Some key functions implemented in the transmitter are modulation, filtering, encoding, and signal transmitting (to be elaborated)
|
|
- Samson Sanders
- 5 years ago
- Views:
Transcription
1 1
2 An electrical communication system enclosed in the dashed box employs electrical signals to deliver user information voice, audio, video, data from source to destination(s). An input transducer may be required if the source information is not represented by an electrical signal. For example, in your cell phone, a microphone is used as input transducer that converts speech (sound) to electrical voice signal which is the input electrical signal to the electrical communication system. Correspondingly, on the receiving side, after the electrical signal of the same format as the input electrical signal is extracted by the receiver, the output transducer (such as a speaker) converts the signal to the format suitable for the destination user or destination device. 2
3 The transmitter is responsible for converting the input electrical signal to a transmitted signal, an electrical signal suitable for propagating through the channel to be used to deliver the signal. For example, if the channel is a fiber optic link, the transmitted signal has to be optical (a special form of electrical signal) which entails a laser in the transmitter. If the channel is a wireless link, then the signal is typically a radio signal (another special form of electrical signal also known as electromagnetic wave) which requires a radio transmitter and an antenna in the transmitter block. Some key functions implemented in the transmitter are modulation, filtering, encoding, and signal transmitting (to be elaborated) On the receiving end of the communication system, the received signal is a weakened and possibly distorted version of the transmitted signal plus interference and noise. The receiver is responsible for removing as much as possible noise, interference, and distortion, and then for converting the signal back to the same electrical signal format as the input electrical signal. Some key functions implemented in the receiver are filtering, amplification, demodulation, decoding (to be elaborated) Remark: a channel may be shared by many simultaneous communications 3
4 A communication signal can be represented and displayed as a function of time, called signal waveform. Generally functions of time are not limited to signals within a communication system. There are a lot of functions of time encountered in real life: stock market index versus time, Evanston s temperature versus time, your weight versus time, a patient s pulses versus time, to name a few. There are two distinctive kinds of waveforms: analog waveform and digital waveform. Examples of analog waveform are those generated form voice, audio, and video. Examples of digital waveform are those generated form computer data and digitized voice/audio/video. 4
5 The most basic electrical signal is the sine wave, also called sinusoid. The sine wave or sinusoid is a mathematical function that describes a smooth repetitive oscillation. (Wikipedia) Shown in the slide is the waveform of a sine wave. Mathematically, it is a periodic function (i.e., it repeats after every period ) characterized by three parameters: amplitude, frequency, and phase. Phase is meaningful only when there are more than one sine wave involved. Amplitude indicates the peak value of the waveform, which represents the strength of the sine wave. Frequency stands for the oscillation rate (i.e., rate of moving up and down) of the waveform; it is equal to 1/T, T being the period. This is because: if the waveform repeats itself every T seconds, then it oscillates 1/T times per second. For instance, a 100-Hz sine wave oscillates 100 times per second, as it repeats every 1/100 of one second. Any communication signal is made up of sine waves of varying frequencies. 5
6 A familiar sine wave in practice: household 110-Volt AC voltage is a sine wave with an amplitude of 156 Volts and a frequency of 60-Hz 6
7 This slide is an illustration of two sine waves with different amplitudes and frequencies. Two sine waves are displayed on the same graph here, where the taller (thus stronger) sine wave has a lower frequency (i.e., it oscillates at a slower rate than the other sine wave), the other sine wave has a smaller amplitude but a higher frequency. 7
