Branislav Vuksanovic

WIDEBAND SOUNDER FOR DYNAMIC AND STATIC WIRELESS CHANNEL CHARACTERISATION: URBAN PICOCELL CHANNEL MODEL

This paper presents a high speed configurable FPGA-based wideband channel sounder with signal bandwidths up to 200 MHz and results of a study of dynamic urban picocell channel. The use of FPGA allows the sounder to be adaptable for measurements in different scenarios. Adaptable options include changes to the waveform, bandwidth, channel sampling rate and real-time averaging to improve signal-to-noise ratio in weak signal conditions. The implemented architecture has led to a 70% reduction in size and weight compared to sounders in use elsewhere making it ideal for mobile channel measurements. The study of an urban picocell channel has shown that dynamic variation due to automotive traffic introduces average signal strength fades of up to 5 dB but causes frequency selective fading with depths of up to 40 dB. Existing channel models assume antenna heights of more than 6 m and path lengths of more than 30 m. Therefore there is a need for shorter path models and this paper proposes a linear picocell channel model for static and dynamic urban environment.

Original articles: An FPGA-based approach to the automatic generation of VHDL code for industrial control systems applications: A case study of MSOGIs implementation

When used for specifying control systems, system level design tools such as Xilinx System Generator (XSG) allows the use of Simulink for designs based on Field Programmable Gate Arrays (FPGAs). This increases productivity by reducing the wide gap between control system designers and FPGA-based implementations. However, there is still a need for new methods to bridge the gap since a direct implementation from XSG may not be an optimal solution when constraints are imposed. This is particularly true for resource-dominated circuits, where the number of operational units exceed the number of available resources. This paper presents both a methodology and a tool aimed at automatically reducing the required resources, in particular in systems where the required sampling period is greater than the computation time delay. An automatic process of converting XSG specifications into efficient Very High Speed Integrated Circuit Hardware Description Language (VHDL) code is described. The process mainly involves customized fixed-point hardware definition, Data Flow Graph (DFG) extraction, resource-constrained and latency-constrained scheduling and VHDL specification of the system, inter alia. This solution considerably improves on the results obtained by XSG.

ECG based system for arrhythmia detection and patient identification

In this paper a system to detect arrhythmia by automatically classifying normal and two types of abnormal ECG signals is presented. ECG signals are first pre-processed to reduce the baseline drift, noise and other unwanted components that might be present in the signal. The autoregressive modelling of the signals is then applied to extract small set of signal features - coefficients of autoregressive (AR) signal model. Groups of extracted AR parameters for three different ECG types are well separated in feature space which provides for perfect signal classification and heart condition detection for every ECG signal from the test set. In order to assess the accuracy of developed technique for individual patient identification, feature sets are extended with additional parameter - power of AR modelling error. A new ECG based biometric system is proposed and initial patient recognition results presented in the conclusion of the paper.

Discarding Unwanted Features from GPR Images Using 2DPCA and ICA Techniques

Measurements obtained using ground penetrating radar (GPR) can suffer from large amount of noise and clutter. Current methods, such as time gating and background averaging can be applied to remove reflections from air-ground interface but do not perform well when removal of unwanted clutter signals originating from the objects other than the target is needed. This work describes and evaluates performance of two signal processing techniques - two-dimensional Principal Component Analysis (2DPCA) and Independent Component Analysis (ICA) in this kind of tasks. Experimental data using simple geometric shapes under laboratory conditions, containing strong clutter components are used to demonstrate the effectiveness of the proposed techniques.

Clutter removal techniques for GPR images in structure inspection tasks

This document analyses the performance of subspace signal processing techniques applied to ground penetrating radar (GPR) images in order to reduce the amount of clutter and noise in the measured GPR image. Two methods considered in this work are Principal Component Analysis (PCA) and Independent Component Analysis (ICA). An approach to combine those two techniques to improve their effectiveness when applied to GPR data is proposed in this paper. The experiments performed to gather GPR data and evaluate proposed algorithms are also described. The aim of undertaken experiments is to replicate conditions found in water reservoirs where cracks and holes in the reservoir foundations and joints cause excessive water leakages and losses to water companies and the UK economy in general. Performance of implemented algorithms is discussed and compared to the results achieved by a highly skilled human - GPR image analyst.

