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László Sujbert, György Orosz
FFT-based Identification of Data Loss Models

Recently measurement data loss has been of greater interest, due to the spread of sensor networks and the idea of Internet of things. A procedure is proposed that is able to identify the most frequently employed data loss models. It is assumed that the communication protocol provides information about data loss, i.e. the so-called data availability indicator function is known. The power spectral density (PSD) of the indicator function is representative for the model, and can be used for identification. Spectral estimation is carried out by Fast Fourier Transform (FFT) based techniques. The paper introduces the identification procedure for random independent, random block-based and a Markov model-based data loss patterns. The efficiency of the proposed method is demonstrated by simulation and measurement results.

Bence Tilk
Automated lung segmentation on digital tomosynthesis images with complex method

For lung screening the most common method is chest radiography, which produces summation images without giving any depth information about the lung. Computed Tomography (CT) creates excellent slice images, which give volume data that makes CT a more sensitive nodule detection system. However CT has disadvantages, it is too expensive and it’s x-ray emission is too high to be used as an everyday screening method. Digital tomosynthesis (DTS), as a relatively new chest imaging modality, can be positioned between chest radiography and CT. While it produces slice images of the chest similarly to CT, its slice thickness is larger, it creates a bit more blurred slices, it has much lower radiation than CT. This blurring makes it hard to segment the lung areas automatically, which is essential for an efficient Computeraided Diagnosis system. The paper proposes a combined method, which starts from a previously published approach, extends it using snake methods and adjacent images’ segmentation information to improve lung segmentation. Experiments show that the combination of methods reduces the incorrectly segmented lung region.

Christian Mentin, Robin Priewald, Eugen Brenner
Knife Edge Diffraction for Spatially Extended Light Sources

The position of an object’s edge can be determined from its shadow projected onto a CCD or CMOS sensor without any additional optical elements such as lenses. Nevertheless, in many applications a collimated Laser light beam is used to illuminate the measured object. Since laser diodes are often complicated in handling, and mostly need additional expensive Laser driver hardware, new approaches were considered. Spatially extended light sources such as off-the-shelf LEDs could be used for edge detection in combination with diffraction pattern analysis, without the need of any additional collimation optics for illumination. Results and applicability for simple position measurement are discussed.

Ali Haroun, Manel Ben-Romdhane, Rihab Lahouli, Chiheb Rebai, Dominique Dallet
Digital Reconstruction Stage Implementation of FBD Sigma Delta ADC for SDR Receiver

This paper presents a fixed point implementation of a digital reconstruction stage in frequency band decomposition (FBD) Sigma Delta analog-to-digital converter (ADC) which is intended for software defined radio (SDR) multistandard receiver. The implemented architecture is composed of 3 parallel branches for the UMTS use case. The digital reconstruction stage is essentially composed of digital finite impulse response (FIR) filters. In addition, the frequency conversions performed in the digital reconstruction stage are ensured by digital oscillators which are carefully tuned to obtain the required frequencies and phases. These oscillators are dedicated to demodulation and modulation operations. The proposed architecture is digitally implemented on a field programmable gate array (FPGA) target. Then, it is tested thanks to FPGA-inthe-loop (FIL) tool using MATLAB/SIMULINK interface. It allows us to compare our system to the simulation results that are done with MATLAB/SIMULINK in floating point.

Daniel Belega, Dario Petri, Dominique Dallet
Accurate sine-wave frequency estimation by means of an interpolated DTFT algorithm

An Interpolated Discrete Time Fourier Transform (IpDTFT) algorithm for sine-wave frequency estimation is proposed in this paper. It generalizes the classical interpolated Discrete Fourier Transform (IpDFT) algorithm by interpolating two DTFT spectrum samples located one frequency bin apart. The influence on the estimated frequency of the spectral image component is investigated in the case when the acquired sine-wave samples are weighted by a Maximum Sidelobe Decay (MSD) window. An analytical expression for the estimation error due to the spectral image component is derived. Leveraging on that expression an iterative procedure for the reduction of the effect of spectral image component on the estimated frequency is proposed. The accuracies of the proposed procedure and other state-of-the-art interpolated DFT algorithms are compared by means of both computer simulations and experimental results. It is shown that the proposed procedure can be advantageously adopted when the number of acquired sine-wave cycles is small.

