This document presents a low-cost method for electromagnetic signal spectral analysis and direction finding using a two-element time-modulated antenna array and multiple signal classification (MUSIC) algorithms. It describes a prototype array constructed using quarter-wave monopoles as antenna elements switched using PIN diodes. Measurements show the array output is phase modulated depending on signal arrival angle, producing a directional pattern at the carrier frequency and null at the first harmonic. MUSIC algorithms are applied to estimate signal directions from the received signals. The method provides a low-cost alternative to conventional direction finding techniques with potential applications in wireless communications and homeland security.
Beam Steering Using the Active Element Pattern of Antenna ArrayTELKOMNIKA JOURNAL
An antenna array is a set of a combination of two or more antennas in order to achieve improved
performance over a single antenna. This paper investigates the beam steering technique using the active
element pattern of dipole antenna array. The radiation pattern of the array can be obtain by using the
active element pattern method multiplies with the array factor. The active element pattern is crucial as the
mutual coupling effect is considered, and it will lead to an accurate radiation pattern, especially in
determining direction of arrival (DoA) of a signal. A conventional method such as the pattern multiplication
method ignores the coupling effect which is essential especially for closely spaced antenna arrays. The
comparison between both techniques has been performed for better performance. It is observed that the
active element pattern influenced the radiation pattern of antenna arrays, especially at the side lobe level.
Then, the beam of the 3x3 dipole antenna array has been steered to an angle of 60° using three
techniques; Uniform, Chebyshev and Binomial distribution. All of these are accomplished using CST and
Matlab software
The presentation is about Adaptive Beamforming for high data-rate applications. Analog beamforming, which is considered a cost effective solution for consumer devices are investigated. Two adaptive analog beamforming algorithms, i.e., a well-known perturbation-based and dmr-based which overcomes the drawbacks of perturbation-based algorithm are discussed in-detail and their performance comparisons are made with the help of computer simulations. Also variation of single-port structure is considered and it's benefits are exploited with the help of modified analog beamforming algorithms.
non parametric methods for power spectrum estimatonBhavika Jethani
non-parametric methods for power spectrum estimation which includes bartlett method, welch method , blackman and tukey methods and also the comparision of all these methods
Performance Analysis of Ultra Wideband Receivers for High Data Rate Wireless ...graphhoc
For high data rate ultra wideband communication system, performance comparison of Rake, MMSE and Rake-MMSE receivers is attempted in this paper. Further a detail study on Rake-MMSE time domain equalizers is carried out taking into account all the important parameters such as the effect of the number of Rake fingers and equalizer taps on the error rate performance. This receiver combats inter-symbol interference by taking advantages of both the Rake and equalizer structure. The bit error rate performances are investigated using MATLAB simulation on IEEE 802.15.3a defined UWB channel models. Simulation results show that the bit error rate probability of Rake-MMSE receiver is much better than Rake receiver and MMSE equalizer. Study on non-line of sight indoor channel models illustrates that bit error rate performance of Rake-MMSE (both LE and DFE) improves for CM3 model with smaller spread compared to CM4 channel model. It is indicated that for a MMSE equalizer operating at low to medium SNR values, the number of Rake fingers is the dominant factor to improve system performance, while at high SNR values the number of equalizer taps plays a more significant role in reducing the error rate.
Performance Analysis of PAPR Reduction in MIMO-OFDMIJARBEST JOURNAL
Authors: Jayaraman.G1, VeeraKumar K2, Selvakani.S3
Abstract— In communication system, it is aimed to provide highest possible
transmission rate at the lowest possible power and with the least possible noise. MIMOOFDM
has been chosen for high data rate communications and widely deployed in many
wireless communication standards. The major drawback in OFDM signal transmission is
high PAPR. In previous, use clipping technique to tackle this problem. In this paper, use
EM-GAMP algorithm to reduce PAPR in considerable amount.
Beam Steering Using the Active Element Pattern of Antenna ArrayTELKOMNIKA JOURNAL
An antenna array is a set of a combination of two or more antennas in order to achieve improved
performance over a single antenna. This paper investigates the beam steering technique using the active
element pattern of dipole antenna array. The radiation pattern of the array can be obtain by using the
active element pattern method multiplies with the array factor. The active element pattern is crucial as the
mutual coupling effect is considered, and it will lead to an accurate radiation pattern, especially in
determining direction of arrival (DoA) of a signal. A conventional method such as the pattern multiplication
method ignores the coupling effect which is essential especially for closely spaced antenna arrays. The
comparison between both techniques has been performed for better performance. It is observed that the
active element pattern influenced the radiation pattern of antenna arrays, especially at the side lobe level.
Then, the beam of the 3x3 dipole antenna array has been steered to an angle of 60° using three
techniques; Uniform, Chebyshev and Binomial distribution. All of these are accomplished using CST and
Matlab software
The presentation is about Adaptive Beamforming for high data-rate applications. Analog beamforming, which is considered a cost effective solution for consumer devices are investigated. Two adaptive analog beamforming algorithms, i.e., a well-known perturbation-based and dmr-based which overcomes the drawbacks of perturbation-based algorithm are discussed in-detail and their performance comparisons are made with the help of computer simulations. Also variation of single-port structure is considered and it's benefits are exploited with the help of modified analog beamforming algorithms.
non parametric methods for power spectrum estimatonBhavika Jethani
non-parametric methods for power spectrum estimation which includes bartlett method, welch method , blackman and tukey methods and also the comparision of all these methods
Performance Analysis of Ultra Wideband Receivers for High Data Rate Wireless ...graphhoc
For high data rate ultra wideband communication system, performance comparison of Rake, MMSE and Rake-MMSE receivers is attempted in this paper. Further a detail study on Rake-MMSE time domain equalizers is carried out taking into account all the important parameters such as the effect of the number of Rake fingers and equalizer taps on the error rate performance. This receiver combats inter-symbol interference by taking advantages of both the Rake and equalizer structure. The bit error rate performances are investigated using MATLAB simulation on IEEE 802.15.3a defined UWB channel models. Simulation results show that the bit error rate probability of Rake-MMSE receiver is much better than Rake receiver and MMSE equalizer. Study on non-line of sight indoor channel models illustrates that bit error rate performance of Rake-MMSE (both LE and DFE) improves for CM3 model with smaller spread compared to CM4 channel model. It is indicated that for a MMSE equalizer operating at low to medium SNR values, the number of Rake fingers is the dominant factor to improve system performance, while at high SNR values the number of equalizer taps plays a more significant role in reducing the error rate.
