Radar Distance Measurements in Over-sized Circular Waveguides

Author(s):  
T. Musch ◽  
N. Pohl ◽  
M. Gerding ◽  
B. Will ◽  
J. Hausner ◽  
...  
2007 ◽  
Vol 55 (6) ◽  
pp. 1374-1381 ◽  
Author(s):  
Nils Pohl ◽  
Michael Gerding ◽  
Bianca Will ◽  
Thomas Musch ◽  
Josef Hausner ◽  
...  

2010 ◽  
Vol 2 (3-4) ◽  
pp. 409-417 ◽  
Author(s):  
Eckhard Denicke ◽  
Gunnar Armbrecht ◽  
Ilona Rolfes

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.


2008 ◽  
Vol 6 ◽  
pp. 9-17 ◽  
Author(s):  
G. Armbrecht ◽  
E. Denicke ◽  
I. Rolfes ◽  
N. Pohl ◽  
T. Musch ◽  
...  

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.


1998 ◽  
Vol 11 (1) ◽  
pp. 581-582
Author(s):  
L. Lindegren ◽  
M.A.C. Perryman

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.


2020 ◽  
Vol 6 (1) ◽  
Author(s):  
Matthias Ivantsits ◽  
Lennart Tautz ◽  
Simon Sündermann ◽  
Isaac Wamala ◽  
Jörg Kempfert ◽  
...  

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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