Pub Date : 2007-11-05DOI: 10.1109/ICSCN.2007.350700
K. K. Gupta, R. Gupta
In this paper, a new wavelet shrinkage denoising algorithm is presented. The algorithm uses wavelet transform (WT) to extract information about sharp variation in multiresolution images and applies shrinkage function adapting the image features. The shrinkage function depends on energy of neighboring pixels, whereas in standard wavelet methods, the empirical wavelet coefficients shrink pixel by pixel, on the basis of their individual magnitude. Experiments show that wavelet shrinkage algorithm which uses neighboring pixels energy improves the denoising performance and achieves better peak signal to noise ratio compared to other thresholding algorithms. Due to its low complexity, the proposed algorithm is very suitable for hardware implementation
{"title":"Feature Adaptive Wavelet Shrinkage for Image Denoising","authors":"K. K. Gupta, R. Gupta","doi":"10.1109/ICSCN.2007.350700","DOIUrl":"https://doi.org/10.1109/ICSCN.2007.350700","url":null,"abstract":"In this paper, a new wavelet shrinkage denoising algorithm is presented. The algorithm uses wavelet transform (WT) to extract information about sharp variation in multiresolution images and applies shrinkage function adapting the image features. The shrinkage function depends on energy of neighboring pixels, whereas in standard wavelet methods, the empirical wavelet coefficients shrink pixel by pixel, on the basis of their individual magnitude. Experiments show that wavelet shrinkage algorithm which uses neighboring pixels energy improves the denoising performance and achieves better peak signal to noise ratio compared to other thresholding algorithms. Due to its low complexity, the proposed algorithm is very suitable for hardware implementation","PeriodicalId":257948,"journal":{"name":"2007 International Conference on Signal Processing, Communications and Networking","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124705907","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2007-11-05DOI: 10.1109/ICSCN.2007.350788
P. S. Pandian, Megha Singh, M. Kumaravel
The normalized back-scattered intensity (NBI) profiles at various locations on the human thorax of a subject were obtained by multi-probe laser reflectometer. The laser radiations are guided by an optical fiber onto the human thorax tissues and the backscattered radiations are collected by three optical fibers placed at distance of 2 mm, 4 mm and 6 mm from the input fiber. The data collection of the human thorax tissue is carried out using an automatic non-contact scanning system controlled by the personal computer. The data after digitization, interpolation and filtering, are color-coded and displayed on the outline of the human thorax. These NBI pattern vary depending on the muscular, anatomical and vascular compositions and also on percentage of fat composition at various locations. For optical characterization the optical parameters, scattering (mus) and absorption (mua) coefficients and the anisotropy parameter (g) at each location on the human thorax, by matching of reflectance profiles with that as simulated by a Monte Carlo simulation (MCS) procedure were determined. The point-to-point variations of the optical parameters and NBI variations at various regions of the human thorax tissues are studied
{"title":"Non-Invasive Imaging and Characterization of Human Thorax Tissues by Non-Contact Scanning Multi-Probe Laser Reflectometry and Monte Carlo Simulation","authors":"P. S. Pandian, Megha Singh, M. Kumaravel","doi":"10.1109/ICSCN.2007.350788","DOIUrl":"https://doi.org/10.1109/ICSCN.2007.350788","url":null,"abstract":"The normalized back-scattered intensity (NBI) profiles at various locations on the human thorax of a subject were obtained by multi-probe laser reflectometer. The laser radiations are guided by an optical fiber onto the human thorax tissues and the backscattered radiations are collected by three optical fibers placed at distance of 2 mm, 4 mm and 6 mm from the input fiber. The data collection of the human thorax tissue is carried out using an automatic non-contact scanning system controlled by the personal computer. The data after digitization, interpolation and filtering, are color-coded and displayed on the outline of the human thorax. These NBI pattern vary depending on the muscular, anatomical and vascular compositions and also on percentage of fat composition at various locations. For optical characterization the optical parameters, scattering (mus) and absorption (mua) coefficients and the anisotropy parameter (g) at each location on the human thorax, by matching of reflectance profiles with that as simulated by a Monte Carlo simulation (MCS) procedure were determined. The point-to-point variations of the optical parameters and NBI variations at various regions of the human thorax tissues are studied","PeriodicalId":257948,"journal":{"name":"2007 International Conference on Signal Processing, Communications and Networking","volume":"156 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134433996","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2007-11-05DOI: 10.1109/ICSCN.2007.350686