Performance Analysis of PAPR Reduction in MIMO-OFDMIJARBEST JOURNAL
Authors: Jayaraman.G1, VeeraKumar K2, Selvakani.S3
Abstract— In communication system, it is aimed to provide highest possible
transmission rate at the lowest possible power and with the least possible noise. MIMOOFDM
has been chosen for high data rate communications and widely deployed in many
wireless communication standards. The major drawback in OFDM signal transmission is
high PAPR. In previous, use clipping technique to tackle this problem. In this paper, use
EM-GAMP algorithm to reduce PAPR in considerable amount.
Simulation of an adaptive digital beamformer using matlabIJARBEST JOURNAL
Beam forming is the process of combining the weighted signals received on an array of
sensors to improve the directionality. Adaptive beamforming is the ability of the beamformer to
receive the signal only from the desired direction and to reject all other signals from undesired
directions. The weight vector for the adaptive beamformer continuously changes based on some
adaptive algorithm. Therefore, adaptive digital beam formers can point the antenna to the signal
direction without changing the physical architecture of the array antenna. The beam pointing
direction can be varied electronically with this technique. This paper focuses on Least Mean
Square (LMS) adaptive algorithm.
International Journal of Engineering and Science Invention (IJESI)inventionjournals
International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online.
In Digital Communications, a Turbo Equalizer is a type of receiver used to receive a message corrupted by a communication channel with intersymbol interference (ISI).
Elements Space and Amplitude Perturbation Using Genetic Algorithm for Antenna...CSCJournals
A simple and fast genetic algorithm (GA) developed to reduce the sidelobes in non-uniformly spaced linear antenna arrays. The proposed GA algorithm optimizes two vectors of variables to increase the Main lobe to Sidelobe power ratio (M/S) of array’s radiation pattern. The algorithm, in the first phase calculates the positions of the array elements and in the second phase, it manipulates the amplitude of excitation signals for each element. The simulations performed for 16 and 24 elements array structure. The results indicated that M/S improved in first phase from 13.2 to over 22.2dB meanwhile the half power beamwidth (HPBW) left almost unchanged. After element replacement, in the second phase, by using amplitude tapering further improvement up to 32dB was achieved. Also, the simulations shown that after element space perturbation, some antenna elements can be merged together without any performance degradation in radiation pattern in terms of gain and sidelobes level.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Computationally Efficient Multi-Antenna Techniques for Multi-User Two-Way Wire...IJECEIAES
In this work, we are interested in implementing, developing and evaluating multi-antenna techniques used for multi-user two-way wireless relay networks that provide a good tradeoff between the computational complexity and performance in terms of symbol error rate and achievable data rate. In particular, a variety of newly multi-antenna techniques is proposed and studied. Some techniques based on orthogonal projection enjoy low computational complexity. However, the performance penalty associated with them is high. Other techniques based on maximum likelihood strategy enjoy high performance, however, they suffer from very high computational complexity. The Other techniques based on randomization strategy provide a good trade-off between the computational complexity and performance where they enjoy low computational complexity with almost the same performance as compared to the techniques based on maximum likelihood strategy.
Survey paper on adaptive beamforming lms,nlms and rls algorithms for smart an...eSAT Journals
Abstract
Smart antenna system is used to maximize the output power of signal in desired direction and minimize the power in unwanted direction. Smart antenna system consists of multiple numbers of elements. Basic concept in smart antenna technology is beam forming, it is mainly used to improve signal to noise ratio. Beam forming signal processing technique used in sensor arrays for directional signal transmission and reception. And it possible by combining the elements in phased array in such a way that signals at particular angles experiences constructive interference and others are destructive interferences. In smart antenna system we are using various algorithms to calculate the weights of smart antenna arrays to increase the output in desired direction and reduce the power in unwanted direction We are using different types of arrays i.e. linear array, circular array, planar array . Different algorithms are used to adjust the weights of the smart antenna system Basically Weights are nothing but Amplitude and phase of the signal. Adaptive algorithms update the weights of the array elements. LMS algorithm provides less convergence speed, and that is depends on the step size. LMS algorithm is widely used in adaptive filter due to its relative low computational complexity, good stability and relatively good robustness against the implementation errors. To improve the convergence rate NLMS algorithm is used. LMS algorithm having constant step size but in NLMS algorithm step size is depends on data at each iteration. Whereas RLS algorithm having minimum bit error rate but it required more computations than the LSM algorithm.
Keywords: Beamforming, smart antenna, complex weight, array geometry, Array factor
Implementation of Digital Beamforming Technique for Linear Antenna Arraysijsrd.com
A digital Beamforming technique used for increased channel capacity and also increased signal to noise and interference ratio. In smart antenna, different type of radiation pattern of an antenna can be changed either by selecting appropriate weights or by changing the array geometry. This paper presented based on auxiliary phase algorithm by using this algorithm in linear antenna array determine the array pattern approximating the auxiliary function in both amplitude and phase. Cost function involving auxiliary function and array pattern is minimized by modifying the pattern.
A Wireless Sensor Network (WSN) is an autonomous and self-organizing network without any pre-established
infrastructure which offers many advantages in military applications and emergency areas. Source Localization is one of the important monitoring tasks of the WSN. It provides the accurate position of the source using various positioning technologies. In this paper an Impulse Radio Ultra wideband (IR-UWB) positioning system with a two-antenna receiver is used to estimate the Time of arrival (TOA) and Direction of arrival (DOA) positioning parameters. A two dimensional (2D) multiple signal classification (MUSIC) algorithm is used to estimate these parameters but it has much higher computational
complexity and also requires 2D spectral peak search. A Successive Multiple signal classification (MUSIC) algorithm is proposed in this paper which estimates the parameters jointly and gets paired automatically. It avoids the two dimensional peak searches and reduces the complexity compared to the existing methods 2D-MUSIC, Root-MUSIC, Matrix Pencil algorithm, Propagator method and Estimation of Signal Parameters via Rotational Invariance Techniques (ESPRIT) algorithm.
Keywords--Time of arrival (TOA), Direction of arrival (DOA), Impulse Radio Ultra Wideband (IR-UWB), Multiple
Signal Classification (MUSIC).
Performance analysis of adaptive beamforming at receiver side by using lms an...Ijrdt Journal
The Least Mean Squares (LMS) algorithm is an important member of the family of stochastic gradient algorithms. A significant feature of the LMS algorithm is its simplicity. The recursive least squares (RLS) algorithm recursively finds the filter coefficients for minimizing linear least squares cost function. Smart antenna generally refers to any antenna array. Beamforming is a signal processing technique used in sensor arrays for directional signal transmission or reception. This spatial selectivity is achieved by using adaptive or fixed receive/transmit beam patterns. The improvement compared with an omnidirectional reception/transmission is known as the receive/transmit gain (or loss). In this study, fixed weight beamforming basics and maximum signal to interference ratio are given. The theoretical information of adaptive beamforming, LMS (Least Mean Square) and RLS (Recursive Mean Squares) algorithms are explained. Adaptive beamforming in recieve antenna is simulated by using LMS and RLS algorithms. Simulation results are discussed and explained.