8 This slides shows an illustrative example of three sinusoids with the same amplitude, the same frequency, but different timings. All three sinusoids have the same strength (same amplitude), the same oscillation rate (the same frequency), but they are off in timing; that is, they are generated at different times. Note from high school math: the sine function takes angle as its argument, and is a periodic function with period 2 (radians) or 360 degrees. Therefore the timing difference between two sinusoids is quantified by an angle, called phase inside the sine function. Naturally, the value of the phase is between 0 and 2. In communication systems, we customarily define the range of the phase as from - and + instead. When there are multiple sinusoids present, their phases become important. In this example, the three sinusoids of equal strength add up to ZERO, that is, they cancel out completely. (This is an extreme example used to illustrate the importance of phase.) Multiple-path Fading: When multiple versions of the same radio wave carrying your cell phone signal arrive at the base station due to ground and building reflections, they are of different amplitudes and phases. This is known as multiple-path effect, which does not strengthen your signal s reception. On the contrary, it weakens it. 8
9 When all three parameters of a sine wave are included, the mathematical expression for a general sine wave is s(t) = A sin (2 f 0 t + ) The strength of a sine wave can also be expressed in terms of signal power P, which is related to amplitude A by P = A 2 /2. While the unit for amplitude is Volt (or V in short), the unit for power is Watt (or W in short). Note that the frequency and the phase of a sine wave have nothing to do with the power of the sine wave. Why are sine waves important for communication systems? 1. They are the fundamental components ( genes ) of any signal, analog or digital: voice, audio, video, data, Note: a single sine wave component of a signal is often referred to, simply, as a frequency component 2. They are used as carriers in most wired communication channels and all wireless communication channels for transmission of information-bearing signals 9
10 The key parameter of a sine wave that distinguishes it from other sine waves is its frequency. When a signal is decomposed into multiple sine waves of different frequencies, it can be displayed as a function of frequency called signal spectrum. For example, in this slide, a single sine wave with amplitude 5 Volt, frequency 4000 Hz and phase -160 is displayed in the frequency domain, i.e., as a function of frequency. There are two things to display versus the frequency: amplitude and phase. The display of the signal s amplitude against its frequency is called amplitude spectrum. The display of the signal s phase against its frequency is called phase spectrum. With an amplitude of 5 Volt, the power of the signal is 12.5 Watt. The display of the signal s power against it frequency is called power spectrum. In this simple example, each spectrum is a function of time with a single point because there is only one sine wave and thus one single frequency. We shall focus primarily on the amplitude spectrum when dealing with frequencydomain representation of a signal. Here an amplitude of 5 Volt is found in the signal at frequency 4000 Hz. Thus the amplitude spectrum in this example is simply a function of frequency with a single point (commonly displayed as a bar) at f=4000 Hz. 10
11 It may be hard to appreciate the usefulness of signal spectrum when there is only one single sine wave In this slide, a signal consisting of two sine waves is illustrated in the frequency domain, one of them has an amplitude A and frequency f A, the other B and f B. The amplitude spectrum now consists of two bars, one has an amplitude value A at frequency f A, the other has an amplitude value B at frequency f B. 11
12 Extending to a signal x(t) that is made up of three sine waves The amplitude spectrum now contains three bars located at frequencies 1000, 2000, and 4000 Hz, respectively. These bars will be referred to as spectral lines. The phase spectrum of the signal is also displayed and it also contains three bars, although one of the bars has a zero value (so the bar collapses to a dot ) in this case. 12
13 More generally, Fourier Theory asserts that any signal waveform (or any function of time), whether it is analog or digital, can be decomposed into sine waves of differing frequencies. The set of frequencies of the sine waves that make up this signal typically spans a range. The size of this frequency range is called the bandwidth of the signal, or signal bandwidth. When all the spectral lines (bars) are displayed within the bandwidth, they illuminates a shaped area in the frequency-domain plot. This outline of this shape is a function of frequency called the (continuous) signal spectrum. In the slide, A(f) and D(f) denote the amplitude spectra of the two waveforms. Both are functions of frequency. Shown on the right of this slides are examples of amplitude spectrum. The shapes of the spectra are not so important and have been drawn arbitrarily, while the frequency range and the bandwidth defined by the signal spectrum is the most informative. Almost all the original forms of information signals (voice, audio, video, baseband data) have a frequency range in the low frequency area. For example, voice has a frequency range: Hz, commercial broadcast AM audio: 0-5 khz, analog video: 0-6 MHz, and baseband data signal: 0-B Hz, where B is proportional to data rate (will be elaborated in a later chapter) Note: A spectrum analyzer is a device used to display the spectrum of a signal. 13