Zivko Kokolanski, Cvetan Gavrovski, Vladimir Dimcev, Dimitar Taskovski
Low-cost Multi-Channel Interface for Passive Resistive Sensors

The paper elaborates the design and implementation of a low-cost multichannel interface for passive resistive sensors. The interface is based on a multivibrator in a monostabile configuration and is suitable for direct interface to a programmable devices (e.g. microcontrollers, field programmable gate arrays, etc.). In the paper, details concerning the sensor interface are presented, and different calibration techniques are described. The theoretical analysis are supported by a practical implementation.

Daniel Petrisor, Cristian Zet, Cristian Fosalau
Data Consistency and Fault Management in Local Sensor Networks used for Landslide Surveillance

In this paper we are presenting a data consistency and fault management architecture, developed for a local embedded sensor network used for landslide surveillance. Landslide sensor responses measured from multiple points are used by our software architecture to compute a local landslide displacement and orientation. Landslide sensors are checked by our architecture for data consistency and fault management. Our approach implements a fault tolerant architecture, where a measurement point that is identified, tested and verified to be faulty is removed from the list of addressed sensors in order to ensure data integrity. Fault tolerant architecture is integrated at node level, where possible diagnostic fault codes received from measurement points are managed. Decisions to exclude measurement points from the network are made based on the occurrence and persistence of specific diagnostic fault codes.

Dávid Vincze, Tamás Kovácsházy
Benchmark Tool for the Characterization of the Real-Time Performance of Linux on System on a Chip Platforms for Measurement Systems

The complexity of measurement systems grows rapidly. Such complex systems cannot be constructed without the high-level software abstraction provided by embedded operating systems that make hardware handling and communication services much easier to implement. Today, Linux is the dominant high-end operating system in the embedded world; however, its scheduling performance is not much investigated using measurements in sufficient detail. The paper introduces such study in which Linux's scheduling performance is investigated for various programming models (ranging from a simple application written in JavaScript or in Bash shell script to the real-time scheduling classes in Linux) and for two System on a Chip (SoC) platforms for specified kernel versions. The results of this study present valuable information for application developers in their current form. However, doing the measurements is time consuming and error prone in its current form because it must be conducted for large number of programming languages and models, system configurations (SoC type, kernel version, etc.), and for various disturbing system loads. Therefore, the primary outcome of this research is a detailed workflow of such evaluation, based on which we plan to implement an automated measurement system.

Nuno Rodrigues, Luís Rosado, Pedro M. Ramos
Portable Embedded System for Contactless Measurement of Material Conductivity

Non-Destructive Testing (NDT) of metallic materials such as aluminium is a growing area that requires novel sensing solutions. From the several NDT methods, eddy currents testing is the preferred to inspect metallic parts and welding joints searching for flaws and other material discontinuities. Eddy currents sensors are devices capable of contactless assessment with high-resolution measurements of any conductive target. High resolution and tolerance in dirty environments make eddy currents sensors indispensable in modern industrial operations. One of the uses of eddy currents sensors is to measure electrical conductivity. The value of the electrical conductivity of a metal depends on its chemical composition and crystalline structure. This work presents the development, implementation and characterization of a compact embedded system for contactless metal conductivity measurements.

G.W. C. Wijayasundara, Hyung-Kew Lee, Seung-Nam Park, Hehree Cho, Mun-Seog Kim
Linearity Evaluation of High Speed Sampling Delta- Sigma ADC Board

High-speed sampling delta-sigma ADC boards become popular in scientific and metrology researches these days and its demands on the evaluation and calibration are increasing. The aim of this research is to investigate linearity deviation for delta-sigma ADCs, NI-5922 on PXI platform, to input signal. Here, we developed a system to measure the linearity error of ADC adopting a reference sampling voltmeter and a dummy waveform generator. With this system, we evaluated the linarity error for three units of NI-5922 boards, which were combined with three different chassis based on the PXI and the PXI Express platforms. We found that the linearity error depends on the type of the PXI platforms comined with the ADC boards.

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