as the microprocessor of the system, and uses SCA103T as high accuracy inclination sensor. When the real time inclination data has been collected and analyzed, GPRS network and Beidou satellite system should send the data to remote server, which can exhibit the deformation of rail subgrade after processing and analyzing the data comprehensively. The measurement results show that the short-term stability reaches 0.01°, and long-term stability reaches 0.02°. The final application distance is nearly 378 kilometers.

Vision Based Measurement of Refueling Drogue for Autonomous Aerial Refueling

2014 ◽  
Vol 590 ◽  
pp. 618-622
Author(s):  
Xu Feng Wang ◽  
Xin Min Dong ◽  
Xing Wei Kong ◽  
Jian Hui Zhi
Keyword(s):  
Experimental System ◽  
Measuring Method ◽  
Monocular Vision ◽  
Recognition Method ◽  
Long Distance ◽  
Aerial Refueling ◽  
Experimental Scheme ◽  
Aerial Vehicle ◽  
Measuring Experiment ◽  
Detection And Recognition

Autonomous aerial refueling (AAR) can improve the long-distance and rapid strike capacities of an unmanned aerial vehicle (UAV) significantly by extending its range as well as loiter time. This paper has mainly studied on the measurement of refueling drogue during the docking phase of the probe-drogue UAV-AAR. Firstly, the monocular vision based drogue detection and recognition method is presented. Secondly, the measuring method of relative position between the drogue and UAV based on the model of camera calibration is researched. Finally, the semi-physical experimental system of drogue spacial location for UAV-AAR during short-range docking phase is constructed. The drogue measuring experiment based on monocular vision is implemented, and the performance of the monocular vision method for drogue measurement and the validity of the experimental scheme are verified.

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