14 When a signal passes through a communication channel or an electronic device (e.g., an amplifier), the signal spectrum is filtered by the channel or device. Specifically, a communication channel/device does not treat all the sine waves that make up the signal equally. For convenience, in the sequel, filter will be used to represent any communication device. Mathematically, the frequency-selective behavior of the channel/filter is represented as a function of frequency (just like the amplitude spectrum of the signal) called frequency response. If a signal with amplitude spectrum X(f) is passed through a channel/filter with frequency response H(f), then the output of the channel/filter will be a signal with amplitude spectrum Y(f) = H(f) X(f) multiplication of two functions of frequency Filtering Effect: if H(f 1 ) = 0, then Y(f 1 ) = 0, no matter what X(f 1 ) is. That is, the sine wave component with frequency f 1 is removed when the channel or filter has a zero response at frequency f 1. If H(f 2 ) = 1, then Y(f 2 ) = X(f 2 ), that is, the sine wave component with frequency f 1 is passed without change. If H(f 3 ) = , then Y(f 3 ) = X(f 3 ), that is, the magnitude of the sine wave component with frequency f 3 is scaled by Essentially, H(f) serves as amplitude multiplier for input sine wave with frequency f. 14
15 The frequency response of a filter generally consists of three sub-ranges of frequencies: the passband, the stopband, and the transition band. Within the passband, the frequency response is at or near the peak; within the stopband, the frequency response is nearly zero; and within the transition band, the frequency response varies largely from high to low. Frequency components of the signal within the passband will pass through the channel/filter without significant losses; frequency components of the signal within the stopband will be removed almost entirely; frequency components of the signal within the transition band will be subject to distortion since they are multiplied by largely varying frequency responses. It is desired to fit the signal of interest inside the passband of the channel or of the filter such that the frequency components of the signal will not be subject to significant suppression. The width of the passband is thus called the channel bandwidth or filter bandwidth. A quality filter should have a nearly flat frequency response within its passband and a narrow transition band. 15
16 When a signal travels through any communication medium, wired or wireless, its strength declines as distance increases a phenomenon known as power attenuation. Over a communication channel or a filter, the ratio of the input power to the output power is defined as power loss. For example, if a signal is transmitted using 10 Watt of power, and its strength is reduced to 1 Watt at reception, the power loss introduced by the channel is L = 10W/1W = 10. The power gain is defined as G = 1/L. That is, a power loss of 10 amounts to a power gain of 1/10. A power amplifier has power gain larger than 1 and a power loss smaller than 1. In communication systems, power loss and power gain are commonly expressed in decibels (db). L and G can be converted to decibels by taking the log and then multiplied by 10. As a result, L = 100 = 20 db L = = 50 db L = 1 = 0 db (no loss) L = 2 = 3 db (power is halved) 16
17 The following refers to the right column of Slide 16: In any wired medium twisted pair copper wires, optical fiber, coax cables power loss L increases with distance exponentially. As a result, in decibels, the power loss L db increases linearly with distance. Thus for wired media, power loss in decibels greatly ease the computation when the distance increases or decreases. Power loss rating is thus expressed in terms of attenuation coefficient (e.g., in db/meter, db/30ft, db/km, etc.) for wired media. In a line-of-sight wireless medium, power loss L increases with distance squared. (Note: the loss in decibels does not help in computing power losses when the distance increases or decreases.) In an urban environment, the power loss through a wireless medium without line-of-sight increases with distance raised to the power of k, where k is between 2 and 5, practically. A higher power law represents a more severe loss. (Caution: power-law is not exponential) Besides distance, power loss also depends on frequency of the signal and the specific transmission medium. For example, higher-frequency radio waves generally suffer from higher power losses than their lower-frequency counterpart; thinner copper wires generally produce larger power attenuations than thicker copper wires; optical fibers offer much lower attenuations than copper wires/cables. 17