A New Approach to Detection of Systematic Errors in Secondary Substation Monitoring Equipment Based on Short Term Load Forecasting

In recent years, Secondary Substations (SSs) are being provided with equipment that allows their full management. This is particularly useful not only for monitoring and planning purposes but also for detecting erroneous measurements, which could negatively affect the performance of the SS. On the other hand, load forecasting is extremely important since they help electricity companies to make crucial decisions regarding purchasing and generating electric power, load switching, and infrastructure development. In this regard, Short Term Load Forecasting (STLF) allows the electric power load to be predicted over an interval ranging from one hour to one week. However, important issues concerning error detection by employing STLF has not been specifically addressed until now. This paper proposes a novel STLF-based approach to the detection of gain and offset errors introduced by the measurement equipment. The implemented system has been tested against real power load data provided by electricity suppliers. Different gain and offset error levels are successfully detected.

Multichannel Filtered-Inverse Least Mean Square Algorithms - Development and Analysis

This paper describes the algorithms for multichannel active noise control systems based on adaptive filtered- inverse least-mean-square algorithm (FILMS). General mathematical model of multichannel FILMS (MFILMS) algorithm is developed based on the cross-cancelling structure of the inverse plant used in the algorithm and the update equations for this setup are derived. This approach is robust but its computational load grows rapidly with the number of implemented channels. Methods to develop more efficient realizations using partial updates of the adaptive filters in the system and suppression of the cross-cancellation effects in the inverse plant are described and analyzed in this paper. Simulations are performed to demonstrate the effectiveness of each method and computational loadings are estimated for each derived version of multichannel algorithm.

Load forecasting via detrending and deseasoning

Load forecasting is a term usually applied to describe a process of estimation or prediction of future energy demand for a certain distribution grid or part of a grid. Large number of different methods and techniques used for load forecasting have been developed in the past and new and improved methods are regularly being reported in research literature. This paper describes one of traditional load forecasting approaches based on autoregressive moving average (ARMA) modelling of load demand time-series (TS). However, it reconsiders each step in this process and proposes some new procedures to improve and clarify the whole method. Effectives of described approach is demonstrated using energy consumption measurements recently recorded at substations in central London area.

Measurement and preliminary analysis of powertrain vibrations in vehicle production environment

In a vehicle production environment, obtaining information on the condition of the assembled vehicle, allows for increased quality while minimizing rework minutes at the same time. The cost of this information is associated with additional time in production, increasing the overall cost of the vehicle. The focus of this paper is development of a system for contactless measurement and investigation of vibrations present in the vehicle and the Rolling Road vehicle testing facility as a mean of identifying failures or degradation in the vehicle or testing facility. Measurements are performed using a contactless Laser Vibrometer based system which facilitates capturing the vibrations without interfering with the vehicle and other standard testing procedures. Signal conditioning and analysis methods are applied to measured vibration signals in an attempt to detect irregularities and determine their transient characteristics from the captured signals. Data analysis techniques employed in this initial trial of the system include Short Time Fourier and Wavelet Transforms. Proposed testing method including experimental setup, captured signals and some preliminary analysis results are discussed in this paper.

Resonant modes analysis in power systems algorithms and Matlab GUI

This paper describes a set of algorithms used to detect and analyse resonant modes present in the oscillatory type signals measured in power systems using Wide Area Measurement System (WAMS) technology. To enable easier analysis and extraction of the main signal parameters - frequency, amplitude and damping, described algorithms have been implemented and tested using Matlab based GUI program. Algorithms performance, operation of developed GUI and some initial results are presented in this paper indicating the potential use of this approach and described methods in large, interconnected power systems of today.