Stanislav Slovak

Determination of the quality of frying oil based on UWB impedance spectrometer

The goal of this paper is to draw attention to the possibility of detecting discarded vegetable oil, used at the fryer, via a UWB integrated reflectometer, which enables wideband sensing from “almost DC” to 9 GHz. An integrated reflectometer allows online monitoring of the differences between pure oil, and oil under measurement. For oil quality sensing, a test was proposed which utilizes a structure consisting of a microstrip sensor, an UWB reflectometer, an UWB radar system with an A/D converter, a source clock signal (CLK) and a computer for processing and evaluating results.

Robot vision ultra-wideband wireless sensor in non-cooperative industrial environments

In this article, the ultra-wideband technology for localization and tracking of the robot gripper (behind the obstacles) in industrial environments is presented. We explore the possibilities of ultra-wideband radar sensor network employing the centralized data fusion method that can significantly improve tracking capabilities in a complex environment. In this article, we present ultra-wideband radar sensor network hardware demonstrator that uses a new wireless ultra-wideband sensor with an embedded controller to detect and track online or off-line movement of the robot gripper. This sensor uses M-sequence ultra-wideband radars front-end and low-cost powerful processors on a system on chip with the advanced RISC machines (ARM) architecture as a main signal processing block. The ARM-based single board computer ODROID-XU4 platform used in our ultra-wideband sensor can provide processing power for the preprocessing of received raw radar signals, algorithms for detection and estimation of target’s coordinates, and finally, compression of data sent to the data fusion center. Data streams of compressed target coordinates are sent from each sensor node to the data fusion center in the central node using standard the wireless local area network (WLAN) interface that is the feature of the ODROID-XU4 platform. The article contains experimental results from measurements where sensors and antennas are located behind the wall or opaque material. Experimental testing confirmed capability of real-time performance of developed ultra-wideband radar sensor network hardware and acceptable precision of software. The introduced modular architecture of ultra-wideband radar sensor network can be used for fast development and testing of new real-time localization and tracking applications in industrial environments.

Electrically short active antennas for M-sequence UWB systems

Antennas are key elements of every radio device. As their dimensions are proportional to the operational wavelength, they are becoming the limiting element for handheld devices operating at lower frequencies. In this article, the novel concept of active receiving and transmitting antennas is proposed for an M-sequence UWB (ultra wide band) ground penetrating radar (GPR) to minimize dimensions, complexity and costs of the antennas. Radiation principles of selected electrically short antennas are described and appropriate active circuits are designed as well. Their performance is verified by measurements in the UWB system. Using the electrically short antennas with active circuits designed in this work, 8 dB higher received signal level has been achieved in lower part of the frequency band while reducing costs, dimensions and weight of the antennas approximately 10-fold.

New ultra-wideband sensor system for measuring the properties of liquid materials

The aim of this paper is to show non-commercial and low-cost measurement methods, which can detect and monitor the composition of the fluid or additives directly in the production process, thus also showing measurement methods that allow easy and continuous collection and evaluation of data, ideally in real time. The paper describes two methods of measurement, reflective and transmission that use UWB sensor which generates an M-sequence of order 9, accompanied by the CPW probes. In the experiments three different configurations of CPW probes ware used, adapted for measurements in a closed system where the fluid flows. The measurements resulted in the selection of a suitable implementation of the CPW probe affects the results of these measurements. For that reason the various fluid samples evaluated experimental measurements with properly chosen CPW probe, the characteristics of which have been adopted as a compromise to measure in the widest frequency range. Samples of liquid were distilled water represented by two different manufacturers, and sample with added defined concentration of lactose.

Integrated wideband reflectometer with on-line reference measurement capability

The aim of the paper is to show the novel integrated reflectometer designed for the wideband sensing in the arbitrary frequency band up to 9 GHz and beginning at the DC. The reflectometer utilizes pseudo noise (PN) based single chip transceiver with one transmitter and two wideband sub-sampling receivers including integrated directional couplers. The topology with the two monolithically realized receive channels allows on-line monitoring of the difference between the reference, i.e. well-known medium, and the medium under test (MUT). Simple experiment with moist and dry grain shows the early competence of the approach for the process or material monitoring purposes.