18 White noise is the most commonly used model for representing noise in communication systems. It is a random waveform whose power spectrum spreads across the entire useful frequency range in any medium where communication signals may exist. That is, there is no frequency region where noise level is less than the others. Typically, a filter is used at a communication receiver to remove the frequency components of noise that are outside the signal band, i.e., outside the frequency range of signal spectrum. The strength of noise is commonly represented by noise power (spectral) density N 0 expressed in Watt/Hz. The overall noise power that the received signal of interest is subject to, after the filtering, is thus P N = N 0 B where P N is in Watt, N 0 is in Watt/Hz, and B is in Hz. Let P s denote the received signal power (accounting for attenuation). The signal-tonoise ratio SNR = P s /P N is commonly used to represent reception quality of a communication system. Note: Power amplifier can boost P s but it can t boost the SNR. 18
19 Twisted pair phone wires was originally designed to support voice signals only. Its channel bandwidth (i.e., its passband) was treated as 4 khz (0-4 khz) then, enough to cover voice signals of all humans. Above 4 khz, the frequency response of twisted pair phone wires is lower and uneven. However, advanced electronics and digital signal processing technologies have made it possible to transport data signals over a less-than-desirable frequency range of the twisted-pair phone wires up to about 1.1 MHz. The usage of the higher-frequency band of these wires to send and receive data signals (known as DSL) does not conflict the legacy landline phone service (POTS) thus enabling the Telco to provide bundled voice and data services. 19
20 FYI: US cable TV spectrum allocation, Wireless EM frequency ranges, Optical fiber attenuation coefficient (db/km) versus wavelength. Wireless: higher frequency range more bandwidth available worst propagation characteristics (higher penetration loss, higher loss through rain/fog/cloud, etc.) Smaller wavelength thus smaller-sized antenna Optical fiber: three wavelength ranges (can be converted to frequency ranges by using c = f ) with low attenuation coefficients higher frequency response Fiber and laser samples. 20
21 The frequency response of a channel is practically imperfect: it is not flat enough (implying uneven frequency response) in the passband and it contains a transition band. As such, the signal is distorted because its sine wave components undergo different amplitude multipliers because of uneven frequency response within the signal bandwidth. This type of signal distortion caused by uneven frequency response of the channel is called linear distortion. The imperfect frequency response can be overcome by a technique called equalization : the idea is to feed the distorted signal into an equalizer a filter with a frequency response designed to equalize the channel frequency response. Mathematically, as shown in the graphical example, the product of the two frequency responses (multiplication of two functions of frequency) is an ideal frequency response: a constant within the frequency band of interest. 21
22 Another type of distortion called nonlinear distortion is not due to uneven treatment of different frequencies of the signal. In other words, it is not caused by imperfection of the frequency response of the channel. Recall that power attenuation is unavoidable when signal travels through a communication medium. As a signal waveform fluctuates, it strength rises and falls. If the channel attenuates stronger segments more than it does weaker segments, the received signal is distorted. This is called non-linear distortion. The phenomenon is analogous to the power gain unevenness of audio amplifiers: turning the volume too high results in distorted sound. For example, an 20-dB amplifier (x100) is supposed to boost audio signal by a power gain of G=100. But the output power of any audio amplifier is practically limited to a specified MAX output. Assume that the Max output of this 20-dB amplifier is 100 Watt. Then if the volume is tuned to an input level of say, 2 Watt, then the amplifier can produce a gain of at most 50. Thus, louder sound segments are amplified less than softer sound segments contrast is compromised. Typically, a channel has a linear operating range of input powers within which nonlinear distortion does not exist. Thus, the solution is to restrict the input power level such that it stays within the linear operating range of the channel. This represents one of the many power limitation factors in communication system and data network designs. 22
