Showing papers in "Iete Journal of Research in 2010"

Electrically Small Patch Antenna Loaded with Metamaterial

Abstract: In this paper, the authors present a new planar metamaterial loaded electrically small microstrip patch antenna. The rectangular microstrip patch antenna is loaded by metamaterial using planar square spilt ring resonators (SRRs). The unloaded rectangular microstrip patch antenna resonates at 23 GHz, whereas after loading it by metamaterial, the same antenna resonates at 9.51 GHz. In loaded condition, the resonant frequency of rectangular microstrip patch antenna reduces due to magnetic coupling. The dimensions of the antenna structure are 0.161λ × 0.192λ. Using the Chu limit, the size of the antenna comes to ka = 0.775, thus, satisfies the condition of an electrically small antenna (ka < 1). The antenna exhibits an impedance bandwidth of 512 MHz at a resonant frequency of 9.51 GHz. The calculated radiation Q rad is 18.86 which is larger than Qchu minimum, that is Qchu, = 3.43. The gain and directivity of this antenna structure are 3.2 dBi and 7.8 dBi, respectively. The proposed antenna structure i...

Unity/Variable-gain Voltage-mode/Current-mode First-order All-pass Filters Using Single Dual-X Second-generation Current Conveyor

Abstract: In this paper, two new general topologies for realizing voltage-mode (VM)/current-mode (CM) first-order all-pass Alter transfer functions (TFs) are presented. The proposed topologies use single dual-X second-generation current conveyor (DXCCII) and three impedances Z1, Z2 and Z3. Based on the selection of Z1, Z2 and Z3, new VM and CM all-pass Alters with unity or variable gains are obtained. The proposed VM/CM filters have high-input/high-output impedances which provide easy cascading at their input/output terminals, respectively. Non-ideal gain and parasitic impedance effects, associated with actual DXCCII implementation, on the performance of the developed topologies are also included. Finally, simulation program with integrated circuit emphasis (SPICE) simulation results based on level 49, 0.25 μm TSMC complementary metal-oxide-semiconductor (CMOS) technology parameters are given to confirm the theory.

Comparing the Performance of Ultrasonic Liver Image Enhancement Techniques: A Preference Study

Abstract: This is a preliminary study and the objective of this study has been to compare the performance of some of the primitive and fundamentally different post acquisition image enhancement algorithms as applied to ultrasound (US) liver images. Such a comparison would help to decide as to which algorithm could be useful for clinicians, and in evaluating the role of US liver image enhancement in a soft-copy environment. In this study, 10 US liver images were taken, and 5 fundamentally different and widely employed image enhancement techniques were applied on these images. As the principal objective of image enhancement is to obtain an image with a high content of visual detail, a multipoint rank-order method was used to identify small differences or trends in observations. Among the different algorithms, the morphological Altering outperformed other techniques. The images with diffused liver diseases had a preference of 76% and the images with cystic masses had a preference of 67%. Wavelet-based Altering...

Two-scale Auditory Feature Based Non-intrusive Speech Quality Evaluation

Abstract: This paper proposes a novel two-scale auditory feature based algorithm for non-intrusive evaluation of speech quality. The neuron firing probabilities along the length of the basilar membrane, from an explicit auditory model, are used to extract features from the distorted speech signal. This is in contrast to previous methods, which either use standard vocal tract based features, or incorporate only some aspects of the human auditory perception mechanism. The features are extracted at two scales, namely a global scale spanning all voiced frames in an utterance, and a local scale spanning voiced frames from contiguous voiced segments in the utterance. This is followed by a simple information fusion at the score level using Gaussian Mixture Models (GMMs). The use of an explicit auditory model to extract features is based on the premise that similar processing (in a qualitative sense) happens in human speech perception. In addition, auditory feature extraction at two scales incorporates the effects ...

