Iqbal S.,Space and Upper Atmosphere Research Commission SUPARCO |
Amin M.,Space and Upper Atmosphere Research Commission SUPARCO
International Conference on Space Science and Communication, IconSpace | Year: 2013
In this paper, an EMC design retrofit has been proposed for improving the compliance of unit housings in a space-borne systems in accordance with EMC standards followed in space industry i.e. MIL-STD-461E/F. It has been shown that by loading the slots in the housings with metal wires, the radiated emissions from the enclosure can be significantly reduced. One significant advantage of loading the slots with wires is that this technique can be adopted without making any additional design change in the housing or enclosure. Loading slots with multiple wires eliminates slot cavity resonances and emissions at cavity mode resonance frequencies can be reduced by as much as 70dBμV/m on average. The technique is useful at post fabrication stage of enclosure to eliminate the peaks at resonant frequencies and bring down the level of radiated emission below threshold values as defined by various standards. © 2013 IEEE.
Siddiqui M.Z.,Space and Upper Atmosphere Research Commission SUPARCO
Strain | Year: 2015
This article reports an important development related to the inverse characterization of material constitutive parameters using 2D optical displacement field measurements. The out-of-plane motion of the specimen, which has traditionally been considered detrimental to the accuracy of these experiments, is generally of two types: (a) a global out-of-plane rigid-body motion of the specimen relative to the camera and (b) out-of-plane deformations resulting from material heterogeneity or out-of-plane loads. In an earlier article, we proposed to partially relax the condition of no out-of-plane motion by allowing for (b) in 2D inverse procedures, in the context of finite element update method, and introduced a compensation strategy by redefining the cost function on the object plane of the acquisition system. The experimental errors due to (a) were assumed negligible. Here, we propose that the global rigid-body motion (a) may also be recovered within the inverse procedures, hence completely waiving the condition of strictly in-plane displacements for inverse problems. The recovery is achieved by identifying and including the possible modes of global rigid-body motion within the cost function together with careful selection of test configuration. The effects of individual rigid-body modes on the computed displacement fields are studied in detail and utilized as a guideline for selection of test configuration. The approach is fully demonstrated and validated by simulated as well as real experiments for determining elastic constants of isotropic and orthotropic materials using different experimental setups. Effects of improving the optimization routine, for cost function minimization, and experimental noise are also presented. © 2014 Wiley Publishing Ltd.
Riaz M.,Space and Upper Atmosphere Research Commission SUPARCO
Proceedings of the International Astronautical Congress, IAC | Year: 2013
This paper discusses the right to salvage under the Law of the Sea and Space Law, drawing comparisons and highlighting the differences between the two. It goes on to elaborate whether the basic principles of maritime salvage law should be adopted in space law and the possible legal impediments to it. Furthermore, it must be considered how far the existing treaties (The Liability Convention, etc) and the Space Debris Mitigation Guidelines facilitate in mitigating disputes related to salvage and space debris. It is important to ascertain the possibility of drafting a treaty on the right to salvage of space objects and whether it may prove to be useful in space debris remediation. ©2013 by the International Astronautical Federation. All rights reserved.
Siddiqui A.A.,Space and Upper Atmosphere Research Commission SUPARCO |
Hussain Pirzada S.J.,Space and Upper Atmosphere Research Commission SUPARCO
ICASE 2013 - Proceedings of the 3rd International Conference on Aerospace Science and Engineering | Year: 2013
In this paper, a new scheme to enhance security of wireless gateway node is presented. In proposed scheme, analysis of implementing counter with cipher block chaining message authentication code on field programmable gate array has been proposed. Preliminary results show that proposed scheme does not have application dependency and have potential to be integrated with any application of wireless sensor network. © 2013 IEEE.
Naeem U.,Space and Upper Atmosphere Research Commission SUPARCO |
Jawaid Z.,Space and Upper Atmosphere Research Commission SUPARCO |
Sadruddin S.,Space and Upper Atmosphere Research Commission SUPARCO
Proceedings of 2012 9th International Bhurban Conference on Applied Sciences and Technology, IBCAST 2012 | Year: 2012
In this paper two techniques employed for compensating the Doppler shift encountered in LEO satellite receivers are presented. These include the analog compensation technique involving the carrier tracking loop and the compressive receiver technique. The compressive receiver technique which involves precise detection of the rapidly time varying carrier frequency received by the satellite receiver is discussed in further detail. A compressive receiver with a center frequency of 100 kHz and a Doppler shift up to ±100 kHz is simulated on MATLAB to test the technique. © 2012 IEEE.