Three Element Beam forming Algorithm with Reduced Interference Effect in Sign...IJMER
International Journal of Modern Engineering Research (IJMER) is Peer reviewed, online Journal. It serves as an international archival forum of scholarly research related to engineering and science education.
Green Roofs and Green Building Rating SystemsIJERA Editor
The environmental benefits for green building from the Leadership in Energy and Environment Design (LEED)
and Ecology, Energy, Waste, and Health (EEWH) rating systems have been extensively investigated; however,
the effect of green roofs on the credit-earning mechanisms is relatively unexplored. This study is concerned with
the environmental benefits of green roofs with respect to sustainability, stormwater control, energy savings, and
water resources. We focused on the relationship between green coverage and the credits of the rating systems,
evaluated the credits efficiency, and performed cost analysis. As an example, we used a university building in
Keelung, Northern Taiwan. The findings suggest that with EEWH, the proposed green coverage is 50–75%,
whereas with LEED, the proposed green coverage is 100%. These findings have implications for the application
of green roofs in green building.
Unsteady Free Convection MHD Flow of an Incompressible Electrically Conductin...IJERA Editor
In this paper we investigate unsteady free convection MHD flow of an incompressible viscous electrically
conducting fluid through porous medium under the influence of uniform transverse magnetic field between two
heated vertical plate with one plate is adiabatic. The governing equations of velocity and temperature fields with
appropriate boundary conditions are solved by the Integral Transform Technique. The obtained results of
velocity and temperature distributions are shown graphically and are discussed on the basis of it. The effects of
Hartmann number, Darcy parameter, Prandtl number and the decay factor, and effects of adiabatic plate on the
velocity and temperature fields are discussed.
Simulation of an adaptive digital beamformer using matlabIJARBEST JOURNAL
Beam forming is the process of combining the weighted signals received on an array of
sensors to improve the directionality. Adaptive beamforming is the ability of the beamformer to
receive the signal only from the desired direction and to reject all other signals from undesired
directions. The weight vector for the adaptive beamformer continuously changes based on some
adaptive algorithm. Therefore, adaptive digital beam formers can point the antenna to the signal
direction without changing the physical architecture of the array antenna. The beam pointing
direction can be varied electronically with this technique. This paper focuses on Least Mean
Square (LMS) adaptive algorithm.
International Journal of Engineering and Science Invention (IJESI)inventionjournals
International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online.
In Digital Communications, a Turbo Equalizer is a type of receiver used to receive a message corrupted by a communication channel with intersymbol interference (ISI).
Elements Space and Amplitude Perturbation Using Genetic Algorithm for Antenna...CSCJournals
A simple and fast genetic algorithm (GA) developed to reduce the sidelobes in non-uniformly spaced linear antenna arrays. The proposed GA algorithm optimizes two vectors of variables to increase the Main lobe to Sidelobe power ratio (M/S) of array’s radiation pattern. The algorithm, in the first phase calculates the positions of the array elements and in the second phase, it manipulates the amplitude of excitation signals for each element. The simulations performed for 16 and 24 elements array structure. The results indicated that M/S improved in first phase from 13.2 to over 22.2dB meanwhile the half power beamwidth (HPBW) left almost unchanged. After element replacement, in the second phase, by using amplitude tapering further improvement up to 32dB was achieved. Also, the simulations shown that after element space perturbation, some antenna elements can be merged together without any performance degradation in radiation pattern in terms of gain and sidelobes level.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Computationally Efficient Multi-Antenna Techniques for Multi-User Two-Way Wire...IJECEIAES
In this work, we are interested in implementing, developing and evaluating multi-antenna techniques used for multi-user two-way wireless relay networks that provide a good tradeoff between the computational complexity and performance in terms of symbol error rate and achievable data rate. In particular, a variety of newly multi-antenna techniques is proposed and studied. Some techniques based on orthogonal projection enjoy low computational complexity. However, the performance penalty associated with them is high. Other techniques based on maximum likelihood strategy enjoy high performance, however, they suffer from very high computational complexity. The Other techniques based on randomization strategy provide a good trade-off between the computational complexity and performance where they enjoy low computational complexity with almost the same performance as compared to the techniques based on maximum likelihood strategy.
Survey paper on adaptive beamforming lms,nlms and rls algorithms for smart an...eSAT Journals
Abstract
Smart antenna system is used to maximize the output power of signal in desired direction and minimize the power in unwanted direction. Smart antenna system consists of multiple numbers of elements. Basic concept in smart antenna technology is beam forming, it is mainly used to improve signal to noise ratio. Beam forming signal processing technique used in sensor arrays for directional signal transmission and reception. And it possible by combining the elements in phased array in such a way that signals at particular angles experiences constructive interference and others are destructive interferences. In smart antenna system we are using various algorithms to calculate the weights of smart antenna arrays to increase the output in desired direction and reduce the power in unwanted direction We are using different types of arrays i.e. linear array, circular array, planar array . Different algorithms are used to adjust the weights of the smart antenna system Basically Weights are nothing but Amplitude and phase of the signal. Adaptive algorithms update the weights of the array elements. LMS algorithm provides less convergence speed, and that is depends on the step size. LMS algorithm is widely used in adaptive filter due to its relative low computational complexity, good stability and relatively good robustness against the implementation errors. To improve the convergence rate NLMS algorithm is used. LMS algorithm having constant step size but in NLMS algorithm step size is depends on data at each iteration. Whereas RLS algorithm having minimum bit error rate but it required more computations than the LSM algorithm.
Keywords: Beamforming, smart antenna, complex weight, array geometry, Array factor
Implementation of Digital Beamforming Technique for Linear Antenna Arraysijsrd.com
A digital Beamforming technique used for increased channel capacity and also increased signal to noise and interference ratio. In smart antenna, different type of radiation pattern of an antenna can be changed either by selecting appropriate weights or by changing the array geometry. This paper presented based on auxiliary phase algorithm by using this algorithm in linear antenna array determine the array pattern approximating the auxiliary function in both amplitude and phase. Cost function involving auxiliary function and array pattern is minimized by modifying the pattern.