Doppler-bearing Passive Target Tracking Using a Parameterized Unscented Kalman Filter

Abstract: Target motion analysis (TMA) using conventional passive bearing together with frequency measurements is explored. This approach offers one tactical advantage over the classical bearings-only TMA. It makes the ownship maneuver superfluous. In this paper, TMA is carried out using an unscented Kalman filter (UKF). The inclusion of range, course, and speed parameterization is proposed in the UKF target state vector to obtain the convergence of the solution fast. Finally the results of one scenario in Monte-Carlo simulation are presented.

Biosignal Denoising via Wavelet Thresholds

Abstract: Biopotential signal is an electric quantity (voltage or current or field strength), caused by chemical reactions of charged ions. In experimental data collection, a signal of data points does not represent a perfect theoretical expectation. It always contains some noise due to various consequences. Denoising of the ECG wave and MRI image based upon the discrete wavelet transform (DWT) and discrete stationary wavelet transform (SWT) with different threshold techniques has been applied and presented in this paper.

A Statistical Approach for Fault Diagnosis in Electrical Machines

Abstract: Condition monitoring is a technique of sensing the health of electrical machines. Analysis of the monitoring data quantifies the condition of the machine, so that faults can be detected and diagnosed at the incipient stage itself. Machine vibrations are known to carry information on most of the faults. Vibration response measurements yield a great deal of information concerning faults within rotating machines. Studies show that bearings are the major contributors to an onset of a fault. The aim of this paper is to compare the variations of a time domain signal of machine vibrations when the bearing is (a) healthy (fault free), (b) having a fault in the outer race, and (c) having a fault in the inner race. The statistical approach is used to investigate and classify the faults. The well-known frequency domain analysis is carried out to verify results of the statistical analysis. The proposed analysis technique implies a clear indication of the changes that occur even when a fault is at an incipient...

Time and Angle of Arrival Statistics of Mobile-to-mobile Communication Channel Employing Dual Annular Strip Model

Abstract: In this paper, a generalized channel model for mobile-to-mobile communication based on the single bounce geometry-based channel modeling techniques has been proposed and analyzed. The model assumes the scatterers to be present in annular strips around the transmitting and the receiving mobile stations. Time of arrival and angle of arrival statistics, being two important channel parameters, have been derived and verified through computer simulations.

Implementation of Cascade Multilevel Inverter-based STATCOM

Abstract: This paper deals with the real time implementation of 11-level cascade multilevel inverter-based STATCOM using personal computer (PC) and ADD-ON cards for power system voltage control at the point of common coupling. Complete hardware and software development procedures have been explained in depth for direct as well as indirect control schemes. Experimental results are presented and it is shown that voltage control is achieved using cascade multilevel inverter based STATCOM, thus verifying the very basic purpose of STATCOM. Real time implementation using PC-based control technique has certain merits over digital signal processor based implementation, and some of these merits are high processing speed and low cost of implementation; therefore, PC-based implementation can be used in industry as well as for utility applications.

Modeling and Compensation of Periodic Nonlinearity in Two-mode Interferometer Using Neural Networks

Abstract: The periodic nonlinearity in nano-metrology systems based on heterodyne interferometers is the most important limitation to the accuracy of displacement measurement. It is mainly produced due to the polarization-mixing and frequency-mixing. In this paper, a new approach based on an ensemble of neural networks for modeling and compensation of nonlinearity in a high-resolution laser heterodyne interferometer is presented. We model the periodic nonlinearity arising from elliptical polarization and non-orthogonality of the laser polarized light based on the neural network approaches, including the multi-layer perceptrons and radial basis function as single neural networks and stacked generalization method as ensemble of neural networks. It is also shown that by using the stacked generalization method, the primary periodic nonlinearity of 1.3 nm is significantly compensated by a factor of 168.

A DSP-based Integrated Hardware Set-up for a DSTATCOM: Design, Development, and Implementation Issues

Abstract: The paper describes the design, development, and implementation issues of a digital signal processor-based integrated hardware set-up for a distribution static compensator (DSTATCOM). A detailed documentation revealing all the design aspects of the important building blocks of the set-up is presented. The transducer, signal conditioning, synchronizing, blanking, protection, optoisolation, and power supply circuits are constructed and assembled to form a prototype laboratory model. In the present work, an H-bridge voltage source inverter-based DSTATCOM has been realized. The efficacy of this arrangement is demonstrated by conducting experiments and the results are discussed.

