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Advances in Space Technologies, 2008. ICAST 2008. 2nd International Conference on

Date 29-30 Nov. 2008

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Displaying Results 1 - 25 of 37
  • [Front cover]

    Page(s): c1
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    Freely Available from IEEE
  • [Copyright notice]

    Page(s): ii
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    Freely Available from IEEE
  • Preface

    Page(s): iii
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    Freely Available from IEEE
  • Conference Committees

    Page(s): iv - vi
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    Freely Available from IEEE
  • Table of contents

    Page(s): vii - viii
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    Freely Available from IEEE
  • [Copyright notice]

    Page(s): ix
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    Freely Available from IEEE
  • Effects of deploying IMT-Advanced systems on fixed satellite services in the 3 400 – 3 600 MHZ frequency band in Pakistan

    Page(s): 1 - 5
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (64 KB) |  | HTML iconHTML  

    This paper investigates the effects of deploying International Mobile Telecommunication-Advanced (IMT-Advanced) systems in the 3 400 - 3 600 MHz frequency band in Pakistan. This allocation of C-band spectra is being used by Paksat-1 for fixed satellite services (FSS). In addition future Paksat satellite networks will use the same C-band spectra for their FSS. The sharing studies b/w IMT-Advanced systems and GSO satellite networks in FSS show the incompatibility between them. To provide protection of the FSS receive earth stations, some separation distance between the stations of the IMT-Advanced network and the FSS receive earth stations is required. This issue was also on the agenda for the World Radio Communication Conference (WRC-2007) meetings in Geneva under item 1.4. The final provisional acts of WRC-2007 states that the band 3 400 - 3 600 GHz is identified for potential use of IMT-Advanced systems in Pakistan. View full abstract»

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  • Design and development of attitude control system (ACS) using COTS based components for small satellites

    Page(s): 6 - 11
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (305 KB) |  | HTML iconHTML  

    This paper deals with the attitude control of small satellites using commercial off the shelf (COTS) components in order to keep the overall cost within financial constraints. The design involves the use of gyroscopes and digital sun sensors (DSS) for attitude determination while three reaction wheels have been employed as actuators. Two different control schemes, proportional & derivative (PD) and linear quadratic regulator (LQR), are applied. Attitude control algorithms have been developed and optimized using Matlab based simulations for different scenarios and PD controller has been finally selected due to better performance. Finally, attitude control algorithms have been embedded in hardware. Telemetry and Telecommand signals between on board computer (OBC) system and ACS are transmitted through the CAN bus. The performance of embedded system has been analyzed and the results obtained are very close to the simulations. View full abstract»

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  • Design, substrates comparison and fabrication of 8-element high gain microstrip patch antenna

    Page(s): 12 - 17
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (719 KB) |  | HTML iconHTML  

    In this paper, the design of single microstrip patch antenna at 2.5 GHz, simulated with different kind of substrate materials using HFSS will be discussed. Subsequent to the selection of the most desirable substrate based on simulated results, a design of 8 element microstrip patch antenna array at X-band (10 GHz) design and a comparison of simulated and experimental results will be discussed. Typically low-cost, low-weight microstrip base station antenna array with narrow beam forming capability are taken into account. In the small countries, where the small area is required to cover by the emission of microwave beams through satellite only the tight spotted areas have been covered. This patch antenna with narrow beam-width of approximately 20deg to 35deg are required to complete the satellite communication coverage. Our goal will be to design such an antenna having beamwidth of round about 20deg to 30deg in azimuth. Using three types of substrate materials FR4, GML1000 and RT/Duroid 5880, the single patch simulated and experimental results are compared in conclusion. View full abstract»

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  • Design, fabrication & testing of Low Noise Amplifier at Ku-Band

    Page(s): 18 - 23
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (12179 KB) |  | HTML iconHTML  