B. V. Dhandra, M. Hangarge, R. Hegadi, V. S. Malemath
India is a multi-lingual and multi-script country where a line of a bilingual document page may contain text words in regional language and numerals in English. For optical character recognition (OCR) of such a document page, it is necessary to identify different script forms before running an individual OCR of the scripts. In this paper, we examine the use of discriminating features (aspect ratio, strokes, eccentricity, etc,) as a tool for determining the script at word level in three bilingual documents representing Kannada, Tamil and Devnagari containing English numerals, based on the observation that every text has the distinct visual appearance. The k-nearest neighbour algorithm is used to classify the new word images. The proposed algorithm is tested on 2500 sample words with various font styles and sizes. The results obtained are quite encouraging
{"title":"Word Level Script Identification in Bilingual Documents through Discriminating Features","authors":"B. V. Dhandra, M. Hangarge, R. Hegadi, V. S. Malemath","doi":"10.1109/ICSCN.2007.350686","DOIUrl":"https://doi.org/10.1109/ICSCN.2007.350686","url":null,"abstract":"India is a multi-lingual and multi-script country where a line of a bilingual document page may contain text words in regional language and numerals in English. For optical character recognition (OCR) of such a document page, it is necessary to identify different script forms before running an individual OCR of the scripts. In this paper, we examine the use of discriminating features (aspect ratio, strokes, eccentricity, etc,) as a tool for determining the script at word level in three bilingual documents representing Kannada, Tamil and Devnagari containing English numerals, based on the observation that every text has the distinct visual appearance. The k-nearest neighbour algorithm is used to classify the new word images. The proposed algorithm is tested on 2500 sample words with various font styles and sizes. The results obtained are quite encouraging","PeriodicalId":257948,"journal":{"name":"2007 International Conference on Signal Processing, Communications and Networking","volume":"174 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133319817","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2007-11-05DOI: 10.1109/ICSCN.2007.350662
P. Sathish, P. Vanaja Ranjan, S. Solai Manohar
Now-a-days automated and interconnected process as in distributed control system requires a very reliable communication. The serial communication protocol called CAN (controller area network) is taken into account and is made more reliable by introducing additional fault confinement mechanisms. Since actual CAN protocol is bus topology based in which multiple components (direct electrical connection between the nodes) are present, its use in safety critical application is not recommended. So active star topology based CAN protocol is proposed, which needs the design of respective hub that could enforce confinement of faulty nodes thus avoiding any severe failure of communication. In future the hub with its fault tolerant mechanism is to be implemented in FPGA and further can be realized as an ASIC
{"title":"A New Approach for Fault Confinement in CAN-Network","authors":"P. Sathish, P. Vanaja Ranjan, S. Solai Manohar","doi":"10.1109/ICSCN.2007.350662","DOIUrl":"https://doi.org/10.1109/ICSCN.2007.350662","url":null,"abstract":"Now-a-days automated and interconnected process as in distributed control system requires a very reliable communication. The serial communication protocol called CAN (controller area network) is taken into account and is made more reliable by introducing additional fault confinement mechanisms. Since actual CAN protocol is bus topology based in which multiple components (direct electrical connection between the nodes) are present, its use in safety critical application is not recommended. So active star topology based CAN protocol is proposed, which needs the design of respective hub that could enforce confinement of faulty nodes thus avoiding any severe failure of communication. In future the hub with its fault tolerant mechanism is to be implemented in FPGA and further can be realized as an ASIC","PeriodicalId":257948,"journal":{"name":"2007 International Conference on Signal Processing, Communications and Networking","volume":"118 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116348947","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2007-11-05DOI: 10.1109/ICSCN.2007.350726