Multimodal Function Optimization Using Synchronous Bacterial Foraging Optimization Technique

Abstract: The paper presents an improved variant of bacterial foraging optimization (BFO) named as Synchronous Bacterial Foraging Optimization (SBFO). The proposed SBFO is used to optimize multimodal and high dimensional functions. As all the bacteria update their information simultaneously, it has been named synchronous. A mutation operator proposed in this paper performs the global search. In SBFO, all bacteria process information independently in the same generation; hence parallel computers can be used to evaluate fitness values. The performance of SBFO is validated on a set of seven benchmark functions i.e. Sphere, Rosenbrock, Rastrigin, Griewank, Ackley, Schaffer’s, Shekel’s Foxholes. The results are compared with other published methods such as classical BFO, hybrid BFO (BSO), swarm-based algorithms, differential evaluation and Ashaker. The simulation results on benchmark functions show that the proposed optimization is capable of producing good quality global optima as compared to the above mentione...

Novel Circuit Technique for Reduction of Leakage Current in Series/Parallel PMOS/NMOS Transistor Stack

Abstract: Stacking of MOS transistors is used for minimization of leakage current in nano-scale Complementary Metal Oxide Semiconductor (CMOS) circuits. Stack arrangement of P-Channel Metal Oxide Semiconductor (PMOS) is preferred over N-Channel Metal Oxide Semiconductor (NMOS) because value of leakage current in PMOS is lesser as compared to NMOS. It results as the mobility of holes in PMOS is lesser than mobility of electrons in NMOS. This paper leads us to an observation of leakage current consumption by series/parallel combination of PMOS/NMOS transistors. This observation results in the development of novel circuit technique for reduction of leakage current in series/parallel PMOS/NMOS assembly. The effect of VGS, VDS, VSB and intermediates node voltages is also addressed. The proposed circuit is simulated for Model file BSIM 3 Ver.3.1, TSMC 0.18 μ technology using Spice© simulator.

Performance Evaluation of Three Different Configurations of DSTATCOM with Nonlinear Loads

Abstract: This paper deals with three different configurations of Distribution Static Synchronous Compensator (DSTATCOM) for distribution system. Detailed analysis, modeling, design and control are discussed for each configuration of DSTATCOM. MATLAB based models are developed for improving power factor/voltage regulation and neutral current compensation. Results show a marked reduction in total harmonic distortion (THD) of supply current levels when applied to nonlinear loads. Dynamics of systems are reported with sudden load addition or removal and performance of system is demonstrated in detail.

Decoupled Solid State Controller for Asynchronous Generator in Pico-hydro Power Generation

Abstract: This paper deals with a decoupled solid state controller (DSSC) for an isolated asynchronous generator (IAG), used in constant power pico-hydro power generation for feeding three-phase four-wire loads. The proposed DSSC is used to control the voltage and frequency of the IAG in the decoupled manner. This DSSC is a combination of a voltage regulator (VR) for regulating the voltage and a conventional electronic load controller (ELC) for controlling the active power to regulate the frequency. The VR is realized using a zigzag/three-single-phase transformer and six-leg insulated gate bipolar transistors (IGBTs)-based current controlled voltage source converter (VSC) with a capacitor on its DC bus and an ELC is a combination of a three-phase diode bridge rectifier with a chopper switch and an auxiliary load. The proposed DSSC with an isolated generating system is modeled and simulated in MATLAB along with Simulink and power system blockset (PSB) toolboxes. The simulated results of the IAG-DSSC system a...