A Wireless Sensor Network (WSN) is an autonomous and self-organizing network without any pre-established
infrastructure which offers many advantages in military applications and emergency areas. Source Localization is one of the important monitoring tasks of the WSN. It provides the accurate position of the source using various positioning technologies. In this paper an Impulse Radio Ultra wideband (IR-UWB) positioning system with a two-antenna receiver is used to estimate the Time of arrival (TOA) and Direction of arrival (DOA) positioning parameters. A two dimensional (2D) multiple signal classification (MUSIC) algorithm is used to estimate these parameters but it has much higher computational
complexity and also requires 2D spectral peak search. A Successive Multiple signal classification (MUSIC) algorithm is proposed in this paper which estimates the parameters jointly and gets paired automatically. It avoids the two dimensional peak searches and reduces the complexity compared to the existing methods 2D-MUSIC, Root-MUSIC, Matrix Pencil algorithm, Propagator method and Estimation of Signal Parameters via Rotational Invariance Techniques (ESPRIT) algorithm.
Keywords--Time of arrival (TOA), Direction of arrival (DOA), Impulse Radio Ultra Wideband (IR-UWB), Multiple
Signal Classification (MUSIC).
Performance analysis of adaptive beamforming at receiver side by using lms an...Ijrdt Journal
The Least Mean Squares (LMS) algorithm is an important member of the family of stochastic gradient algorithms. A significant feature of the LMS algorithm is its simplicity. The recursive least squares (RLS) algorithm recursively finds the filter coefficients for minimizing linear least squares cost function. Smart antenna generally refers to any antenna array. Beamforming is a signal processing technique used in sensor arrays for directional signal transmission or reception. This spatial selectivity is achieved by using adaptive or fixed receive/transmit beam patterns. The improvement compared with an omnidirectional reception/transmission is known as the receive/transmit gain (or loss). In this study, fixed weight beamforming basics and maximum signal to interference ratio are given. The theoretical information of adaptive beamforming, LMS (Least Mean Square) and RLS (Recursive Mean Squares) algorithms are explained. Adaptive beamforming in recieve antenna is simulated by using LMS and RLS algorithms. Simulation results are discussed and explained.
Three Element Beam forming Algorithm with Reduced Interference Effect in Sign...IJMER
International Journal of Modern Engineering Research (IJMER) is Peer reviewed, online Journal. It serves as an international archival forum of scholarly research related to engineering and science education.
Green Roofs and Green Building Rating SystemsIJERA Editor
The environmental benefits for green building from the Leadership in Energy and Environment Design (LEED)
and Ecology, Energy, Waste, and Health (EEWH) rating systems have been extensively investigated; however,
the effect of green roofs on the credit-earning mechanisms is relatively unexplored. This study is concerned with
the environmental benefits of green roofs with respect to sustainability, stormwater control, energy savings, and
water resources. We focused on the relationship between green coverage and the credits of the rating systems,
evaluated the credits efficiency, and performed cost analysis. As an example, we used a university building in
Keelung, Northern Taiwan. The findings suggest that with EEWH, the proposed green coverage is 50–75%,
whereas with LEED, the proposed green coverage is 100%. These findings have implications for the application
of green roofs in green building.
Unsteady Free Convection MHD Flow of an Incompressible Electrically Conductin...IJERA Editor
In this paper we investigate unsteady free convection MHD flow of an incompressible viscous electrically
conducting fluid through porous medium under the influence of uniform transverse magnetic field between two
heated vertical plate with one plate is adiabatic. The governing equations of velocity and temperature fields with
appropriate boundary conditions are solved by the Integral Transform Technique. The obtained results of
velocity and temperature distributions are shown graphically and are discussed on the basis of it. The effects of
Hartmann number, Darcy parameter, Prandtl number and the decay factor, and effects of adiabatic plate on the
velocity and temperature fields are discussed.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Scenario of Rural Electrification in India- Challenges and ImpactIJERA Editor
In this paper, the present scenario of rural electrification in India is taken into account. Basically, the electrification in this country is facing a lot of problem and is a growing matter of concern for all. The development in production is not reaching the one who need them. Also taking into picture the present sources of energy it is difficult to make the electricity available to the people belonging to rural areas who don’t have much source of income. To overcome this drawback we can utilise renewable sources of energy which is easily available and accessible. Also harvesting this will not cost much except the initial cost of setting up the device to utilise this type of energy. Many projects have been initiated by the government of India to provide subsidy and equipments like solar lantern and solar cooker etc. to the rural population but this didn’t turn out to be effective as the follow could not be done by the people to maintain the devices. This can be overcome by implementing off-grid projects which can be initiated at small levels so that people don’t have burden to maintain them and it even don’t have any adverse effect to environment or society.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Deterministic Assessment of Continuous Flight Auger Construction Durations Us...IJERA Editor
One of the primary functions of construction equipment management is to calculate the production rate of equipment which will be a major input to the processes of time estimates, cost estimates and the overall project planning. Accordingly, it is crucial to stakeholders to be able to compute equipment production rates. This may be achieved using an accurate, reliable and easy tool. The objective of this research is to provide a simple model that can be used by specialists to predict the duration of a proposed Continuous Flight Auger job. The model was obtained using a prioritizing technique based on expert judgment then using multi-regression analysis based on a representative sample. The model was then validated on a selected sample of projects. The average error of the model was calculated to be about (3%-6%).
Dimensional and Constructional Details of Components, Fundamentals of TNM Met...IJERA Editor
For the improvement in thermal design of squirrel cage induction (SCIM) motor, it is essential to know details
of the methods for evaluation of thermal distribution in a SCIM motor. A presentation of various details of
methods of basics of heat transfer that occur in a SCIM motor is done in this report. SCIM motors have wide
applications and thus their construction is completely influenced by the starting characteristics specified by the
operating loads. General constraints of a motor and specification of 30 KW motor are presented in this report as
a case study of constraints. As the next step the Thermal Network Method (TNM) has been explained.
Physico-Chemical Analysis of Underground Water from Silchar Municipal Area of...IJERA Editor
Water samples were collected from different sources of Silchar Municipal area of Cachar district, Assam, India.
Physicochemical parameter such as PH
, EC, Hardness, Chloride, Fluorides, Iron, TDS of sixteen water samples
from different sampling sites of Silchar were determined. The experimental results were compared with
drinking water quality standards laid down by Indian Council of Medical Research (ICMR) and World Health
Organization (WHO) and it was found that only a few water samples are not suitable for drinking and other
domestic purposes due to high concentration of iron. Overall all the ground water is clear, odourless and soft.
Even few samples contain fluoride ion but the values are much below the permissible limits.
