Defence Electronics Applications Laboratory

Dehradun, India

Defence Electronics Applications Laboratory

Dehradun, India
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Porwal S.,Defence Electronics & Applications Laboratory | Khare S.,Defence Electronics & Applications Laboratory
IETE Technical Review (Institution of Electronics and Telecommunication Engineers, India) | Year: 2016

The huge availability of high-resolution geographical data using the space/air borne platforms has made it possible to create and visualize the three-dimensional (3D) model of any part on the Earth. The seamless visualization of the adjacent data in a mosaic manner not only requires the specialized techniques for data representation but also require sophisticated techniques of rendering to meet the requirements of certain applications like flight simulator, missile path animation. The high speed rendering of the 3D frames is the key requirement in such applications where each frame rendering time is bounded. This paper presents a novel technique for efficient representation of the geographical data covering the complete globe and a new methodology of rendering of 3D frames that guarantees each frame construction within the desired time bound. © 2016 IETE.


Kumar A.,Defence Electronics Applications Laboratory | Jassal B.,Graphic Era University
2016 International Conference on Emerging Trends in Communication Technologies, ETCT 2016 | Year: 2017

The concept of vector summation of a target response to two orthogonal polarized signals for enhancing its delectability, even under concealed conditions, have been demonstrated. A dual polarized 94 GHz radiometer mounted on a dual axis scanning systems has been utilized to collect the field data for the study of the concept. Emissivity gradient due to the presence of target embedded in a given background has been plotted in both orientation i.e. along x and y axis of the target using both horizontal and vertical polarization. Enhanced contrast due to vector summation of orthogonal polarization has been traced in both polarizations for concept validation. © 2016 IEEE.


Singh R.,Defence Electronics Applications Laboratory | Jassal B.,Graphic Era University
2016 International Conference on Emerging Trends in Communication Technologies, ETCT 2016 | Year: 2017

Correlation measure is an important indicator of the performance any code sequence family used for communication system. Frequency Hopping (FH) codes are similar in construction of Time Hopping (TH) codes used in Ultra Wide Band (UWB) communication systems. Since the development of TH codes is not yet fully established, in this paper an effort has been made to utilize FH code families as TH codes as the former are widely available in large numbers and have been dealt with in literature. This paper investigates the similarity between correlation properties of FH and TH codes. Lower bounds of auto correlation and cross correlation functions of TH codes have been derived and compared those with FH codes. It is found that the values of correlation functions for TH codes are higher than those for FH codes. This conclusion has been established through a case study using three well-established FH code sequence families. © 2016 IEEE.


Chaudhuri D.,Integration Center | Porwal S.,Defence Electronics Applications Laboratory
Defence Science Journal | Year: 2014

Low contrast and noisy image limits the amount of information conveyed to the user. With the proliferation of digital imagery and computer interface between man-and-machine, it is now viable to consider digital enhancement in the image before presenting it to the user, thus increasing the information throughput. With better contrast, target detection and discrimination can be improved. The paper presents a sequence of filtering operations in frequency and spatial domains to improve the quality of the thermal infrared (IR) images. Basically, two filters - homomorphic filter followed by adaptive Gaussian filter are applied to improve the quality of the thermal IR images. We have systematically evaluated the algorithm on a variety of images and carefully compared it with the techniques presented in the literature. We performed an evaluation of three filter banks such as homomorphic, Gaussian 5×5 and the proposed method, and we have seen that the proposed method yields optimal PSNR for all the thermal images. The results demonstrate that the proposed algorithm is efficient for enhancement of thermal IR images. © 2014 DESIDOC.


Sood N.,Defence Electronics Applications Laboratory | Sen P.,Defence Electronics Applications Laboratory
IEEE MTT-S International Microwave and RF Conference 2015, IMaRC 2015 | Year: 2015

This paper describes the design and implementation of phase locked oscillator (PLO) in radio front-end applying a combination of techniques to achieve increased tolerance for withstanding high vibration environment. Elements of a PLO that have been focused upon and optimized include the loop filter parameters such as loop bandwidth and phase margin and the reference oscillator section along with overall mechanical design and packaging. The loop filter of frequency synthesizer is optimized with a trade-off among various parameters and reference oscillator is realized using internal vibration isolators to achieve exceptionally stabilized spectral performance under high vibration condition. © 2015 IEEE.


