the signal. In communication terminology‚ this is called multipath. Since the indirect paths take more time to travel to the receiver‚ the delayed copies of the signal interfere with the direct signal‚ causing ISI. OFDM can be seen as either a modulation technique or a multiplexing technique. One of the main reasons to use OFDM is to increase the robustness against frequency selective fading or narrowband interference. In a single carrier system‚ a single fade or interferer can cause
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reproduced‚ or distributed in anyway‚ without written consent of the Author. Contact: msharawi@go.com.jo or husamsamir@hotmail.com 1 To our Moms‚ and Dads. Abstract The aim of this project is to demonstrate three of the Digital Modulation schemes used these days in Communications‚ which are the FSK(Frequency Shift Keying)‚ the PSK(Phase Shift Keying)‚ and the QPSK(Quadrature Phase Shift Keying)‚ and to design the electronic circuits for these systems on a single PCB(Printed Circuit
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invented the triode vacuum tube. Commercial radio broadcasting began in 1920 when radio station KDKA began broadcasting amplitude-modulated (AM) signals out of Pittsburgh‚ Pennsylvania. In 1931‚ Major Edwin Howard Armstrong patented frequency modulation (FM). Commercial broadcasting of monophonic FM began in 1935. The decibel (abbreviated dB) is a logarithmic unit that can be used to measure ratios of virtually anything. Zero dB-SPL is the threshold of hearing. The threshold of pain
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Data transmission methods Transmission Transmission is the act of transporting information from one location to another via a signal. The signal may be analog or digital‚ and may travel in different media. Transmission: Communication of data by propagation and processing of signals. Signal processing is the representation‚ transformation and manipulation of signals plus the information they contain. Signal Types Signals: An electric or electromagnetic representations of data by which data is
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is intensity modulation (IM) and direct detection (DD). In VLC systems with intensity modulation (IM) and direct detection (DD)‚ the modulation bandwidth of light emitting diode (LED) is limited‚ and the dispersion of the channel might cause ISI. Therefore most modulation schemes cannot be used directly for such a system. This project aims to show that a multiple-input multiple output (MIMO) orthogonal frequency division multiplexing (OFDM) VLC system overcomes the modulation bandwidth limitation
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Mobile communications and digital signal processing. Introduction to mobile radio communications. Spread spectrum. Modulation techniques. Introduction. Mobile communication has seen an unprecedented increase in the number of users over the past years. Its success in part is due to the various technologies that have been developed. It is not unlike other stationary communication systems in many respects however it does differ in others‚ one obvious one being the environment the signal and
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1INTRODUCTION Are you tired of slow modem connections? Cellonics Incorporated has developed new technology that may end this and other communications problems forever. The new modulation and demodulation technology is called Cellonics. In general‚ this technology will allow for modem speeds that are 1‚000 times faster than our present modems. The development is based on the way biological cells communicate with each other and nonlinear
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information using a continuous signal which varies in amplitude‚ phase‚ or some other property in proportion to that of a variable. It could be the transfer of an analog source signal‚ using an analog modulation method such as frequency modulation (FM) or amplitude modulation (AM)‚ or no modulation at all. (Wikipedia) Until the 1950’s all voice communication was analog as invented by Bell and developed within the Bell system. Analog transmission is particularly susceptible to the above factors
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CHAPTER II THEORETICAL FRAMEWORK This Chapter presents the Relevant Theories‚ Related Literature and Studies‚ Conceptual Framework‚ Hypothesis and the Definition of Terms used in the study. Relevant Theories There are two theories which are considered relevant in this study‚ namely: Goal Setting Theory of Motiviation by Dr. Edwin Locke (1990)‚ and Cognitive Learning Theory. Goal Setting Theory states that goal setting is essentially linked to task performance. It states that specific
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Encoding methods and Modulation schemes 25.P.1 Computers use digital signalling‚ digitals signals are represented by the base 2 numbering system “Binary”. Binary bits are shown as 1 or 0‚ where 1 means ON and 0 means OFF. In a network where digital devices exist‚ digital signalling will be used. Dependant upon the encoding method used‚ a high voltage on a communications medium can represent a logical 1 and a low voltage of can represent a logical 0. Different methods of encoding exist these
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