J. Dheeba, A. Padma
A novel adaptive noise cancellation algorithm using cascaded correlation neural networks is described. In the proposed algorithm the objective is to filter out an interference component by identifying the non-linear model between a measurable noise source and the corresponding immeasurable interference. In many situations a linear model performs outstandingly. However a linear model does not perform well for situations where nonlinear phenomena occur. Hence there is a need of nonlinear filtering approach. The neural networks have been a predominant technology for intelligent control for many years. The cascaded correlation neural network algorithm has the powerful capabilities of learning and adaptation. By virtue of the learning ability, neural networks can be adapted to constantly changing environments. Two inputs, single output cascaded neural networks are used to develop the system, which eliminates the random noise, which is mixed with the test signal. Results of simulation studies using different noise sources and noise passage dynamics show that superior performance can be achieved using the proposed techniques
{"title":"Intelligent Adaptive Noise Cancellation using Cascaded Correlation Neural Networks","authors":"J. Dheeba, A. Padma","doi":"10.1109/ICSCN.2007.350726","DOIUrl":"https://doi.org/10.1109/ICSCN.2007.350726","url":null,"abstract":"A novel adaptive noise cancellation algorithm using cascaded correlation neural networks is described. In the proposed algorithm the objective is to filter out an interference component by identifying the non-linear model between a measurable noise source and the corresponding immeasurable interference. In many situations a linear model performs outstandingly. However a linear model does not perform well for situations where nonlinear phenomena occur. Hence there is a need of nonlinear filtering approach. The neural networks have been a predominant technology for intelligent control for many years. The cascaded correlation neural network algorithm has the powerful capabilities of learning and adaptation. By virtue of the learning ability, neural networks can be adapted to constantly changing environments. Two inputs, single output cascaded neural networks are used to develop the system, which eliminates the random noise, which is mixed with the test signal. Results of simulation studies using different noise sources and noise passage dynamics show that superior performance can be achieved using the proposed techniques","PeriodicalId":257948,"journal":{"name":"2007 International Conference on Signal Processing, Communications and Networking","volume":"63 12","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134191226","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2007-11-05DOI: 10.1109/ICSCN.2007.350734
S. Padmavathi, S. Mercy Shalinie
In this paper, we have analyzed various parallel algorithms for solving knapsack problem and proposed an efficient approach for solving knapsack problem using an approximation algorithm. We also discussed the time complexity of different algorithm. Backtracking is not discussed here due to its inherent sequential property. The validity of the proposed algorithm is demonstrated on a worked out example and it shows the superiority of the proposed algorithm
{"title":"Analyzing Time Complexity of Parallel Algorithms for Knapsack Problem","authors":"S. Padmavathi, S. Mercy Shalinie","doi":"10.1109/ICSCN.2007.350734","DOIUrl":"https://doi.org/10.1109/ICSCN.2007.350734","url":null,"abstract":"In this paper, we have analyzed various parallel algorithms for solving knapsack problem and proposed an efficient approach for solving knapsack problem using an approximation algorithm. We also discussed the time complexity of different algorithm. Backtracking is not discussed here due to its inherent sequential property. The validity of the proposed algorithm is demonstrated on a worked out example and it shows the superiority of the proposed algorithm","PeriodicalId":257948,"journal":{"name":"2007 International Conference on Signal Processing, Communications and Networking","volume":"144 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133648799","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2007-11-05DOI: 10.1109/ICSCN.2007.350774
