8393 research outputs found
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CDMA IN RURAL COMMUNCATION
No full textIn this project , the (Transmission – Channeling - Reception) systems have been simulated in the urban and rural areas. Those areas differ in the geographical structure and in the number of population. That’s why simulation of CDMA telecommunication system is different.Recently the number of users of the telecommunication system has been increased
especially in the cellular mobile communication system. Also, the services needed by the
subscribers have been increased. This necessitates increasing the bandwidth of the system
to transmit the largest amount of information.
Wide-Bandwidth increases the noise which reduces the amount of transmitted
information. As a result, new technologies required to solve this problem are innovated.
This new technology is Code Division Multiple Access (CDMA).
CDMA technique is designed to solve the increasing demand of the telecommunication
services which is considered the best techniques in wireless communication.
CDMA system is interference limited; therefore interference reduction must be
performed to obtain an acceptable quality of service and capacity. The entire interference
is occurred at the wireless channel, so the analysis and maintenance must be focused on
it.
In this research, the (Transmission – Channeling - Reception) systems have been
simulated in the urban and rural areas. Those areas differ in the geographical structure
and in the number of population. That’s why simulation of CDMA telecommunication
system is different.
Matlab 7 has been used as a tool of simulation which is a powerful mathematical tool
supported special toolbox and functions used intensively in the analysis of
telecommunication systems.
Simulation and modeling of the urban area have been obtained using Rayleigh Model to
simulate the fading channel and Rician Model for the simulation of rural area. Results
obtained in both cases have been analyzed and compared
Design And Implementation Of A Signal Generator Using Microcontroller
No full textThis thesis discusses the development process and the common features of a microcontroller based signal generator which allows the user to select a waveform type (sine, square, sawtooth and triangle) and to select the waveform frequency and amplitude.Signal generator that generates different shapes of waveforms over a wide range of frequencies, is an important instrument in testing and operating different kinds of electrical equipments. It can provide a wide range of controlled amplitudes, and maintain constant amplitude as the frequency is varied. It is widely used in engineering applications especially in control field. This thesis discusses the development process and the common features of a microcontroller based signal generator which allows the user to select a waveform type (sine, square, sawtooth and triangle) and to select the waveform frequency and amplitude. Many hardware and software tools are involved in the design of the signal generator. Microcontroller is used to generate the signal and to display the frequency and the amplitude of the generated signal
Design and implementation of Software Defined radio transceiver
No full textThe project is design and implement a soft ware defined radio transceiver.Our project was to design and implement a soft ware defined radio transceiver.
The Software Defined Radio (SDR) is a collection of hardware and software technologies
that enable reconfigurable system architectures for wireless networks and user terminals.
SDR provides an efficient and comparatively inexpensive solution to the problem of
building multi-mode, multiband, multi-functional wireless devices that can be enhanced
using software upgrades. SDR technology facilitates implementation of some of the
functional modules in a radio system such as modulation/demodulation, signal generation
and coding in software. This helps in building reconfigurable software radio systems
where dynamic selection of parameters for each of the above-mentioned functional
modules is possible. Operators and service providers, SDR can have substantial impacts.
First, it reduces costs by providing a generic hardware platform and common product
line, which can then be customized for any unique application.
The aim of this project was to get the benefit of using software defined radio.
Firstly we designed a model consist of SDR transmitter and receiver. We implement our
software part using the matlab program and the matlab gave good result. This thesis give
a detailed description about the SDR designed model, steps used to implement the
software part and the analysis of the results
HOUSEHOLD APPLIANCES CONTROL FOR DISABLED PERSONS
No full textThe goal of this project is design low-cost device and easy to use for physically disabled people with limited mobility who they cannot move to operate electrical household appliances so they need a simple device that allow them to control these appliances without needing help.Remote control is having a great impact in making life easier; it is a device has an ability to control apparatus from a distance by means of signals. In this project we presented design of a simple universal remote control that have the ability to control multiple electrical devices. The goal of this thesis is design low-cost device and easy to use for physically disabled people with limited mobility who they cannot move to operate electrical household appliances so they need a simple device that allow them to control these appliances without needing help. The universal remote control is the solution from this problem, this thesis discuss the design and implementation of the universal remote control using USART protocol that provide serial transmission of the commands that operate the electrical devices from the transmitter to the receiver device, these commands are transmitted using infrared radiation emitted by the IR led transmitter and received by IR sensor. The system based on microcontrollers so sit offers the advantage of having small size, light weight and portability which provide the simplicity and the ease of use. The efficiency of this system could be improved by further optimizations. Also further work is needed to improve the system and more devices can be added to be controlled and operated
Routing in Multi-hop Ad hoc Wireless Networks
No full textThe objective of this thesis includes:
Understand the concept of ad hoc networks.
Studying the mechanism of Ad Hoc routing protocol and the literatures are basis of
this study The three routing protocols which are being investigated, are
Destination-Sequenced Distance-Vector routing (DSDV), Ad Hoc On-demand
Distance Vector routing (AODV) and Dynamic Source Routing (DSR).