Research onidentify stadia of interchange exit ramp in mountainous urban freewayIJERA Editor
Theidentify stadia of interchange exit ramp hasgreat influence on capacity and safety levels of urbanexpressway,combining with car psychological theory and driverscharacteristics,based on design speed and driver's reaction time, driversoperating characteristics and the cause of the accident on interchange exit ramp was analyzed and the identify stadia threshold under different design speedwas determined. The resultindicates that: the requirements of specification for identify stadia has some limitations, it should be modified appropriately.
Using Data Mining Techniques in Customer SegmentationIJERA Editor
Data mining plays important role in marketing and is quite new. Although this field expands rapidly, data mining is still foreign issue for many marketers who trust only their experiences. Data mining techniques cannot substitute the significant role of domain experts and their business knowledge. In the other words, data mining algorithms are powerful but cannot effectively work without the active support of business experts. We can gain useful results by combining these techniques and business expertise. For instance ability of a data mining technique can be substantially increased by combining person experience in the field or information of business can be integrated into a data mining model to build a more successful result. Moreover, these results should always be evaluated by business experts. Thus, business knowledge can help and enrich the data mining results. On the other hand, data mining techniques can extract patterns that even the most experienced business people may have missed. In conclusion, the combination of business domain expertise with the power of data mining techniques can help organizations gain a competitive advantage in their efforts to optimize customer management. Clustering algorithms, a group of data mining technique, is one of most common used way to segment data set according to their similarities. This paper focuses on the topic of customer segmentation using data mining techniques. In the other words, we theoretically discuss about customer relationship management and then utilize couple of data mining algorithm specially clustering techniques for customer segmentation. We concentrated on behavioral segmentation.
Radix-2 Algorithms for realization of Type-II Discrete Sine Transform and Typ...IJERA Editor
In this paper, radix-2 algorithms for computation of type-II discrete sine transform (DST-II) and type-IV
discrete sine transform (DST-IV), each of length 2 ( 2,3,.....)
m
N m , are presented. The odd-indexed
output components of DST-II can be realized using simple recursive relations. The recursive algorithms are
appropriate for VLSI implementation. The DST-IV of length N can be computed from type-II discrete cosine
transform (DCT-II) and DST-II sequences, each of length N/2.
Effect of Nozzle Design and Processing Parameter on Characteristics of Glass/...IJERA Editor
Among the various methods commingling process is comparatively better alternative to produce hybrid yarns. The required properties of hybrid yarns can be obtained by controlling main processing parameters such as air pressure, overfeed and take-up speed along with proper selection of nozzle (jet) design. The commingling machine has been fabricated to study the commingling parameters. The nozzle is the most important element of the commingling machine. The design specification of commingling jet along with the processing parameters decides the final characteristics of yarn. In the present study two different types of jets have been selected to investigate commingling characteristics of glass/polypropylene hybrid yarn.
Voice Activity Detector of Wake-Up-Word Speech Recognition System Design on FPGAIJERA Editor
A typical speech recognition system is push-to-talk operated that requires activation. However for those who use hands-busy applications, movement may by restricted or impossible. One alternative is to use Speech-Only Interface. The proposed method that is called Wake-Up-Word Speech Recognition (WUW-SR) that utilizes speech only interface. A WUW-SR system would allow the user to activate systems (Cell phone, Computer, etc.) with only speech commands instead of manual activation. The trend in WUW-SR hardware design is towards implementing a complete system on a single chip intended for various applications. This paper presents an experimental FPGA design and implementation of a novel architecture of a real time feature extraction processor that includes: Voice Activity Detector (VAD), and features extraction, MFCC, LPC, and ENH_MFCC. In the WUW-SR system, the recognizer front-end with VAD is located at the terminal which is typically connected over a data network(e.g., server)for remote back-end recognition. VAD is responsible for segmenting the signal into speech-like and non-speech-like segments. For any given frame VAD reports one of two possible states: VAD_ON or VAD_OFF. The back-end is then responsible to score the features that are being segmented during VAD_ON stage. The most important characteristic of the presented design is that it should guarantee virtually 100% correct rejection for non-WUW (out of vocabulary words - OOV) while maintaining correct acceptance rate of 99.9% or higher (in vocabulary words - INV). This requirement sets apart WUW-SR from other speech recognition tasks because no existing system can guarantee 100% reliability by any measure.
Spectroscopic studies on Mn2+ ions doped Cadmium Aluminum Fluoro Lead Borate ...IJERA Editor
This article reports on optical properties of Mn2+ (0.5 mol%): 49.5 B2O3 - 10PbO - 30CdO -10AlF3 glasses.
Optical absorption spectrum of the manganese ions doped glass exhibits broad absorption band at 473 nm.
Photoluminescence spectrum of Mn2+ (0.5 mol %): 49.5B2O3- 30CdO – 10PbO - 10AlF3 glass has revealed a red
emission at 618 nm with an excitation wavelength 467 nm.
Burning Behavior of Liquid Fuel DropletsIJERA Editor
Ignition of flammable liquids by hot surfaces is well known to automotive and aviation industries. However, only a limited data regarding hot surface ignition (HSI) of pure and commercial fuels is available in literature. Further, relatively few studies have determined the ignition delay and to our knowledge the combustion lifetime. In the present work, we have generated results from an efficient, reproducible, yet simple experimental setup involving a liquid fuel droplet, a horizontal heated stainless steel plate and quiescent environment. Tests were conducted for diesel, biodiesel and its blends as well as vegetable oils, applied/used as single droplets under variety of conditions to the heated surface. The droplet size range was approximately between 1500 micron to 2000 micron. The objective of this experiment was to determine the minimum temperatures for HSI and also the temperatures where 100% probability of ignition was expected. Further, from this experiment, we were also able to obtain the ignition delay and droplet lifetime. As an extension to this study, a separate droplet combustion model was developed to closely study the general burning behavior of these droplets by generating temperature and species concentration profiles. The droplet mass burning rate was also determined. The results obtained in the present work were in a general agreement with the experimental and modeling observations of other studies.
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this review paper presents closed loop control techniques for controlling the inverter working under different load or KVA ratings. The control strategy of the inverter must guarantee its output waveforms to be sinusoidal with fundamental harmonic. For this purpose, close loop current control strategies such as H∞ repetitive controller, dual closed-loop feedback control, Adaptive Voltage Control, SRFPI controller, Optimal Neural Controller, etc. have been used to meet the power quality requirements imposed by IEEE Interconnection Standards. Based on present scenario regarding energy crises, immediate action is the use of different renewable energy sources (RESs) . Out of RESs, solar is gaining more attention. It is very important to design and developed a system which should be efficient enough to utilize the extracted energy for different types of load and feeding of energy into utility grid. Since experimentation and comparison of such inverter models on hardware being relatively expensive, the latest computing tool like MATLAB are considered to be a better alternative to simulate the outcomes of such expensive systems. The proposed closed loop control technique for the inverter working under linear and nonlinear system will be implemented in MATLAB/SIMULINK working platform and results will be analyzed to check its benefits.
