MEDAV GmbH

Uttenreuth, Germany

MEDAV GmbH

Uttenreuth, Germany

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Malz E.,TU Ilmenau | Thoma R.S.,TU Ilmenau | Zetik R.,TU Ilmenau | Semashko P.,TU Ilmenau | Ariza A.P.G.,MEDAV GmbH
Proceedings - IEEE International Conference on Ultra-Wideband | Year: 2012

In this article we give an overview about the principles of polarimetric Ultrawideband Radar. Starting from the state of the art and a summary of the theory we analyze the calibration principles of polarized UWB Radar Data, we investigate possible imaging algorithms and we list important applications. Finally we show an example, to detect certain targets using a polarimetric MIMO UWB radar by doing an analysis of the radar cross section (RCS) of the individual targets. © 2012 IEEE.


Gulzow T.,University of Kiel | Heute U.,University of Kiel | Kolb H.J.,MEDAV GmbH
European Signal Processing Conference | Year: 2015

In certain radio-surveillance applications, speech signals with uncertain carrier frequencies may be detected. Beyond other disturbances, carrier mismatches distort the demodulated SSB signals by frequency shifts Δ. © 2002 EUSIPCO.


Ariza A.P.G.,MEDAV GmbH | Muller R.,MEDAV GmbH | Wollenschlager F.,MEDAV GmbH | Schulz A.,MEDAV GmbH | And 8 more authors.
IEEE Transactions on Antennas and Propagation | Year: 2013

Polarimetric radio wave processing becomes of increasing interest for very high-data rate wireless transmission and for short-range radar at millimeter-waves (mm-W). This goes along with the huge bandwidth of 7 to 9 GHz, which is available worldwide in the 60 GHz unlicensed band. In this paper, we propose a 60 GHz ultra-wideband (UWB) polarimetric multiple-input-multiple- output (MIMO) sensing system architecture and polarimetric signal processing for short-range communications and radar. Demonstration measurements were made by using an UWB radar interface. By measurements in multipath rich environments it is demonstrated that tap-wise polarimetric filtering in delay domain can enhance the 60 GHz link budget by filtering some paths and then reducing shadowing due to human activity. Additionally, optimum MIMO polarimetric filtering is proposed to reduce heavy clutter for mm-W radar, increasing by about 30 dB the signal-to-clutter-plus-noise-ratio. © 1963-2012 IEEE.


Weidner M.,Medav GmbH | Ernst E.,GKN plc
International Powder Metallurgy Congress and Exhibition, Euro PM 2013 | Year: 2013

Acoustic Resonance Testing (ART) provides an economic solution for line-integrated quality testing to manufacturers of powder-metallurgical parts (see Ref. [1] - [5]). The technique convinces through a high degree of reliability, short measurement cycles for complete component testing and relatively small cost investment. The method uses the fact, that on modern lines mainly faultless parts are produced. It sorts out conspicuous parts, which show acoustic characteristics different from the bulk. After changes of material or production parameters, a new adaption of the abnormality limits is performed. This adaptation has to be stable against changing production scatter. That means that the system's sensitivity against faulty parts within a very homogenous production lot should be comparable to the selectivity necessary to sort out all conspicuous parts within an untypically inhomogeneous production lot. The subsequent contribution discusses how such comparable test conditions can be achieved even if the absolute extent of production scatter differs from lot to lot.


Weidner M.,Medav GmbH | Ernst E.,GKN plc
Euro PM 2014 Congress and Exhibition, Proceedings | Year: 2014

Acoustic Resonance Testing (ART) provides an economic solution for line-integrated quality testing of all kinds of powder-metallurgical or MIM parts. The assessed characteristics directly depend on geometry, density, mass, elastic modulus and stiffness and therefore relate to the steadiness of the component. ART is a comparative method. It sorts out conspicuous parts, which show acoustic characteristics different from the bulk. The technique convinces through a high degree of reliability, short measurement cycles for complete component testing and relatively small cost investment. The subsequent contribution discusses the characteristics of two different ways to achieve sound excitation, namely by an impact device, which is a small electro-mechanical hammer, or by a slide device, where parts fall down on an impingement plate. Based on theoretical and practical considerations, criteria for the choice of the best method for signal generation are presented. Different installations for testing PM and MIM parts at GKN Sinter Metals are presented as example.