The simulation environment will be conducted with the Linux operating system whereby
it is possible to experiment with the impact on these routing protocols in different node
mobility conditions, loading as well as node density.An ad hoc network is a collection of wireless mobile nodes dynamically forming a
temporary network without the use of any existing network infrastructure or centralized
administration.
Due to the limited transmission range of wireless network interfaces, multiple network
"hops" my be needed for one node to exchange data with another across the network. The
mobile nodes perform both as a host and a router forwarding packets to other nodes.
Because of the nature of ad hoc networks, there are special demands for ad hoc routing
protocols, also the performance of these routing protocols is an interesting issue. Many
different protocols have been proposed to solve the multihop routing problem in ad hoc
networks, each based on different assumptions and intuitions.
This thesis presents a simulation and performance evaluation analysis of three various
routing protocols that have been proposed for the Mobile Ad Hoc Network (MANET)
environment using the Network Simulator-2 (NS-2) tool, the protocols are: Ad-Hoc on-
Demand Distance Vector protocol (AODV), Dynamic Source Routing (DSR), and
Destination- Sequenced Distance Vector routing protocol (DSDV).
By using NS-2 the performance metrics of the routing protocols were analyzed such as
packet delivery ratio, routing overhead and average end-end delay, the performance of
the routing protocols in varied mobility speed as well as loading conditions have been
studied.
The results of the simulation show that the ability of DSDV to deal with dynamic
topology is very poor. This protocol should be avoided when it is crucial to deal with
frequent changes in topology. However this protocol is good for networks where the
nodes are static for long periods of time.
DSR was very good at all mobility rates and movement speed; it shows very good
performance and should be used where high mobility is concerned. Finally AODV
performs almost as well as DSR at all mobility rates and movement speeds. This protocol
is another choice in high mobility networks
New locality record of the variegated butterfly bat, Glauconycteris variegata (Tomes, 1861) from the Sudan
No full text7 pages (41-47)SJS 6(1) 2014Two adult male specimens of small vespertilionid bats were collected from Khartoum and two males from the Dinder National Park (DNP), by mist nets. The collected specimens were identified as Glauconycteris variegata. Males of G. variegate collected from Khartoum are found to be larger than males collected from the DNP in six measured morphometric characters and have the base of their wings and their interfemoral membrane orange in colour. The males G. variegatus were found roosting in the riverine area in Khartoum and DNP. One specimen was found roosting with a colony of Scotophilus nigrita, G. argentata and Rhinolophus landeri in a well in the DNP
Trends and variations in the activity of global vegetation in response to climate variability between 1987 and 1997
No full text10 pages (11-21) SJS 6(1) 2014Eleven-year (1987-1997) time series data of remotely sensed vegetation index (NDVI) and meteorological observations (temperature, precipitation, cloud cover and relative humidity) provided a powerful tool to illuminate the response of global terrestrial vegetation to short-and long-term climate variability. NDVI being a sensitive estimator of the amount of photosynthetic active radiation intercepted by the canopy has been treated as a proxy for above ground net primary production (ANPP). Analyses of trends, multiple regression and correlation analyses were employed. The main result indicates a considerable increase (0.7~1.9%/year) of monthly vegetation production in all ecosystems over the investigated period, allied with an analogous increase (0.9~15%/year) in precipitation. Additionally, several direct relationships were also observed on the intra- and inter-annual time scales suggesting that the increase and variation of ANPP in most biomes could be mainly linked to the corresponding increase and variation in precipitation. Overall, the four climate variables play a considerable role in the inter-annual variability of ANPP of global vegetation. المستخلص 7881 ( عبارة عن مؤشر النباتات - بيانات زمنية متسلسلة لأحد عشر عاما ) 7891 (NDVI) المستشعر عن بعد وبيانات الإرصاد الجوي )الحرارة، الهطول، السحب و الرطوبة النسبية( قدمت أداة فعالة لإلقاء الضوء على ردة فعل النباتات الارضية على التغيرات المناخية على المدى القصير و الطويل. تم التعامل مع مؤشر النباتات و الذي يمثل مقياس حساس لكمية طاقة التمثيل الضوئي النشطة المعترضة بواسطة الغطاء النباتي ليمثل الإنتاج الأولي على سطح الارض (ANPP) .تمت معالجة البيانات المتسلسلة زمنيا بإستخدام عدد من المعاملات الإحصائية مثل تحليل الميل، التراجع المتعدد و الإرتباط. النتيجة الرئيسية أوضحت أن هناك تزايداَ شهريا مقدرا ) 0.7~1.9%) ( في إنتاجية النباتات في كل الانظمة البيئية خلال فترة الدراسة منسجما مع زيادة موازية في كمية الهطول ) 0.9~15% (. بالإضافة للعديد من العلاقات الطردية على المقاييس بين و خلال السنوية مما يقترح أن الزيادة و التباين في ال ANPP في أغلب البيئات النباتية مرتبط بزيادة أو تباين موازيين في معدلات الهطول. عموما فإن المتغيرات المناخية الاربعة تلعب دورا مقدرا في التغيرات بين السنوية في معدلات الإنتاج الاولي للنباتات في العال