Mehmood M.,Space and Upper Atmosphere Research Commission SUPARCO
ICASE 2015 - 4th International Conference on Aerospace Science and Engineering | Year: 2015
Acquisition is the first task of any receiver used for positioning and navigation applications. The acquisition block of a GNSS receiver not only decides which satellite is present or not but also determines the carrier frequency and code phase of the satellite, if present. Therefore acquisition involves both detection and estimation processes, and it follows that the acquisition technique can be affected by factors involved in either detection or estimation processes. This paper discusses various factors that can be manipulated to improve the performance of the processes involved in acquisition. Digitized data at intermediate frequency (IF) was collected with a front end logger and was input to the software receiver. The software receiver implements different acquisition schemes by varying factors such as length of data, correlation time and number of blocks used for non-coherent integration. Factors related to the signal such as sampling frequency, IF and signal strength were also changed to analyze different acquisition schemes. The analysis provides a better understanding of the acquisition process and eventually leads to accurate and reliable positioning. © 2015 IEEE.
Pirzada S.J.H.,Space and Upper Atmosphere Research Commission SUPARCO |
Siddiqui A.,Space and Upper Atmosphere Research Commission SUPARCO
International Conference on Space Science and Communication, IconSpace | Year: 2013
In field of image processing and pattern recognition, the use of edges as a feature is significant for feature extraction owing to its simplicity and accuracy. Its areas of application vary from object recognition to satellite based terrain recognition. There are many edge detection techniques like the canny edge detector and Sobel edge detector etc. However, the quality of an efficient algorithm depends on its capability to generate well localized edges of real images. Noise is inherent in all real images. To reduce its effect, various smoothing low pass filters are used prior to edge detection. This work, compares edge detection based on bilateral filtering with canny edge detection technique for satellite Images. Bilateral filtering based edge detection not only generates well localized edges but also simultaneously reduces considerable noise from real life images. The results show that the bilateral filtering based edge detection provide better edge maps than other comparable techniques. © 2013 IEEE.
Siddiqui K.S.,Space and Upper Atmosphere Research Commission SUPARCO |
Baig M.A.,Space and Upper Atmosphere Research Commission SUPARCO
ICICT 2011 - Proceedings of the 4th International Conference on Information and Communication Technologies | Year: 2011
The main objective of this paper is to design a Triple modular redundancy test bench using FRAM (Ferroelectric RAM) based memory module for main driver of OBDH (On Board Data Handling) system of LEO (Lower Earth Orbit) Satellite that enables the fast detection of error in driver data when implied with FPGA (Field Programmable Gate Array) and provides more realistic and tolerant way of fault finding for Single Event Upset (SEU) in highly radiated space environment. The scope of paper embraces development of TMR test bench, software algorithms, functional simulations, timing simulations and conclusion of comparison of FRAM based memory module with EEPROM and Flash Memories. © 2011 IEEE.
Baig M.A.,National University of Sciences and Technology |
Piracha M.M.A.,Space and Upper Atmosphere Research Commission SUPARCO
ICET 2013 - 2013 IEEE 9th International Conference on Emerging Technologies | Year: 2013
WLAN is used for variety of applications. It has become the source of internet connectivity with a much higher data rates and is being successfully used at airports, university corridors, hotel lounges, hospitals, business centers and so on. Presently the most popular standards for WLAN being used are 802.1 T-b, g and n, in which standard 'n' provides much higher data rate. For higher data rate, much higher bandwidth is needed. In this paper we have investigated the suitability of simple microstrip antennas i.e.(Bow-tie antenna, Elliptical inset-fed antenna and Rectangular inset-fed antenna) for WLAN applications, in comparison of more complex antennas. The purpose for choosing three different types of simple antenna structures is to analyze the reduced complexity of design with better performance amongst three. We have found that we can obtain considerable results even with the use of simple antenna structures in terms of bandwidth as compared to results obtained in previous studies. Analysis has been performed to find the relative gain, and impedance bandwidth of the three antennas. © 2013 IEEE.
Mustafa S.K.,Space and Upper Atmosphere Research Commission SUPARCO |
Yasir S.,Space and Upper Atmosphere Research Commission SUPARCO
Proceedings of 2013 10th International Bhurban Conference on Applied Sciences and Technology, IBCAST 2013 | Year: 2013
Dielectric rod antenna (DRA) has been used as an alternate feed system for the reflector antennas. Simulated and measured radiation characteristics for dielectric rod antenna have been discussed and compared. It is a cylindrical Teflon rod tapered from the radiating end and fed by a circular metallic waveguide. Such antennas are being used for their manufacturing simplicity, light weight, broadband characteristics and relatively higher gain and directivity as compared to horn antennas. Antenna discussed here was actually designed and measured for Ku band (12-14GHz) but simulated results reveal that it can exhibit broadband characteristics and can cover the range beyond 10-30GHz at either end. © 2013 IEEE.