International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online.
Direction of Arrival Estimation Based on MUSIC Algorithm Using Uniform and No...IJERA Editor
In signal processing, the direction of arrival (DOA) estimation denotes the direction from which a propagating wave arrives at a point, where a set of antennas is located. Using the array antenna has an advantage over the single antenna in achieving an improved performance by applying Multiple Signal Classification (MUSIC) algorithm. This paper focuses on estimating the DOA using uniform linear array (ULA) and non-uniform linear array (NLA)of antennas to analyze the performance factors that affect the accuracy and resolution of the system based on MUSIC algorithm. The direction of arrival estimation is simulated on a MATLAB platform with a set of input parameters such as array elements, signal to noise ratio, number of snapshots and number of signal sources. An extensive simulation has been conducted and the results show that the NLA with DOA estimation for co-prime array can achieve an accurate and efficient DOA estimation
High Resolution Method using Patch Circular Array IJECEIAES
Smart antennas have recently received increasing for improving the performance of wireless radio systems. In this research article, we have used a patch antenna using uniform circular arrays (UCA) with central element for direction of arrival (DOA). A central element was added to arrays in order to increase steering capability of the proposed array. This geometry is used to determine the elevation and azimuth based on two famous algorithms of high resolution method: Matrix Pencil method (MP) and MUltiple Signal Classification (MUSIC).The comparison results demonstrate clearly that the matrix pencil is more accurate and stable to estimation of direction of arrival compared to the MUSIC algorithm.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Smart Antenna is a device with signal processing
capability combining multiple antenna elements to optimize its
radiation and reception patterns as per designed specifications.
Smart antennas basically comprise of two functionalities, i.e.,
Direction of Arrival and Beamforming. This paper explains the
estimation of Direction of Arrival using MLM method and a
novel approach called MUltiple Signal Classification which takes
advantage of orthogonal property and performs subspace
computation. With a comparative study of both the algorithms,
we shall prove the advantages of MUltiple Signal Classification
over the MLM method with the aid of MATLAB
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Adaptive array smart antenna involves the array
processing to manipulate the signals induced on various antenna elements in such way that the main beam directing towards the desired signal and forming the nulls towards the interferers. Such smart antennas are widely used in wireless mobile communications as they can increase the channel capacity and coverage range. In adaptive array smart antenna, to locate the
desired signal, various direction of arrival (DOA) estimation algorithms are used. This paper investigates Novel Snapshot Based approach using Estimation of Signal Parameters via Rotational Invariance Technique. ESPRIT algorithms provide high angular resolution and hence they are explored much in detail by varying various parameters of smart antenna system.
Index Terms—Smart antenna, ESPIRT, DOA, AOA
Author: S.M.Shashidhara
Design of Linear Array Transducer Using Ultrasound Simulation Program Field-IIinventy
This paper analyze the effect of number of elements of linear array and frequency influence the
image quality in a homogenous medium. Linear arrays are most common for conventional ultrasound imaging,
because of the advantages of electronic focusing and steering. Propagation of ultrasound in biological tissues is
of nonlinear in nature. But linear approximation in far-field is promising solution to model and simulate the
real time ultrasound wave propagation. The simulation of ultrasound imaging using linear acoustics has been
most widely used for understanding focusing, image formation and flow estimation, and it has become a
standard tool in ultrasound research. . In this paper the ultrasound field generated from linear array transducer
and propagation through biological tissues is modeled and simulated using FIELD II program.
performance analysis of MUSIC and ESPRIT DOA estimation used in adaptive arra...CSCJournals
MUSIC and ESPRIT DOA Estimaion algorithms are widely used in adaptive array to locate the desired desired signal.MUSIC is found to be more stable and accurate and widely used inthe design of adaptive array.
This paper presented a compressive sensing (CS) calibration technique that simultaneously measures all the element excitations of a 2×2 active phased antenna array (APAA) instantaneously. The power patterns of the rectangular 2×2 APAA element are synchronized to orthogonally cross multiplicative sub-array system applying compressive sensing in achieving an array thinning along two 1-D sub-arrays for a fixed steered beam radiation. The far field radiation pattern direction of the 2×2 APAA is examined considering the mutual effect, complex excitation of the amplitude and phase of the antenna elements placed on the x and y axes. The unwanted array excitation with errors are calibrated using minimization vector as a standard basic pursuit problem in compressive sensing technique for the 2×2 APAA calibration. The elements amplitude and phase shift variation are compared with reference state 0 in order to evaluate the faulty error array elements. The performance evaluation of this proposed technique is measured and demonstrated to validate the effectiveness of the proposed antenna calibration technique.
Comparative analysis on an exponential form of pulse with an integer and non-...IJERA Editor
The theme of this paper is to make a fundamental comparative analysis on time-bandwidth product of a short
duration pulse, whose amplitude is varied with an exponent as an integer and non-integer. The time-bandwidth
product is the most significant factor in pulse compression techniques which is used very often in radar systems
for better detection of the target and resolving the ambiguities in the both range and velocity with the help of
ambiguity function. In this paper, different exponents have been used and it is observed that the non-integer
exponents are giving slightly better quantitative parameters like time-bandwidth product, relative sidelobe level
and main lobe widths. To improve these quantitative parameters, phase variations have been incorporated with
the differentiated pulses of the original exponential signal. Finally, the modulation has also been applied on the
pulses to observe the results in real practical applications. From all these analysis, it is concluded that the
differentiated non-integer exponential pulse with bi-polar variations is giving better pulse compression
requirements (time-bandwidth product, peak sidelobe level, 3-dB beamwidth and main lobe widths) compared
to all other pulse forms. The outputs of the matched filter are also observed for each pulse shape.
Comparitive analysis of doa and beamforming algorithms for smart antenna systemseSAT Journals
Abstract This paper revolves around the implementation of Direction of arrival and Adaptive beam-forming algorithms for Smart Antenna Systems. This paper also investigates the implementation of algorithms on various planner array geometries viz. circular and rectangular. Music algorithm is primarily finds the possible location of desired user and adaptive beam-forming algorithms such as LMS, RLS and CMA algorithms adapts the weights of the array. DOA estimation gives the maximum peak of spectrum with respect to angle of arrival where the desired user is supposed to exist. After DOA estimation weights of array antenna are changed with the changing received signal. This methodology is called as Spectral estimation, which allows the antenna pattern to steer in desired direction estimated by DOA and simultaneously null out the interfering signals. Rate of convergence is the major criterion for comparison for adaptive beam-forming algorithms. Keywords: DOA, MUSIC, LMS, RLS, CMA, SAS.