Effect of PAPR Reduction Techniques on the Performance of MB-OFDM UWB in Wireless Communications

Abstract: Multiband orthogonal frequency division multiplexing (MB-OFDM) is an efficient approach for ultra-wideband (UWB) wireless communication applications. One major difficulty of MB-OFDM UWB signal is its large peak-to-average power Ratio (PAPR). The high PAPR limits its capacity due to the distortion caused by the nonlinear characteristics of both the analog-to-digital converter (ADC) and high-power amplifier (HPA). Hence, it is necessary to reduce the PAPR of MB-OFDM UWB signals. Several techniques have been reported in the literature for PAPR reduction in OFDM. These techniques can also be extended for PAPR reduction in MB-OFDM UWB signals. However, comparative performance evaluation of these techniques for PAPR reduction in MB-OFDM UWB signals is lacking in the literature. Hence, in this paper, four techniques, namely, filtering after clipping, turbo coding of clipped signals, tunable predistorter, and active constellation extension are extended for PAPR reduction of MB-OFDM UWB signals and their p...

Estimation of Total Electron Content and Instrumental Biases of Low Latitude Global Positioning System Stations Using Kalman Filter

Abstract: In order to achieve the required navigation accuracy for satellite based augmentation system (SBAS) applications, the ionospheric total electron content (TEC) must be accurately estimated. However, measurements of TEC from the Global Positioning System (GPS) observables are corrupted by instrumental delay biases of satellites and receiver, measurement noise and multipath errors. In this investigation, an algorithm based on the Kalman filter is developed for the estimation of TEC and instrumental biases, using single station data in contrast to multi-station technique reported elsewhere. The initial state of receiver bias in the Kalman filter is chosen using a modified fitted receiver bias (FRB) method. The estimated instrumental biases for several equatorial and low latitude stations in the International GNSS Service (IGS) and GPS Aided Geo Augmented Navigation (GAGAN) network show significant improvement.

Performance Analysis of the 2nd Order Phase Lock Loop when Phase Modulation is Added to the Voltage Controlled Oscillator

Abstract: A classic phase lock loop (PLL) consists of a voltage controlled oscillator (VCO), a phase detector (PD) or phase comparator and a loop filter. The characteristics of a PLL are well established. A modification is introduced in the VCO in the name of phase modulation input along with its original frequency modulation input. This paper analyzes the characteristics such as damping factor, relative stability, noise bandwidth, transient behavior in this modified version of 2nd order PLL and compares them with the classic PLL.

A Novel Semi-blind Channel Estimation Scheme for Rayleigh Flat Fading MIMO channels (joint LS estimation and ML detection)

Abstract: In this article, the training-based channel estimation (TBCE) and semi-blind channel estimation (SBCE) schemes in Rayleigh flat fading multiple-input multiple-output (MIMO) channels are investigated. First, least squares (LS), linear minimum mean square error (LMMSE), maximum likelihood (ML), and maximum a posteriori (MAP) channel estimators are presented and simulated. Owing to faster processing and lower bit error rate (BER), the LS estimator is the proper choice for both TBCE and SBCE-ML. It is illustrated that when the number of transmitter and/or receiver antennas increases, the performance of both TBCE and SBCE-ML schemes significantly improves. In addition, Alamouti coding has more effect on the performance of SBCE-ML rather than TBCE. Comparing LS-based TBCE and LS-based SBCE-ML, the simulation results introduce the most appropriate channel estimation method that uses an iterative algorithm. This new proposed method is based on LS estimator and ML detector. Simulation results of this inves...

Performance of Microstrip Low-Pass Filter on Electromagnetic Band Gap Ground Plane

Abstract: In this work, the performance characteristics of a printed low-pass Alter (LPF) were analyzed on an electromagnetic band gap (EBG) ground plane. A ninth order Chebyshev LPF was designed at 2.44 GHz cut-off frequency using Stepped Impedance Resonator (SIR) method. The simulation results show that the EBG pattern of rectangular slots etched on the ground plane and located offset from the center line not only offers an improved stopband characteristic but also reduces the overall size of the Alter. Finally, a prototype model was developed based on the results obtained from the simulation and tested. The simulated and experimental results show good agreement.