S. A. Nazeer, N. Omar, M. Khalid
Advances in face recognition have come from considering various aspects of this specialized perception problem. Earlier methods treated face recognition as a standard pattern recognition problem; later methods focused more on the representation aspect, after realizing its uniqueness using domain knowledge; more recent methods have been concerned with both representation and recognition, so a robust system with good generalization capability can be built by adopting state-of-the-art techniques from learning, computer vision, and pattern recognition. A face recognition system based on recent method which concerned with both representation and recognition using artificial neural networks is presented. This paper initially provides the overview of the proposed face recognition system, and explains the methodology used. It then evaluates the performance of the system by applying two (2) photometric normalization techniques: histogram equalization and homomorphic filtering, and comparing with euclidean distance, and normalized correlation classifiers. The system produces promising results for face verification and face recognition
{"title":"Face Recognition System using Artificial Neural Networks Approach","authors":"S. A. Nazeer, N. Omar, M. Khalid","doi":"10.1109/ICSCN.2007.350774","DOIUrl":"https://doi.org/10.1109/ICSCN.2007.350774","url":null,"abstract":"Advances in face recognition have come from considering various aspects of this specialized perception problem. Earlier methods treated face recognition as a standard pattern recognition problem; later methods focused more on the representation aspect, after realizing its uniqueness using domain knowledge; more recent methods have been concerned with both representation and recognition, so a robust system with good generalization capability can be built by adopting state-of-the-art techniques from learning, computer vision, and pattern recognition. A face recognition system based on recent method which concerned with both representation and recognition using artificial neural networks is presented. This paper initially provides the overview of the proposed face recognition system, and explains the methodology used. It then evaluates the performance of the system by applying two (2) photometric normalization techniques: histogram equalization and homomorphic filtering, and comparing with euclidean distance, and normalized correlation classifiers. The system produces promising results for face verification and face recognition","PeriodicalId":257948,"journal":{"name":"2007 International Conference on Signal Processing, Communications and Networking","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133322535","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2007-11-05DOI: 10.1109/ICSCN.2007.350763
S. Bose, S. Bharathimurugan, A. Kannan
Most intrusion detection systems for mobile ad hoc networks are focusing on either routing protocols or MAC layer traffic. This paper focuses on the design of a new anomaly detection system for each node of the network, which contains detection subsystem for MAC layer, routing layer and application layer. Audit data taken from MAC level/network level/application level from the traces in Glomosim and are preprocessed separately for each layer's detection subsystem. Feature data sets for each layer are selected from normal transactions. The detection subsystem contains normal profiles obtained from the feature vectors of training data sets. In our work, we used Bayesian classification algorithm, Markov chain construction algorithm and association rule mining algorithm for anomaly detection in MAC layer, routing layer and application layer respectively for effective intrusion detection. Test data obtained from the network traffic is feed in to the detection subsystems. If there is any deviation from normal behavior, it is considered as abnormal or anomaly based on predefined thresholds. Intrusion results from detection subsystems of all the three layers are integrated at local integration module and the final result is sent to the global integration module. Intrusion results are received also from the neighbor nodes and are sent to the global integration module for making a final decision
