Radar Distance Measurements in Over-sized Circular Waveguides

2006 ◽  
Author(s):  
T. Musch ◽  
N. Pohl ◽  
M. Gerding ◽  
B. Will ◽  
J. Hausner ◽  
...  
Keyword(s):  
Distance Measurements ◽  
Circular Waveguides

High Precision Radar Distance Measurements in Overmoded Circular Waveguides

2007 ◽  
Vol 55 (6) ◽  
pp. 1374-1381 ◽  
Author(s):  
Nils Pohl ◽  
Michael Gerding ◽  
Bianca Will ◽  
Thomas Musch ◽  
Josef Hausner ◽  
...  
Keyword(s):  
High Precision ◽  
Distance Measurements ◽  
Circular Waveguides

scholarly journals Radar distance measurements in circular waveguides involving intermodal dispersion effects

2010 ◽  
Vol 2 (3-4) ◽  
pp. 409-417 ◽  
Author(s):  
Eckhard Denicke ◽  
Gunnar Armbrecht ◽  
Ilona Rolfes
Keyword(s):  
Measurement Precision ◽  
Level Control ◽  
Distance Measurements ◽  
Dispersion Effects ◽  
Waveguide Transition ◽  
Measurement Results ◽  
Intermodal Dispersion ◽  
Circular Waveguides ◽  
Signal Complexity ◽  
Waveguide Transitions

This contribution deals with guided radar distance measurements in the field of industrial tank level control. The aim is to achieve a submillimeter gauging accuracy even when conducting the measurement within a highly dispersive environment of large and thus overmoded circular waveguides. Normally, multimode propagation causes a decrease in measurement precision. Therefore, the effects of intermodal dispersion are fundamentally reviewed and, based on these results, a correlation-based signal processing method is presented. This method is able to exploit the otherwise parasitic dispersion effects to enhance the measurement precision even in constellation with a simple waveguide transition or antenna, respectively. Furthermore, considerations on the mode variety and its influence on the signal complexity as well as investigations on the technique's reliability and accuracy are presented. Measurement results in a frequency range of 8.5–10.5 GHz are provided for three different kinds of waveguide transitions proving the capability of the method.

scholarly journals Compact mode-matched excitation structures for radar distance measurements in overmoded circular waveguides

2008 ◽  
Vol 6 ◽  
pp. 9-17 ◽  
Author(s):  
G. Armbrecht ◽  
E. Denicke ◽  
I. Rolfes ◽  
N. Pohl ◽  
T. Musch ◽  
...  
Keyword(s):  
Circular Waveguide ◽  
Design Criterion ◽  
Distance Measurements ◽  
Mode Suppression ◽  
Spurious Mode ◽  
Propagation Effects ◽  
Circular Waveguides ◽  
Radar Measurements ◽  
Waveguide Transitions ◽  
Waveguide Taper

Abstract. This contribution deals with guided radar level measurements of liquid materials in large metal tubes, so-called stilling wells, bypass or still pipes. In the RF domain these tubes function as overmoded circular waveguides and mode-matched excitation structures like waveguide tapers are needed to avoid higher order waveguide modes. Especially for high-precision radar measurements the multimode propagation effects need to be minimized to achieve submillimeter accuracy. Therefore, a still pipe simulator is introduced with the purpose to fundamentally analyze the modal effects. Furthermore, a generalized design criterion is derived for the spurious mode suppression of compact circular waveguide transitions under the constraint of specified accuracy levels. According to the obtained results, a promising waveguide taper concept will finally be presented.

scholarly journals Microarcsec Astrometry: The Gaia Mission

1998 ◽  
Vol 11 (1) ◽  
pp. 581-582
Author(s):  
L. Lindegren ◽  
M.A.C. Perryman
Keyword(s):  
Accurate Determination ◽  
Distance Measurements ◽  
Profound Impact ◽  
Individual Stars ◽  
The Galaxy ◽  
Direct Distance ◽  
Scientific Potential ◽  
Space Astrometry ◽  
Small Instrument

The Hipparcos mission demonstrated the efficiency of space astrometry (in terms of number of objects, accuracy, and uniformity of results) and the fact that a relatively small instrument can have a very large scientific potential in the area of astrometry. However, Hipparcos could probe less than 0.1 per cent of the volume of the Galaxy by direct distance measurements. Using a larger instrument and more efficient detectors, it is now technically feasible to increase the efficiency of a space astrometry mission by several orders of magnitude, thus encompassing a large part of the Galaxy within its horizon for accurate determination of parallaxes and transverse velocities. Such a mission will have immediate and profound impact in the areas of the physics and evolution of individual stars and of the Galaxy as a whole.

scholarly journals DL-based segmentation of endoscopic scenes for mitral valve repair

2020 ◽  
Vol 6 (1) ◽  
Author(s):  
Matthias Ivantsits ◽  
Lennart Tautz ◽  
Simon Sündermann ◽  
Isaac Wamala ◽  
Jörg Kempfert ◽  
...  
Keyword(s):  
Mitral Valve ◽  
Minimally Invasive ◽  
Mitral Valve Repair ◽  
Video Stream ◽  
Field Of View ◽  
Valve Repair ◽  
Distance Measurements ◽  
Anatomical Structures ◽  
Endoscopic Video ◽  
Camera Position

AbstractMinimally invasive surgery is increasingly utilized for mitral valve repair and replacement. The intervention is performed with an endoscopic field of view on the arrested heart. Extracting the necessary information from the live endoscopic video stream is challenging due to the moving camera position, the high variability of defects, and occlusion of structures by instruments. During such minimally invasive interventions there is no time to segment regions of interest manually. We propose a real-time-capable deep-learning-based approach to detect and segment the relevant anatomical structures and instruments. For the universal deployment of the proposed solution, we evaluate them on pixel accuracy as well as distance measurements of the detected contours. The U-Net, Google’s DeepLab v3, and the Obelisk-Net models are cross-validated, with DeepLab showing superior results in pixel accuracy and distance measurements.

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