A CMOS 2-11 GHz Continuous Variable Gain UWB LNA

Abstract: In this paper, a new CMOS variable gain low noise amplifier (VG LNA) with continuous gain variation for 2–11 GHz employing a resistance feedback current reuse stage and a cascode stage is presented. By controlling the transimpedance feedback resistor of the first stage and the bias current of the second stage, a continuous gain tuning range of 26 dB is achieved without influencing the input match and output match. The VG LNA is simulated based on the TSMC 0.18 μm CMOS process and shows the following performance at the highest gain mode: S11 is less than -10 dB from 3 to 10.2 GHz, and S22 is less than -18 dB from 2 to 11 GHz. In the total 2–11 GHz frequency range, the gain is more than 17 dB, and the noise figure is less than 3.8 dB, while drawing 7.57 mA from 1.4 V supply voltage.

Systematic Width Determination for the Design of Power-Constrained Noise Optimization Inductively Degenerated Low Noise Amplifier

Abstract: Systematic width determination for the inductively degenerated low noise amplifier (IDLNA) was implemented using power-constrained noise optimization (PCNO) technique. Using drain current for short channel equation, the power dissipated (PD) as a function of gate overdrive (VOV) expression was derived. This expression was further arranged to represent PD as a function of input stage quality factor (QS). The two relations were translated into contours which were generated at fixed noise figure (NF). By means of manipulating the same equations, the NF as a function of QS was derived. The contours were generated using the parameters specified for Silterra’s 0.18 μm CMOS process for Wideband-Code Division Multiple Access (W-CDMA) application. The PD versus VOV contours show that the NF of the LNA can be improved if PDis increased. These contours also illustrate that for a W-CDMA with a requirement of below 2.5 dB of NF, the VOVis in the range of 46–115 mV. The PD and NF versus QS contours show that mi...

Efficient Median Filter for Restoration of Image and Video Sequences Corrupted by Impulsive Noise

Abstract: Various switching-based median filters have been proposed in the literature for restoration of extremely corrupted images and video sequences by impulsive noise. Among these, switching median filters with boundary discriminative noise detection (BDND) are very effective and outperform all the previously proposed median-based filters. However, the calculation is very time-consuming. Hence, in this paper, a median filter with an efficient BDND (EBDND) is proposed for denoizing image and video sequences corrupted by impulsive noise. The proposed EBDND uses a faster sorting algorithm both in noise detection and adaptive filtering stages for the restoration of image and video sequences contaminated by impulse noise. For motion estimation of the video sequence, block-matching technique is used. The performance of the proposed EBDND is demonstrated through computer simulations in comparison with the BDND method.

Chip Equalized Adaptive Rake Receiver for DS-CDMA UWB Systems

Abstract: Conventional Rake receiver is a popular and effective method of utilizing the diversity offered by a DS-CDMA and multipath communication channel. The proposed Rake receiver is useful for suppression of multiple access interference in a multipath channel. The receiver works on chip level equalization on each Rake finger to cancel multi-access interference. Simulation results show that the convergence, diversity gain and bit error probability performance of the proposed receiver is much better than conventional adaptive Rake receiver in multipath channels.

Power Quality Improvement in Switched Mode Power Supplies Using Autoconnected Transformer Based 9-Phase ac-dc Converters

Abstract: Switched Mode Power Supplies (SMPS) of medium power ratings are extensively used in heating, welding and telecommunication power supply applications. Invariably, they use a 3-phase ac-dc converter at the front end. In this paper, different autoconnected transformer-based 9-phase ac-dc converter configurations are designed, modeled and simulated to feed such medium capacity SMPS for improving the power quality indices at the point of common coupling (PCC). The autoconnected transformer is designed suitable for producing 9-phase voltages of same magnitude and having equal phase shift. The proposed 9-phase ac-dc converters are found capable of suppressing up to 17th harmonic in the supply current along with the power factor improvement close to unity at varying loads. A set of power quality indices on input ac mains and magnetic ratings for various autoconnected transformer configurations for this SMPS are also presented so that the best converter configuration can be chosen according to the requirem...