{"title":"Multi-Layer Integrated Anomaly Intrusion Detection System for Mobile Adhoc Networks","authors":"S. Bose, S. Bharathimurugan, A. Kannan","doi":"10.1109/ICSCN.2007.350763","DOIUrl":"https://doi.org/10.1109/ICSCN.2007.350763","url":null,"abstract":"Most intrusion detection systems for mobile ad hoc networks are focusing on either routing protocols or MAC layer traffic. This paper focuses on the design of a new anomaly detection system for each node of the network, which contains detection subsystem for MAC layer, routing layer and application layer. Audit data taken from MAC level/network level/application level from the traces in Glomosim and are preprocessed separately for each layer's detection subsystem. Feature data sets for each layer are selected from normal transactions. The detection subsystem contains normal profiles obtained from the feature vectors of training data sets. In our work, we used Bayesian classification algorithm, Markov chain construction algorithm and association rule mining algorithm for anomaly detection in MAC layer, routing layer and application layer respectively for effective intrusion detection. Test data obtained from the network traffic is feed in to the detection subsystems. If there is any deviation from normal behavior, it is considered as abnormal or anomaly based on predefined thresholds. Intrusion results from detection subsystems of all the three layers are integrated at local integration module and the final result is sent to the global integration module. Intrusion results are received also from the neighbor nodes and are sent to the global integration module for making a final decision","PeriodicalId":257948,"journal":{"name":"2007 International Conference on Signal Processing, Communications and Networking","volume":"76 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126127775","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2007-11-05DOI: 10.1109/ICSCN.2007.350742
R. Sudhakar, S. Jayaraman
Video compression takes the advent of spatial, temporal and psycho-visual redundancies. These redundancies can be compensated efficiently by transform, motion estimation/compensation and quantization respectively. The existing video coding standards (MPEG) use block based discrete cosine transform (DCT). In the DCT the input image needs to be blocked. So correlation across the block boundaries is not eliminated resulting in noticeable and annoying blocking artifacts. This is overcome by using wavelets. For better performance in compression, filters used in wavelet transforms should have the property of orthogonality, symmetry, short support and higher approximation order. Due to implementation constraints scalar wavelets do not satisfy all these properties simultaneously. Also compression scheme based on wavelets is slow. A new class of wavelets called 'multiwavelets' which possess more than one scaling filters overcomes this problem. The objective of this paper is to develop and propose an efficient video compression scheme which provides better quality, high compression and also faster. This is achieved by using multiwavelets for transform, kite cross diamond search (KCDS) algorithm for block matching and 'novel scheme' for quantization. Novel scheme is a combination of set partitioning in hierarchical trees algorithm (SPIHT) and set partitioning in embedded block coding (SPECK). Hence the name hybrid coding
{"title":"A New Video Coder using Multiwavelets","authors":"R. Sudhakar, S. Jayaraman","doi":"10.1109/ICSCN.2007.350742","DOIUrl":"https://doi.org/10.1109/ICSCN.2007.350742","url":null,"abstract":"Video compression takes the advent of spatial, temporal and psycho-visual redundancies. These redundancies can be compensated efficiently by transform, motion estimation/compensation and quantization respectively. The existing video coding standards (MPEG) use block based discrete cosine transform (DCT). In the DCT the input image needs to be blocked. So correlation across the block boundaries is not eliminated resulting in noticeable and annoying blocking artifacts. This is overcome by using wavelets. For better performance in compression, filters used in wavelet transforms should have the property of orthogonality, symmetry, short support and higher approximation order. Due to implementation constraints scalar wavelets do not satisfy all these properties simultaneously. Also compression scheme based on wavelets is slow. A new class of wavelets called 'multiwavelets' which possess more than one scaling filters overcomes this problem. The objective of this paper is to develop and propose an efficient video compression scheme which provides better quality, high compression and also faster. This is achieved by using multiwavelets for transform, kite cross diamond search (KCDS) algorithm for block matching and 'novel scheme' for quantization. Novel scheme is a combination of set partitioning in hierarchical trees algorithm (SPIHT) and set partitioning in embedded block coding (SPECK). Hence the name hybrid coding","PeriodicalId":257948,"journal":{"name":"2007 International Conference on Signal Processing, Communications and Networking","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121178090","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2007-11-05DOI: 10.1109/ICSCN.2007.350752