Strama O.,MEDAV GmbH | Ernst E.,GKN plc
Proceedings of the International Euro Powder Metallurgy Congress and Exhibition, Euro PM 2012 | Year: 2012

As practice shows, with the help of the Acoustic Resonance Testing (ART) cracks and other quality related issues can be found in test specimens. To make this technique interesting for powder metal production environments from the technical and the economical point of view, a number of requirements have to be taken into account. Today, high quality requirements are in contradiction to the challenge, to provide even security-related components at a low price per part. This, on the other hand, requires quality testing methods, which are able to detect quality related issues with high speed and low operating costs. This contribution shows how these conflicting requirements can be solved by Acoustic Resonance Testing. Starting from the basics of this technique, particular these points are referenced, which are crucial for stable long-time operation at the PM production. One of the main requirements is the assessment of the typical production scatter. Usually, the issues to be detected have smaller influences on the resonance frequencies than the production deviations over a long time. The presented MEDAV technique allows detection of conspicuous parts in a series of produced parts, even if they are covered by the overall production scatter. This is solved by an automatic and adaptive algorithm, which can be optimized by a so called quality evaluation loop to avoid pseudo rejects by simultaneously detection of relevant issues.


Strama O.,MEDAV GmbH | Ernst E.,GKN plc
Proceedings of the Euro International Powder Metallurgy Congress and Exhibition, Euro PM 2011 | Year: 2011

Acoustic Resonance Testing (ART) provides an economic solution for line-integrated quality testing to manufacturers of powder-metallurgical parts. The technique convinces through a high degree of reliability, short measurement cycles for complete component testing and relatively small cost investment. Present organisational and technical demands to the operators can be fulfilled by engaged and available machine operators. Characteristic for the technique is a relatively elaborate preliminary examination of the natural vibrations, the implementation of a part specific test rig and series-accompanying measurements for system adjustment. The subsequent contribution summarises the basics of this technique. The characteristic of the MEDAV technology is that the adjustment of the test set-up is done automatically under application of statistical methods to unsorted series parts and the adaption of the abnormality limits. At the end, best practices for the introduction of ART in the production line are described.


A method and a system for TDOA-locating of an unknown emitter of RF-Signals are provided, wherein the sensor devices operate in an only roughly synchronized mode without a precis synchronisation by an exact timing reference. The only roughly synchronized mode of operation causes location offsets in the measurement results. For compensation of these offsets a reference emitter with a precisely known location is chosen. The location of the reference emitter is measured in the only roughly synchronized mode of operation. The measurement results are are compared with the known position of the reference emitter, and the location offsets are obtained. These now known location offsets are used to correct the measurement results of unknown emitters in the same measurement session.


A method and an apparatus for TDOA-locating of an unknown emitter of RF-signals are provided, wherein the amount of data that have to be transmitted from the sensor devices to the processing centre of the locating system is greatly reduced. According to the invention the signals received at the sensor devices of the locating system are synchronized, sampled and autocorrelated. The autocorrelation function thus obtained is divided into segments of an appropriate duration. The maximums of the autocorrelation function in each segment provide a unique characterizing feature of the time of arrival of the RF-signals at each sensor device. The maximums of the autocorrelation function are transmitted to the processing centre of the system. The travelling time difference of the sensor signals needed for locating the unknown emitter are simply computed by the differences of the transmitted maximums.


The invention provides a method and an apparatus for measuring the travelling time difference of a bandlimited signal that is transmitted from one emitter over at least two channels having different delays to at least two receivers. The emitter and the receivers may be stationary or moving. Basically the channels are undisturbed channels, but in general the channels may be disturbed by reflections of stationary or moving reflectors and multipath effects. The received signals are sampled and interpolated in a suitable way. The cross-correlation function of each two sampled and interpolated signals is calculated. The disturbing effects of movement, reflections and multipath effects are removed from the cross-correlation function, and a cleaned up cross-correlation function is provided that only represents the undisturbed channel. A continuous smooth curve is fitted to the maximum values of the cleaned up cross-correlation function. The maximum of the smooth curve provides an improved value for the travelling time difference.

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