    Low noise amplifier (LNA) is used to amplify the received low power RF signals. A narrowband LNA is designed at the center frequency of 12.7 GHz with a gain of 10 dB, bandwidth of 72 MHz and noise figure of 3 to 4 dB. The design methodology required the analysis of the transistor, stability check and proper matching network selection for input and output. Ideal microwave amplifier equations are used to carry out the analytical treatment for the design. Advanced Design Software (ADS) is used to carry out simulations for the design and to see how the design is comparable to the specifications. The DC and AC simulations for the LNA are presented in the paper. Fabrication and testing of the LNA is also discussed. View full abstract»

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  • Improving the convergence rate of Blind Constant Modulus Algorithm by using short training sequence

    Page(s): 24 - 27
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (225 KB) |  | HTML iconHTML  

    This paper presents an idea for enhancing the convergence rate of the blind constant modulus algorithm which is used in spatial filtering (beam forming) of the users in a typical CDMA environment. The convergence rate is increased by initializing the weights of the CMA using a non-blind algorithm least mean squares (LMS) utilizing only a few samples of training sequence. Performance as well as convergence of the algorithm have been enhanced using this technique. Computer simulations are presented to show the improved performance of this technique. View full abstract»

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  • Analysis of G-shape antennas mounted on a CUBESAT

    Page(s): 28 - 32
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (216 KB) |  | HTML iconHTML  

    In this paper, the simulation of three monopole with G type structure is proposed consisting of one closed rectangular wire loop and one open rectangular wire loop with maximum horizontal and vertical dimensions approximately of L1 = L2 = L3 =.25lambda, h=202lambda, w = .1834lambda, l =.3487lambda and having wire radius of 2 mm. Each of the structure is analyzed on perfect ground and on CUBESAT and their various performance parameters such as gain, bandwidth and input impedance is determined. The three structures were designed at centre frequencies of 150 MHz, 180 MHz and 330 MHz. These have the bandwidth of 6%, 32.77% and 41.8%, gain of 3.757 dB, 2.691 dB and 2.774 db, having input impedance of 234.2+31.886i,55.905-10.93i and 54.633+7.39i at the resonant frequencies respectively when mounted on a CUBESAT. The software used to analyze and simulate the proposed antenna is numerical electromagnetic code (NEC) -Win PRO. The numerical results of the designed wideband antenna are presented and analyzed. View full abstract»

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  • Dynamic stability of multi-inertial system

    Page(s): 33 - 37
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (318 KB) |  | HTML iconHTML  

    Experience has shown that a considerable vibration, due to either hard or soft self-excitation, of the driven end mechanism has often led to many design modifications (through build and test cycle). Conventional techniques of representing driven end mechanism by a ldquoBlack Boxrdquo of lumped parameters fail to identify the source of such undesirable structural oscillations. To make a viable computer model, it needs a more realistic approach, i.e. representing driving and driven end explicitly in terms of the maximum possible number of represent able subsystems. The approach would, indeed, take comparatively more computer time and space but still would be cost effective in identifying the problem and determining a suitable compensation strategy if necessary. Conventional methods to determine system stability does not suit for highly interactive multi-inertial system as each structural element behave differently due to adjoining element. The paper describe AEW radar scanner which is highly interactive electromechanical non-linear system. The scanner has two aerial bodies employed at front and back of the carrier aircraft. Both make azimuth rotation in synchronization mode to cover 360 degree coverage. The elevation rotation is based on demand angle of 5deg degrees in single instance as and when demanded. State Space method is used to define all structural elements cascaded together to count for intra element effects. The paper presents a novel technique to determine dynamic stability; the tendency of their variables or components of a system to remain within defined and recognizable limits despite the impact of disturbances. View full abstract»

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  • Aero-hydrodynamics data archiving system

    Page(s): 38 - 41
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (191 KB) |  | HTML iconHTML  