N. D. Doddamani, Harishchandra, A. Nandi
The performance of modern radar systems with active phased array antennas is mainly driven by the performance of the microwave T/R modules. To reduce the size, weight, cost and power consumption, as well as to achieve better phase and amplitude accuracies for realizing low sidelobe levels with an accurate beam steering, T/R modules, now-a-days, employ MMICs (monolithic microwave integrated circuits) for implementing transmit/receive chain. The L-band SPDT switch, 6-bit digital attenuator, 6-bit digital phase shifter have been designed using GAETEC Hyderabad 0.7 μm GaAs MESFET switch model to handle 30 dBm peak power. All the above components have been designed and simulated using Agilent ADS CAD tool interfaced with Academy Layout. The SPDT switch with insertion loss less than -1 dB, isolation greater than 60 dB and return loss better than 20 dB has been realized on a single 3.0 mm × 2.35 mm GaAs chip. A 6-bit digital attenuator has a 31.5 dB attenuation range in 0.5 dB increments; 2.5° phase error and return loss better than 15 dB. The 6 bits are cascaded to form a complete attenuator on a double 3.5 mm × 2.35 mm GaAs chip with 3 attenuator bits in each for a better yield. A 6-bit digital phase shifter with 9 dB insertion loss, return loss better than 15 dB has been realized on a two GaAs chips with size 4.0 mm × 2.35 mm and 3.0 mm × 2.35 mm and 3 phase bits in each chip for the better yield
现代有源相控阵雷达系统的性能主要取决于微波收发模块的性能。为了减小尺寸、重量、成本和功耗，以及实现更好的相位和幅度精度，通过精确的波束转向实现低旁瓣电平，现在的T/R模块采用mmic(单片微波集成电路)来实现发射/接收链。采用GAETEC Hyderabad 0.7 μm GaAs MESFET开关模型设计了l波段SPDT开关、6位数字衰减器、6位数字移相器，可处理30dbm峰值功率。利用Agilent ADS CAD工具与Academy Layout界面对上述各部件进行了设计和仿真。在单个3.0 mm × 2.35 mm GaAs芯片上实现了插入损耗小于-1 dB、隔离度大于60 dB、回波损耗优于20 dB的SPDT开关。6位数字衰减器以0.5 dB增量的衰减范围为31.5 dB;相位误差2.5°，回波损耗优于15db。6位级联在双3.5 mm × 2.35 mm GaAs芯片上形成一个完整的衰减器，每个芯片上有3个衰减器位，以获得更好的良率。在尺寸分别为4.0 mm × 2.35 mm和3.0 mm × 2.35 mm的GaAs芯片上实现了插入损耗为9db，回波损耗优于15db的6位数字移相器，每个芯片上有3个相位位，从而获得了更好的良率
{"title":"Design of SPDT Switch, 6 Bit Digital Attenuator, 6 Bit Digital Phase Shifter for L-Band T/R Module using 0.7 μM GaAs MMIC Technology","authors":"N. D. Doddamani, Harishchandra, A. Nandi","doi":"10.1109/ICSCN.2007.350752","DOIUrl":"https://doi.org/10.1109/ICSCN.2007.350752","url":null,"abstract":"The performance of modern radar systems with active phased array antennas is mainly driven by the performance of the microwave T/R modules. To reduce the size, weight, cost and power consumption, as well as to achieve better phase and amplitude accuracies for realizing low sidelobe levels with an accurate beam steering, T/R modules, now-a-days, employ MMICs (monolithic microwave integrated circuits) for implementing transmit/receive chain. The L-band SPDT switch, 6-bit digital attenuator, 6-bit digital phase shifter have been designed using GAETEC Hyderabad 0.7 μm GaAs MESFET switch model to handle 30 dBm peak power. All the above components have been designed and simulated using Agilent ADS CAD tool interfaced with Academy Layout. The SPDT switch with insertion loss less than -1 dB, isolation greater than 60 dB and return loss better than 20 dB has been realized on a single 3.0 mm × 2.35 mm GaAs chip. A 6-bit digital attenuator has a 31.5 dB attenuation range in 0.5 dB increments; 2.5° phase error and return loss better than 15 dB. The 6 bits are cascaded to form a complete attenuator on a double 3.5 mm × 2.35 mm GaAs chip with 3 attenuator bits in each for a better yield. A 6-bit digital phase shifter with 9 dB insertion loss, return loss better than 15 dB has been realized on a two GaAs chips with size 4.0 mm × 2.35 mm and 3.0 mm × 2.35 mm and 3 phase bits in each chip for the better yield","PeriodicalId":257948,"journal":{"name":"2007 International Conference on Signal Processing, Communications and Networking","volume":"38 3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122508071","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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