Chapter 4: Test Results
4.1 Graphs and Plots
A trial of the OFDM MATLAB Simulation (Screen Log)
Figure 4.1: Screen Log
Transmitter Plots
One carrier can modulate only certain amount of symbols from one frame. The Figure 4.2 shows that for IFFT size of 1024 and with 497 carriers there are 17 symbols from one frame that are being modulated by one carrier. For differential phase shift keying, when mapping of the symbols to the phases is done then amplitude is taken to be constant. As shown in the Figure 4.3, for QPSK there will be four phases. The graph in Figure 4.4 shows that IFFT bins are almost utilized fully by the carriers.
Figure 4.2: Total Symbols Carried
Figure 4.3: Carriers designated on IFFT bins Figure 4.4: Transmitted Phases
Receiver Plots
When the signal after modulation is transmitted over the AWGN channel, it can be introduced with certain noise and amplitude clipping can take place as shown in Figure 4.5. In QPSK the phases have a 45 tolerance. With pixel percentage error being 5%, the noise is easily observable on the output image but information content received is highly usable. A sign of QPSK being successful is shown in the graph in Figure 4.6 with four groups of constellations.
Figure 4.5
Figure 4.6
It makes sense to have the values somewhat scattered. Figure 4.7 shows that the amplitudes of the received data are not as flat as the original.
Figure 4.7
By keeping all the parameters same and just changing the modulation technique, the simulation runtime for both the transmitter and receiver is plotted (figure 4.8) and it found to be almost the same. This is because the total number of frames did not vary mu...
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...n, James Cook University, Australia, Dec 2001
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A TV signal is captured by a camera and then manipulated during program production. At this point the video must be at its highest quality and full bandwidth for recording, editing and special effects purposes. Then the TV signal needs to be compressed for economical transmission and storage. The possible efficiency of compression depends on a couple of factors. If a signal will be further edited and manipulated in the receiving studio it must maintain a relatively high quality and therefore can’t be compressed as much as a signal that will be sent directly to the viewer’s TV set. Also, the extent to which a signal can be successfully compressed depends on the type of program (E.g. movies can be compressed more than sports). Nevertheless, a typical program mix will fit up to 10 digital television channels on one transmission line.
"Short History of Radio A Short History of Radio With an Inside Focus on Mobile Radio." fcc.gov. Version 2003-2004. N.p., n.d. Web. 4 Dec. 2013. .
For amplitude modulation the height or amplitude of the wave is changed to contain information. Amplitude modulation is not only used by radio stations but it is also used to send the picture part of television.
Analysis of the Environment of the Mobile Network System Executive Summary 3 Glossary of Abbreviations 4 Introduction 5 Recent History
Ash, J. D. (2007, December). Next generation SDH: Does it have a role in future packet-based wireline networks? Journal of Telecommunications Management, 1(2), 189.
The uses of Digital Signal Processing in communications has become so large scale that nearly any form of analog communication is considered obsolete. Today, nearly any form of communication used, aside from verbal communication, relates to Digital Signal Processing. Some of the more prominent uses for DSP in communications are; local area networks, cell pho...
The Digital Video Recorder used in modern entertainment systems can now be replaced with an easy to use streaming video devices. As the online video libraries grow to include more content, eventually streaming set top boxes will provide this functionality, without the need to schedule recordings or manage space used by previous recordings. One additional advantage, often referred to as TV Anywhere, allows viewing of online content from a variety of devices, as long as an Internet connection is available. Now the real motivation that drives many Americans to consider these alternative options is money.
We can use Public Switched Telephone Network (PSTN) as an example to explain the relationship between the data rates of the inputs and output of a TDM. Hanrahan (2005) indicates that there exists the need to transmit multiple subscribers’ calls along the same transmission medium. To meet the requirement, TDM is used because TDM allows switches to create channels within a transmission stream. If an input is a standard DS0 voice signal has a data bit rate of 64 Kbit/s, TDM takes frames of the voice signals and multiplexes them into a TDM frame which runs at a higher bandwidth. In other words, if the TDM frame consists of n voice frames, the bandwidth will be n*64 Kbit/s.
Sharma, Prashant , “Basic Facts About WiFi and Its Advancements”, 2 December 2008 , TechPluto, 19 May 2010 ,
Analog communication employs continuous transmission of an electromagnetic wave form that varies in frequency and amplitude.
Print. The. Gordon A. Gow, and Richard K. Smith. Mobile and wireless communications: an introduction, McGraw-Hill International, 2006. Print.
In a mobile communications network, part of the transmission connection uses a radio link and another part uses 2Mbit/s PCM links. Radio transmission is used between the Mobile Station (MS) and the Base Transceiver Station (BTS) and the information must be adapted to be carried over 2Mbit/s PCM transmission links throughout the remainder of the network.
Synchronization: The receiver is able to determine when a signal begins to arrive and when it has finished. It must also know the duration of the each signal.
b) Information cannot be shared at a wider range to different receivers at distanced locations
Ham radios are the communication tools used by a large number of people across the world to connect with their friends. Ham radios are used universally for communication purposes; however, despite being outdated, these radios have still not lost their essence. Therefore, in order to provide a manual regarding its use, this book, Ham Radio Guide: Quick Start Ham Radio Guide- from Beginner to advanced, has been written.