    A concept of knowledge based aerodynamic design data categorized as an aerodynamic database archiving system is presented, maintaining such a state of the art data and documentation resource on a national scale is of vital importance from the viewpoint of data availability/interoperability, ensured reliability, upholding data standards and its safe handling and distribution. Efforts made locally for maintaining a repository of aero-hydrodynamic data, CFD database for validation and verification aspects along with ground tests and field test data is now required to be upgraded into an aero-hydrodynamics data archiving system, to serve the local design community. View full abstract»

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  • Non-reciprocal magnetoplasmic phase shifting structures for satellite sensors

    Page(s): 42 - 46
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (258 KB) |  | HTML iconHTML  

    With growing interest in satellite sensors applications in sub-millimeter wave regions, signal control techniques and components are becoming increasingly important at these frequencies. This requires the complete apprehension and characterization of modal and performance plane features of such non-reciprocal structures. Modal analysis for GaAs Magnetoplasma parallel plate waveguide and gyroelectric performance factor analysis for GaAs Magnetoplasma ridged parallel plate waveguide is presented. Modal analysis in the extra-ordinary wave resonance region for parallel plate waveguide after the inclusion of collision frequency loss in the characteristic equation results in the conversion of dominant mode to first higher order mode as the bias field is increased. GPF analysis for ridged waveguide configuration at 250 GHz results in optimum value of GPF when magnetoplasma semiconductor is in a superstrate position with low permittivity dielectric substrate below a half rigde height. View full abstract»

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  • Design & development of cold gas propulsion system for Pakistan Remote Sensing Satellite (PRSS)

    Page(s): 49 - 53
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (776 KB) |  | HTML iconHTML  

    This paper describes the work performed at the satellite research and development centre, Karachi to produce cold gas propulsion system for prototype of Pakistan Remote Sensing Satellite (PRSS), which is currently under development phase. This system mainly consists of one Aluminum 6061 propellant tank which stores 2 Kg of gaseous nitrogen as propellant at 100 bars. This tank is designed, developed and tested by structure/propulsion/thermal (S/P/T) section of SRDC-K. The nitrogen gas is supplied to eight 1 N Thrusters at a steady regulated pressure of 8 bars. It passes through a two-stage pressure regulator assembly, and a solenoid valve. Thrusters closing and opening time is less than 7 ms and specific impulse is 73 s. These thrusters are tested on Thrusters Static Bench developed by S/P/T section. This system has passed all the required qualification and acceptance tests. The cold gas propulsion system represents an important advance in propulsion technology suitable for small satellites. As a result of this work, the size, mass and power requirements has been reduced. View full abstract»

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  • Study the effect of ozone layer depletion on aircraft design at atmospheric region of Pakistan

    Page(s): 54 - 57
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (187 KB) |  | HTML iconHTML  

    Ozone is of considerable importance to mankind because of its role as a shield for the biosphere against the Ultraviolet (UV) radiation from the outer space, in particular from the sun. Due to a serious reduction of O3 content in the atmosphere, life-forms on the earth are exposed to a new hazard in the form of an increase of harmful solar UV radiation intensity at the sea level. Atmospheric scientists started taking serious notice of the development of ozone hole in early 1980s. One of the damages is embrittlement in the aircraft that is caused by exposure to UV radiation. Ultraviolet exposure also causes electrical changes in the form of resistively modified and optically affected changes both thermal characteristics and opacity. A particularly UV-sensitive element is the solar array. More specifically the solar cell cover glass and its attendant adhesive are subject to darkening. This results in reduced cell illumination and an enhanced operating temperature both being deleterious (harmful or lethal) to cell operation. In this communication our goal is to enumerate the effects of ozone layer depletion that results in the penetration UV radiation so that the damage of the material of aircraft can be estimated. This estimation may be useful for the characterization of air craft operation from the earth and loss of the earth protection shield. This kind of study also helpful for aeronautical engineers to select proper aircraft materials. View full abstract»

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  • Sensor network security issues at network layer