Design and Testing of a Suitable Transceiver for Full Duplex Communication in Indoor Power Line

Abstract: Utilization of power lines (PLs) as networking options may need data/signal transfer in both half and full duplex modes. In this paper, a transceiver has been proposed, which enables full duplex connection between equipments having RJ-11 jacks, using Narrowband Transmission. The system is tested in a typical indoor PL setting for two PCs equipped with 56 kbps modems under usual household condition. Suitable couplers and line tuners are used to overcome the problems related to signal injection, reception and noise. An active hybrid having a Digital Signal Processor (DSP) -based echo canceller enables suitable signal conditioning before transmission to the PL using a dual frequency carrier (170 and 430 kHz) scheme. Variable bit rates ranging from 1.2 to 33.6 kbps have been obtained depending on the channel condition of the PL.

Vector Quantized Codebook Optimization Using Modified Genetic Algorithm

Abstract: Vector Quantization (VQ) is lossy data compression technique and has various applications. Key to VQ is a good codebook. Once the codebook size is fixed, then the mean square error (MSE) reaches a value, beyond which it cannot be reduced by using codebook generation algorithms. In this paper, we are proposing modified genetic algorithm giving the optimal value, but it depends on the initial selection of the codevectors. Hence, it takes extremely huge time to give optimal value. For demonstration, we have used codebooks obtained from Linde Buzo and Gray (LBG) and Kekre’s Fast Codebook Generation (KFCG) algorithms. It is observed that the optimal error obtained from both LBG and KFCG is almost the same, indicating that they have converged to an optimal value. From the results, it is obvious that KFCG codebook gives slightly less minimized error as compared to LBG, indicating that KFCG codebook is closer to the optimum. The proposed method is general and can be applied to any clustering algorithm.

Radio Frequency/Free Space Optical and Radio Frequency-only Wireless Sensor Networks: A Comparative Study of Performance

Abstract: Wireless sensor networks (WSNs) consist of networked sensor nodes, deployed to sense a phenomenon and report it to a base station. Sensor nodes are small and usually equipped with small batteries with limited capacity, and therefore, one of the most important design considerations for WSNs is power consumption. WSNs expend energy for communications, data processing and sensing; for commonly used RF communications this task accounts for the largest portion of power expended. Hybrid radio frequency/free space optical (RF/FSO) communications has been proposed to reduce power consumption by the sensor node, and in this paper, the performance of the RF/FSO WSN is compared against an RF-only WSN in terms of network lifetime and coverage. Results show that for the wide range of scenarios considered, the RF/FSO WSN lasts at least twice as long as its RF-only counterpart, despite providing the same level of network coverage. This paper also investigates network parameter selection for optimum RF/FSO networ...

On the Effect of Fractal Electromagnetic Band Gap on Antenna Performance

Abstract: This paper presents the design of electromagnetic band gap (EBG) structure using fractals geometry and its effect on antenna performance. The EBG structure has been designed on substrate er=4.3 and thickness h=1.53 mm. The 1st iterative EBG structure offers the surface wave suppression around 20 dB down from 2.94 to 4.58 GHz corresponds to 43.62% bandwidth. The experimental results of 2nd iterative EBG structure revealed the surface wave suppression in two bands from 2.45 to 3.36 GHz and from 8.52 to 11.02 GHz. The surface wave suppression bandwidth for both the bands is 31.325 and 25.59%, respectively. The antenna designed with the proposed EBG in same plane exhibits improvement in the bandwidth by 20.5%, gain by 2.44 dB and reduction in back lobe in comparison to antenna without EBG.

Satellite-HAP Network Supporting Multilayered QoS Routing in the Sky

Abstract: The main features of the future mobile communication systems are the provisioning of high-speed data transmissions (up to 1 Gb/s) and interactive multimedia services. For effective delivery of these services, the network must satisfy some strict quality-of-service (QoS) metrics, defined typically in terms of maximum delay and/or minimum throughput performances. According to this general vision, the integration of different layered networks play one of the most important roles in the telecommunication systems; for this reason, the paper explains the potential role of an integrated satellite-high-altitude platform (HAP) terrestrial system proposing a new multilayered inter-HAP-satellite routing (IHSR) algorithm integrated with an efficient admission control scheme in order to guarantee an adequate QoS to multimedia traffic connections. The performance of the overall architecture is evaluated through intensive simulations comparing the proposed algorithm with a previous classical routing scheme under...