490 research outputs found

    Radio Sensor for Monitoring of UMTS Mobile Terminals

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    Relatively simple and low-cost radio sensor for monitoring of 3rd generation (3G) UMTS mobile terminals (i.e., phones) has been designed and practically tested. The main purpose of this sensor is to serve as an extending module that can be installed into systems used for monitoring of standard 2nd generation (2G) GSM and DCS mobile phones in highly guarded buildings and areas. Since the transmitted powers of UMTS mobile terminals can be very low in relation to GSM and DCS specifications, the new UMTS sensor is based on a highly sensitive receiver and additional signal processing. The radio sensor was practically tested in several scenarios representing worst-case mobile terminal - base station relations. The measured detection ranges attain values from approx. 11 m inside of rooms to more than 30 m in corridors, which seems to be sufficient for the expected application. Results of all performed tests correspond fairly well with the presented theoretical descriptions. An extended version of the radio sensor can be used for monitoring of mobile terminals of all existing voice or data formats

    Noise Parameters of CW Radar Sensors Used in Active Defense Systems

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    Active defense represents an innovative way of protecting military vehicles. It is based on the employment of a set of radar sensors which detect an approaching threat missile and activate a suitable counter-measure. Since the radar sensors are supposed to detect flying missiles very fast and, at the same time, distinguish them from stationary or slow-moving objects, CW Doppler radar sensors can be employed with a benefit. The submitted article deals with a complex noise analysis of this type of sensors. The analysis considers the noise of linear and quasi-linear RF components, phase-noise of the local oscillator as well as the noise of low-frequency circuits. Since the incidence of the phase-noise depends strongly upon the time delay between the reference and the cross-talked signals, a new method of measuring noise parameters utilizing a reflecting wall has been developed and verified. The achieved results confirm potentially high influence of the phase-noise on the noise parameters of the mentioned type of radar sensors. Obtained results can be used for the analysis of noise parameters of the similar but even more complex sensors

    A Novel Approach to Face Recognition using Image Segmentation based on SPCA-KNN Method

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    In this paper we propose a novel method for face recognition using hybrid SPCA-KNN (SIFT-PCA-KNN) approach. The proposed method consists of three parts. The first part is based on preprocessing face images using Graph Based algorithm and SIFT (Scale Invariant Feature Transform) descriptor. Graph Based topology is used for matching two face images. In the second part eigen values and eigen vectors are extracted from each input face images. The goal is to extract the important information from the face data, to represent it as a set of new orthogonal variables called principal components. In the final part a nearest neighbor classifier is designed for classifying the face images based on the SPCA-KNN algorithm. The algorithm has been tested on 100 different subjects (15 images for each class). The experimental result shows that the proposed method has a positive effect on overall face recognition performance and outperforms other examined methods

    Errors in Measurement of Microwave Interferograms Using Antenna Matrix

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    New antenna matrices for both scalar and vector measurement of microwave interferograms for the frequency 2.45 GHz were developed and used for an analysis of sources of measurement errors. Influence of mutual coupling between individual antennas in an antenna matrix on a measurement of microwave interferograms, particularly on a measurement of interferogram minimum values, was studied. Simulations and measurements of interferograms, proposal of a new calibration procedure and correction method are presented. Influence of differences in radiation patterns of individual antennas of an antenna matrix on a measurement of microwave interferograms was studied as well

    ASTRONOMICAL GLASS PLATE NEGATIVES: MONITORING OF EMULSION LAYER DETERIORATION

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    One of the techniques for making photographic negatives most used in the history of photography were gelatin glass plates. This technique was used not only in the artistic field but also and mainly in the scientific field. The main period when glass plate negatives were used in astronomy was between 1890–1980. There are over 7 million of these negatives all over the word and they carry valuable historical scientific data. However, during the long-term storage of this material, deterioration of the emulsion (picture) layer and/or the support (glass) layer has occurred. In this paper we report on our preliminary results from an analysis of the yellowing of the emulsion layer and of gold micro-spots. Both phenomena worsen the readability of the information in the photograph, and it is necessary to prevent their formation, which is why we need to know as much as possible about their origin

    TRL-based Measurement of Embedded Circuits in Microwave Printed Circuit Boards Including Frequency Conversion

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    The paper deals with the measurement of individual components or circuits embedded in more complex radio frequency (RF) or microwave printed circuit board (PCBs). Since no standard RF measurement enables the direct parallel connection of an analyzer to the boards being tested, individual components are often measured by destructively cutting manufactured boards and by attaching the RF connectors to the concerned parts. This article shows that this problem, thanks to suitable calibration standards that have been designed and manufactured, can be solved by vector measurements and a TRL calibration process. The measurements also work when the boards to be measured include frequency conversion. The applicability of the developed method has been verified by practical measurements and its accuracy influenced by variations of the parameters of the surrounding circuits has been investigated by an uncertainty analysis

    Gully Erosion of Coastal Plain Sediments of SE Nigeria - Final Summary Technical Report

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    Coastal plain sediments of SE Nigeria are prone to rapid and extensive gullying. Gully advances of 157m in length, 50m in width, and 5m in depth per year have been measured, and have cut through road, isolated villages, disrupted water supplies, and caused major landslides. The gullying rates have increased in recent years because of increased population pressures and resultant vegetative cover denudation and poor drainage channelization. Studies were carried out in nine different sites over four different gully-prone formations. The gully-prone areas are underlain by lateritic coastal sands of very specific geotechnical properties, such as similar grain size distribution, uniformity, and dispersivity. Correlations indicate that the gully advance and dispersion rate is governed mostly be the sands' grain size distribution and uniformity. The Ca0, K20, Mn0 and Mg0 content of the weak lateritic cements also have a significant statistical relationship to the gullying process

    A Novel System for Non-Invasive Method of Animal Tracking and Classification in Designated Area Using Intelligent Camera System

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    This paper proposed a novel system for non-invasive method of animal tracking and classification in designated area. The system is based on intelligent devices with cameras, which are situated in a designated area and a main computing unit (MCU) acting as a system master. Intelligent devices track animals and then send data to MCU to evaluation. The main purpose of this system is detection and classification of moving animals in a designated area and then creation of migration corridors of wild animals. In the intelligent devices, background subtraction method and CAMShift algorithm are used to detect and track animals in the scene. Then, visual descriptors are used to create representation of unknown objects. In order to achieve the best accuracy in classification, key frame extraction method is used to filtrate an object from detection module. Afterwards, Support Vector Machine is used to classify unknown moving animals

    The Optical Transient Search in the Bamberg Southern Sky Survey: Preliminary Results

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    A large fraction of gamma-ray bursts temporarily emit optical light, i.e. optical afterglows and optical transients. So far, optical transients have only been detected after related gamma-ray satellite detection. However, taking into account their optical magnitudes at maximum light, these objects should be detectable in various historical and recent optical surveys, including the photographic sky patrol. Here we report on an extended study based on blink-comparison of 5004 Bamberg Observatory Southern Sky Patrol Plates performed within a student high school project (Jugend Forscht)
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