    Page(s): 58 - 63
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (86 KB) |  | HTML iconHTML  

    This paper presents an overview of the various vulnerabilities in WSN at network layer, and the defensive measures that can be taken against these threats. Resource limitations in the Wireless Sensor networks prevent us to directly apply the security mechanism of normal computer networks, a completely different set of security protocols exist for the sensor networks. Various security protocols for sensor networks have been evaluated against these vulnerabilities. Most of the attacks on some well known and widely used security protocols have been discussed, along with the possible countermeasures for these attacks. Some new emerging protocols have also been discussed in this context. Suitability of implementation of cryptographic techniques at the network layer has also been investigated for these severely resource constrained networks. View full abstract»

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  • Implementation and analysis of QPSK & 16QAM modulator & demodulator

    Page(s): 64 - 68
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (759 KB) |  | HTML iconHTML  

    In this paper we present a system design that incorporates the functionalities of a digital modulator/demodulator along with controlling features such as symbol generation, filtering, modulation, demodulation, phase and timing recovery for QPSK and 16 QAM modulation schemes. It is concluded that for a BER of 10-5 an Eb/No of 13.5 dB and 9.5 dB is required for 16 QAM and QPSK respectively. Simulation and analysis of QPSK and 16 QAM modulator and demodulator is done on MATLABreg with real time implementation on TMS320C6713 digital signal processing (DSP) Kit. View full abstract»

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  • Performance analysis of (63, 56) BCH code using Multipath Rayleigh Fading Channel on Spartan-3 FPGA

    Page(s): 69 - 73
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4061 KB) |  | HTML iconHTML  

    Performance analysis of (63, 56) binary BCH (Bose-Chaudhuri-Hocquenghem) [1], [4] code has been done through simulations of codec on Matlab (using multipath Rayleigh fading channel realization). Performance was then analyzed on Spartan-3 FPGA and a comparison was carried out. For hardware performance measurement, MHX-2400 2.4 GHz OEM transceiver system has been employed for RF transmission and reception with adjustable power level functionality. MHX-2400 system uses frequency hopped spread spectrum (FHSS) technology and is widely used for telemetry applications. The hardware experiment has been performed in a two story building to virtually simulate multipath phenomena and then the efficiency of codec system is analyzed. This paper explicitly analyses the (63, 56) BCH codec for channel coding applications in satellite and telecommunication systems. The (63, 56) BCH code has codeword length, n = 63 and data block size of, k = 56, rendering a high data rate of 1.125 (n/k) which is quite suitable for applications requiring greater data rate. View full abstract»

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  • Speech Recognition using Dynamic Time Warping

    Page(s): 74 - 79
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (140 KB) |  | HTML iconHTML  

    Speech Recognition is a technology enabling human interaction with machines. The design of a speech recognition system capable of 100% accuracy is far from solved. This paper describes an isolated word, speaker dependent speech recognition system capable of recognizing spoken words at sufficiently high accuracy. The system has been tested and verified on MATLAB as well as the TMS320 C6713 DSK with an overall accuracy exceeding 90%. The paper shows the memory efficiency offered by using speech detection for separating the words from silence and the improved system performance achieved by using Dynamic Time Warping while keeping in view the overall design process, supported by experimental results. In future, speech recognition can serve as a means of data interoperability and distribution by allowing a mobile user (client) to retrieve information from the data networks (GPRS, WEB) using a client server architecture. The satellite system can be used as a wireless medium for accessing the data network. View full abstract»

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  • Selection of an appropriate classification technique for coastal biomass mapping using high and low resolution dataset

    Page(s): 80 - 84
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2727 KB) |  | HTML iconHTML  