Key Trends Shaping the Future of Infrastructure.pdfCheryl Hung
Keynote at DIGIT West Expo, Glasgow on 29 May 2024.
Cheryl Hung, ochery.com
Sr Director, Infrastructure Ecosystem, Arm.
The key trends across hardware, cloud and open-source; exploring how these areas are likely to mature and develop over the short and long-term, and then considering how organisations can position themselves to adapt and thrive.
Epistemic Interaction - tuning interfaces to provide information for AI supportAlan Dix
Paper presented at SYNERGY workshop at AVI 2024, Genoa, Italy. 3rd June 2024
https://alandix.com/academic/papers/synergy2024-epistemic/
As machine learning integrates deeper into human-computer interactions, the concept of epistemic interaction emerges, aiming to refine these interactions to enhance system adaptability. This approach encourages minor, intentional adjustments in user behaviour to enrich the data available for system learning. This paper introduces epistemic interaction within the context of human-system communication, illustrating how deliberate interaction design can improve system understanding and adaptation. Through concrete examples, we demonstrate the potential of epistemic interaction to significantly advance human-computer interaction by leveraging intuitive human communication strategies to inform system design and functionality, offering a novel pathway for enriching user-system engagements.
Essentials of Automations: Optimizing FME Workflows with ParametersSafe Software
Are you looking to streamline your workflows and boost your projects’ efficiency? Do you find yourself searching for ways to add flexibility and control over your FME workflows? If so, you’re in the right place.
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The Art of the Pitch: WordPress Relationships and SalesLaura Byrne
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The publishing industry has been selling digital audiobooks and ebooks for over a decade and has found its groove. What’s changed? What has stayed the same? Where do we go from here? Join a group of leading sales peers from across the industry for a conversation about the lessons learned since the popularization of digital books, best practices, digital book supply chain management, and more.
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Length: 30 minutes
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FIDO Alliance Osaka Seminar: Passkeys and the Road Ahead.pdf
Ag4301181184
1. G. Balagurappa et al Int. Journal of Engineering Research and Applications www.ijera.com
ISSN : 2248-9622, Vol. 4, Issue 3( Version 1), March 2014, pp.181-184
www.ijera.com 181 | P a g e
Low Cost Em Signal Spectral Analysis with Two Element Time
Modulated Array System by Multiple Signal Classification
Algorithms
G. Balagurappa, J. Sreenivasa Reddy
M.Tech Academic assistant Deparment of ECE, JNTUA CE ,Pulivendula
M.Tech Assistant professor K.S.R.M Engg college,KADAPA
ABSTRACT
Today homeland security is a big matter of concern. The present day wireless technology is available to anti-
social elements, who are using this in several undesirable manners. By knowing the direction of the source of
electromagnetic waves it becomes possible to locate such anti-social groups and take offensive action. In
military applications also finding the direction of the signal source becomes very valuable information. The
direction finding systems can achieve this goal.
Conventional radio direction finding (RDF) systems often use an array of two or more antennas and use either
phase-comparison or amplitude-comparison of the received signals to determine direction of arrival information.
In both of these techniques directional information is derived by processing array data at the receive signal
frequency.
In this project an alternative approach to direction finding using the concept of a time-switched array is
proposed. The time-switched array system uses simple signal processing techniques to provide a directional
main beam and pattern nulls at harmonic frequencies. To determine two dimensional angles is three elements,
the system cost has been mostly minimised. we now consider the problem of using our low cost system to detect
and estimate the direction of arrival of a desired signal in the presence of array antenna.
The proposed scheme is cost effective technique in comparison with the existing schemes.
MATLAB/GNU OCTAVE simulation tool will be used for simulation. The simulation results, applications,
merits and demerits of proposed approach will be analyzed and will be documented.
Index Terms-antenna, array, direction finding.
I. INTRODUCTION
Conventional Radio Direction Finding
(RDF) systems often use an array of two or more
antennas and also by using the concept of a time-
switched array. The time-switched array systems uses
simple signal processing techniques to provide a
directional main beam and pattern nulls at harmonic
frequencies use either phase-comparison of
amplitude-comparison of the received signal to
determine direction of arrival information. In both of
these techniques directional information is derived by
processing array data at the receive signal frequency.
It has been exploited in numerous applications (e.g.,
radar, sonar, wireless communications, seismic
exploration, speech processing, medical imaging,
radio astronomy).
Fig 1: Two Element Time-Switched Array and
definition of switching wave forms.
Time-modulated arrays we first proposed as
a means of producing low side lobe antenna patterns
by using simple on-off switching of the array
element. The technique allows conventional array
amplitude weighting patterns to be synthesized in a
time-average sense by switching the array element on
RESEARCH ARTICLE OPEN ACCESS
2. G. Balagurappa et al Int. Journal of Engineering Research and Applications www.ijera.com
ISSN : 2248-9622, Vol. 4, Issue 3( Version 1), March 2014, pp.181-184
www.ijera.com 182 | P a g e
for a period that corresponds to the relative amplitude
weight of the array element.
An inherent problem normally associated
with time-modulated arrays is that they generate
unwanted harmonics, or sidebands, at multiples of the
switching frequency and most research into time-
modulated arrays has concentrated on minimizing or
controlling these harmonics [4]-[9]. More recently
work has been carried out to investigate the use of
phase centre motion to control side lobe levels [10]
and the application of time-modulated arrays in
Doppler radar.
In this contribution we describe a prototype
two element time-switched array system and present
measured data to illustrate the performance of the
array.
Direction of arrival
We have seen that there is a one-to-one
relationship between the direction of a signal and the
associated received steering vector. It should
therefore be possible to invert the relationship and
estimate the direction of a signal from the received
signals. An antenna array therefore should be able to
provide for direction of arrival estimation. We have
also seen that there is a Fourier relationship between
the beam pattern and the excitation at the array. This
allows the direction of arrival (DOA) estimation
problem to be treated as equivalent to spectral
estimation.
Fig 2: The DOA estimation problem
The problem set up is shown in Fig. 2.
Several (M) signals impinge on a linear, equispaced,
array with N elements, each with direction φi. The
goal of DOA estimation is to use the data received at
the array to estimate φi, i = 1, . . .M. It is generally
assumed that M < N, though there exist approaches
(such as maximum likelihood estimation) that do not
place this constraint.