Singh V.K.,Defence Electronics Applications Laboratory
IET Microwaves, Antennas and Propagation | Year: 2010

This study presents the design of a micromachined microstrip patch antenna at Ka-band frequencies. The design of the antenna is based on selective lateral etching by micromachining techniques to enhance the performance of a microstrip patch antenna on silicon (Si) substrate. In this design, the silicon material is removed laterally underneath the radiating patch to provide a cavity that consists of a combination of air and substrate in a defined ratio. The effect of the cavity is to produce a low effective dielectric region around the patch. The test results show superior performance over conventional designs where the bandwidth and efficiency have increased by as much as 50 and 25%, respectively. © 2010 The Institution of Engineering and Technology.


Chaudhuri S.D.,Defence Electronics Applications Laboratory | Singh M.P.,Defence Electronics Applications Laboratory | Mishra A.,Defence Electronics Applications Laboratory
2013 IEEE 2nd International Conference on Image Information Processing, IEEE ICIIP 2013 | Year: 2013

The performance of the most popular unsupervised clustering algorithm, k-means depends on the initial seed points. This paper proposes a mode based adaptive seed selection algorithm, which is used to improve the performance of Wishart segmentation for the segmentation of polarimetric synthetic aperture radar images. © 2013 IEEE.


Porwal S.,Defence Electronics Applications Laboratory
Defence Science Journal | Year: 2013

Three-dimensional visualization of the geographic data using a digital globe model has been an integral part of a modern GIS system. The visualization of the digital globe model presents many challenges not found in traditional terrain visualization system. The representation of the digital earth (globe) model is important to efficiently render the geographical data without any distortion either at equator or Polar Regions. This paper presents a uniform scheme for efficient quad tree based level-of-details (LOD) representation of the digital globe to minimize the distortion at Polar Regions and meets the requirement of fast frame rate rendering. © 2013, DESIDOC.


Arora M.K.,Indian Institute of Technology Roorkee | Bansal S.,Indian Institute of Technology Roorkee | Khare S.,Defence Electronics Applications Laboratory | Chauhan K.,Defence Electronics Applications Laboratory
Defence Science Journal | Year: 2013

Target detection is of particular interest in hyperspectral image analysis as many unknown and subtle signals (spectral response) unresolved by multispectral sensors can be discovered in hyperspectral images. The detection of signals in the form of small objects and targets from hyperspectral sensors has a wide range of applications both civilian and military. It has been observed that a number of target detection algorithms are in vogue; each has its own advantages and disadvantages and assumptions. The selection of a particular algorithm may depend on the amount of information available as per the requirement of the algorithm, application area, the computational complexity etc. In the present study, three algorithms, namely, orthogonal subspace projection (OSP), constrained energy minimization (CEM) and a nonlinear version of OSP called kernel orthogonal subspace projection (KOSP), have been investigated for target detection from hyperspectral remote sensing data. The efficacy of algorithms has been examined over two different hyperspectral datasets which include a synthetic image and an AVIRIS image. The quality of target detection from these algorithms has been evaluated through visual interpretation as well as through receiver operating characteristic (ROC) curves. The performance of OSP algorithm has been found to be better than or comparable to CEM algorithm. However, KOSP outperforms both the algorithms. © 2013, DESIDOC.


Chaudhuri D.,Defence Electronics Applications Laboratory
Defence Science Journal | Year: 2013

More and more images have been generated in digital form around the world. There is a growing interest in finding images in large collections or from remote databases. In order to find an image, the image has to be described or represented by certain features. Shape is an important visual feature of an image. Searching for images using shape features has attracted much attention. There are many shape representation and description techniques in the literature. Object classification often operates by making decisions based on the values of several shape properties measured from an image of the object. Shape analysis is a useful tool for recognition of an object. This paper treats various aspects that are needed to solve shape matching problems: choosing the precise problem of global contour and region based shape analysis, selecting the properties of the similarity measure that are needed for the problem and choosing the specific similarity measure to compute the similarity. © 2013, DESIDOC.

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