    Mangrove forest is an integral part of inter-tidal zone of the coastal environment extending throughout the tropics and subtropics of the world. There is a wide spectrum of economic and ecological utility of Indus delta mangrove forests, sixth largest man groves forest of 92 countries. Over the last decades, numerous classification techniques/software have been used to extract deltaic vegetation information through remotely sensed data. In the present research paper, two different techniques (maximum likelihood classification and subpixel classification) were applied at high and low resolution satellite data. The aim was to propose best classification technique for the mapping and management of coastal green gold. Study highlights the draw backs of traditional classification results at low resolution satellite dataset. Subpixel classification results applied on medium resolution image were satisfactory and comparable with maximum likelihood classification results at high resolution satellite data. View full abstract»

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  • Assessing readiness for national geospatial data clearinghouse-a milestone for SDI development in Pakistan

    Page(s): 85 - 90
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (206 KB) |  | HTML iconHTML  

    The term Spatial Data Infrastructure (SDI) has been defined and still being redefined. However, ultimate objective of SDI is to improve the availability and accessibility to interoperable multiple geospatial data for a wide range of user community. One of the preliminary requirements to improve the availability and accessibility to geospatial data is to know, who has what and where, of which quality and contents as well as what are the conditions to exploit it. All these generic but very important questions are possible to be addressed by establishing a data advertising, sharing, discovering, and dissemination system known as geospatial data clearinghouse. View full abstract»

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  • Planning water resource management in Pishin-Lora river basin of Balochistan using GIS/RS techniques

    Page(s): 91 - 97
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (154 KB) |  | HTML iconHTML  

    The recent drought (1998-2004) in water deficient province of Balochistan (the largest province of Pakistan) affected the availability of seasonal rainwater and vegetation cover. Analysis of the spatial rainfall computed through spatial interpolation of point rainfall depicted a reduction of about 53-85 percent and 66-90 percent in volumes of rainwater during summer and winter seasons of the drought period, respectively. Spatio-temporal analysis of the vegetation cover carried out through land cover classification of satellite images revealed a reduction of up to 31 percent in summer season and 5-7 percent in winter season vegetation cover in Balochistan during the drought period. In addition to the direct impacts of this period of dry weather, significant increase in the number of tubewells in order to overcome the water deficiency during recent drought in the province resulted in over-abstraction of groundwater, particularly in the Pishin-Lora river basin. An average lowering of water table by 1-20 m per year in Pishin-Lora river basin triggered the process of identification of potential recharge sites in this heavily populated river basin. A methodology to delineate the potential groundwater recharge zones by means of geographical information systems and remotely sensed datasets was devised and spatial analyses were conducted using surface slope, drainage network, lithology and settlements in Pishin-Lora river basin. The results showed that about 50 percent of the basin had medium to high potential for recharging groundwater and the potential recharge areas were identified as the active zones for implementation of artificial recharge mechanisms for enhancement of groundwater recharge. View full abstract»

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  • Understanding neotectonic induced surface deformation from drainage network using digital elevation models

    Page(s): 98 - 102
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2300 KB) |  | HTML iconHTML  

    Digital elevation models (DEMs) provide an opportunity to quantify surface deformation in terms of elevation and its derivatives. Darvaz strike-slip fault is a junction zone of the Tajik depression and the Northern Pamirs. The Pyanj River makes a right angle turn after crossing the Central Badakhshan and Henjvan fault system and runs parallel to the Darvaz fault to the southwest on leaving the Pamir to join the Amu River 300 Km southwest. The river profile analysis in this region using SRTM digital elevation model gives information about the tectonic influence on the local drainage network. We create area-slope plot in order to derive channel parameters like concavity and steepness indices that are related closely to surface uplift and deformation. The results show that the Kyzylsu-Surkhab-Vakhsh river system is disrupted by faulting in its middle and lower reaches where they finally join the Pyanj-Amu river system. It is also observed that the main control over the drainage system is tectonic uplift due to ongoing complex faulting because of frequents earthquakes in this region. The quaternary faults in the region control local drainages and the deflection of rivers and stream channels is a further evidence of the recent fault activity. This study can be improved by using high resolution imagery and GPS data. View full abstract»

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