II. SYSTEM DESCRIPTION
The time-switched array system is shown
schematically in Fig.1 and consists of two antenna
elements separated by a distance d. Each element is
assumed to exhibit an Omni directional radiation
pattern in the plane of the diagram. The output from
each element is connected to the array output via a
switch in the feed line; the element switching period
are also defined in Fg.1. A complete analysis of the
system may be found in [2] but for the purpose of this
contribution we will assume that the elements are
alternately switched on and off with an equal mark-
space ratio square wave switching function such that
= =
If we assume that the spacing between the
elements is a half wavelength, the output from the
array may be described [2] by
A (θ,t) = ,where
Fig 3: Details of the measurement set-up.
Hence the output of the array is phase
modulated and the depth of modulation is dependent
on the angle of arrival of the incident signal. For
illumination broadside to the array, the array output is
not modulated. However, as the illumination angle
increases the depth of modulation increases until at
end fire illumination (θ = 90deg and the array output
exhibits 270 deg phase shift modulation. A plot of the
array receive pattern at the illumination frequency,
, is given in Fig.2 and shows a directional
response with a peak on broadside and a null
response at The directional pattern occurs
because as the depth of phase modulation increases
energy is redistributed from the carrier into
sidebands, and at end fire there is zero energy at the
carrier frequency. If we now examine the output of
the time-switched array at the first harmonic.
Multiple Signal Classification Algorithms:
Of all techniques shown in Fig. 2, MUSIC is
probably the most popular technique. MUSIC, as are
many adaptive techniques, is dependent on the
correlation matrix of the data. Using the data model ,
3. G. Balagurappa et al Int. Journal of Engineering Research and Applications www.ijera.com
ISSN : 2248-9622, Vol. 4, Issue 3( Version 1), March 2014, pp.181-184
www.ijera.com 183 | P a g e
The matrix S is a N ×M matrix of the M
steering vectors. Assuming that the different signals
to be uncorrelated, the correlation matrix of x can be
written as
Where
The signal covariance matrix, Rs, is clearly
a N × N matrix with rank M. It therefore has N−M
eigenvectors corresponding to the zero eigenvalue.
Let qm be such an eigenvector. Therefore,
where this final equation is valid since the matrix A is
clearly positive definite. Equation (49) implies that
all N −M eigenvectors (qm) of Rs corresponding to
the zero eigenvalue are orthogonal. to all M signal
steering vectors. This is the basis for MUSIC. Call
Qn the N ×(N −M) matrix of these eigenvectors.
Note that since the eigenvectors making up
Qn are orthogonal to the signal steering vectors, the
denominator becomes zero when φ is a signal
direction.
Algorithm steps
Step1: Estimate the correlation matrix R using Eqn.
(54). Find its eigendecomposition R = QΛQH.
Step 2: Partition Q to obtain Qn, corresponding to the
(N − M) smallest eigenvalues of Q, which spans the
noise subspace.
Step 3: Plot, as a function of φ, the MUSIC function
PMUSIC (φ) in Eqn. (53).
Step 4: The M signal directions are the M largest
peaks of PMUSIC (φ).
The time-switched array was designed and
constructed to operate at 2400MHz using quarter-
wave monopoles as the two array elements. The
monopoles were constructed from 1.5 mm copper
wire mounted on a 200 mm diameter ground plane
using chassis mounting 3.5mm connectors. Because
the array was only required to operate with equal
mark-space ratio square-wave switching, a SPDT
switch was constructed based on a design provided
by Philips Semiconductors using BAP51-02 surface
mount PIN diodes. The switch was using constructed
using micro strip on standard FR4 circuit board. The
switch was mounted on the underside of the array
ground plane and connections were made to the
monopoles using connected to the monopoles using
short length of co-axial cable. However as the outputs
of the SPDT switch were not phase matched, a co-
axial line stretcher was inserted into one of the
monopole connections to allow phase compensation.
For ease of measurement the array was tested when
operating in transmit mode. The measurements were
made in an anechoic antenna test chamber using an
HP 8350B as the RF source and an Agilent E4407B
spectrum analyzer as a receiver.
Fig 4: Spectral Analysis using MUSIC Algorithm
0 50 100 150 200 250 300 350 400
-25
-20
-15
-10
-5
0
5
10
Output
Angle (deg)
Gain(dB)
Fig 5: Measured Angle of Arrival: 90,270
Antenna Arrays
An antenna Array is a configuration of
individual radiating elements that are arranged in
4. G. Balagurappa et al Int. Journal of Engineering Research and Applications www.ijera.com
ISSN : 2248-9622, Vol. 4, Issue 3( Version 1), March 2014, pp.181-184
www.ijera.com 184 | P a g e
space and can be used to produce a directional
radiation pattern Single-element antennas have
radiation patterns that are broad and hence have a low
directivity that is not suitable for long distance
communications.
A high directivity can be still be achieved by
increasing the electrical dimensions (in terms of
wavelength) and hence the physical size of the
antenna.
0.5
1
30
210
60
240
90
270
120
300
150
330
180 0
0.5
1
30
210
60
240
90
270
120
300
150
330
180 0
Fig 6: Array Factor and Array Element
The SPDT switch was modulated with a
square wave derived from a standard laboratory
signal generator at a frequency of 20 kHz. Fig. 3
shows the received spectrum measured broadside to
the array prior to phase compensation.
The spectrum contains a components at the
fundamental frequency (2400 MHz) and also
harmonic components at 20 kHz intervals due to the
fact that the outputs from the RF are not phase
matched. It is also evident that although the array was
modulated with an equal mark-space ratio switching
waveform, even harmonics are present in the
spectrum. However the even harmonics are at a low
level (more that 25 dB below the unmodulated
fundamental) and may be attributed to a combination
of many factors including a non-ideal switching
waveform and small differences in the amplitudes of
the signals radiating from the two monopoles. With
the array still orientated at broadside the line stretcher
was adjusted until the harmonics of the received
spectrum were minimized. With the array calibrated,
measurements of the received power levels were
recorded at the fundamental and the first harmonic
frequency over an angular range of +/-90 deg and 270
deg. To obtained from a simple model based on array
factor.
III. CONCLUSION
While in the presence of a two element time-
switched array system have been proposed. The
signals to each element of the array are time switched
to provide a phase modulated output signal in which
the depth of modulation is dependent on the angle of
arrival of the received signal. The angular response to
the array at the fundamental frequency of the
received signal exhibits a directional response at
broadside, while the response at the first harmonic of
the switching frequency exhibits a deep null.
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