23 When applied to telephone communication systems, since different people speak with different loudness, the power compression algorithm used to restrict the input power level to the twisted pair telephone line has to account for that. In theory, we can identify the loudest person in the world and determine the scaling factor needed to lower his/her voice volume to the upper limit of the linear operating range of the telephone line and then apply that factor to all phone calls. Doing so will guarantee that everyone s voice is sufficiently suppressed to avoid nonlinear distortion. However, such an approach will render the soft talkers voice inaudible in the background of noise. Solution = companding: louder voices receive a high compression factor while lower voices receive a lower compression factor. To maintain contrast (since a person s voice volume rises and falls, the contrast conveys emotion), the compression process is reversed at reception with an expanding process using an inverse nonlinear function of the compression function. Note: the slope of the nonlinear curve at a given power level indicates the power gain offered by the device at that power level 23
Input electric signal. Transmitter. Noise and signals from other sources. Receiver. Output electric. signal. Electrical Communication System
Electrical Communication System: Block Diagram Information Source Input Transducer Input electric signal Transmitter Transmitted signal Noise and signals from other sources Channel Destination Output Transducer
More informationLecture Fundamentals of Data and signals
IT-5301-3 Data Communications and Computer Networks Lecture 05-07 Fundamentals of Data and signals Lecture 05 - Roadmap Analog and Digital Data Analog Signals, Digital Signals Periodic and Aperiodic Signals
More informationIntroduction to Telecommunications and Computer Engineering Unit 3: Communications Systems & Signals
Introduction to Telecommunications and Computer Engineering Unit 3: Communications Systems & Signals Syedur Rahman Lecturer, CSE Department North South University syedur.rahman@wolfson.oxon.org Acknowledgements
More informationOutline / Wireless Networks and Applications Lecture 3: Physical Layer Signals, Modulation, Multiplexing. Cartoon View 1 A Wave of Energy
Outline 18-452/18-750 Wireless Networks and Applications Lecture 3: Physical Layer Signals, Modulation, Multiplexing Peter Steenkiste Carnegie Mellon University Spring Semester 2017 http://www.cs.cmu.edu/~prs/wirelesss17/
More informationTerminology (1) Chapter 3. Terminology (3) Terminology (2) Transmitter Receiver Medium. Data Transmission. Direct link. Point-to-point.
Terminology (1) Chapter 3 Data Transmission Transmitter Receiver Medium Guided medium e.g. twisted pair, optical fiber Unguided medium e.g. air, water, vacuum Spring 2012 03-1 Spring 2012 03-2 Terminology
More informationCHAPTER -15. Communication Systems
CHAPTER -15 Communication Systems COMMUNICATION Communication is the act of transmission and reception of information. COMMUNICATION SYSTEM: A system comprises of transmitter, communication channel and
More informationMassachusetts Institute of Technology Dept. of Electrical Engineering and Computer Science Fall Semester, Introduction to EECS 2
Massachusetts Institute of Technology Dept. of Electrical Engineering and Computer Science Fall Semester, 2006 6.082 Introduction to EECS 2 Modulation and Demodulation Introduction A communication system
More informationData Communication. Chapter 3 Data Transmission
Data Communication Chapter 3 Data Transmission ١ Terminology (1) Transmitter Receiver Medium Guided medium e.g. twisted pair, coaxial cable, optical fiber Unguided medium e.g. air, water, vacuum ٢ Terminology
More informationPhysical Layer: Outline
18-345: Introduction to Telecommunication Networks Lectures 3: Physical Layer Peter Steenkiste Spring 2015 www.cs.cmu.edu/~prs/nets-ece Physical Layer: Outline Digital networking Modulation Characterization
More informationAnnouncements : Wireless Networks Lecture 3: Physical Layer. Bird s Eye View. Outline. Page 1
Announcements 18-759: Wireless Networks Lecture 3: Physical Layer Please start to form project teams» Updated project handout is available on the web site Also start to form teams for surveys» Send mail
More informationCS307 Data Communication
CS307 Data Communication Course Objectives Build an understanding of the fundamental concepts of data transmission. Familiarize the student with the basics of encoding of analog and digital data Preparing
More informationChapter 3. Data Transmission
Chapter 3 Data Transmission Reading Materials Data and Computer Communications, William Stallings Terminology (1) Transmitter Receiver Medium Guided medium (e.g. twisted pair, optical fiber) Unguided medium
More informationLecture 2 Physical Layer - Data Transmission
DATA AND COMPUTER COMMUNICATIONS Lecture 2 Physical Layer - Data Transmission Mei Yang Based on Lecture slides by William Stallings 1 DATA TRANSMISSION The successful transmission of data depends on two
More informationChapter-15. Communication systems -1 mark Questions
Chapter-15 Communication systems -1 mark Questions 1) What are the three main units of a Communication System? 2) What is meant by Bandwidth of transmission? 3) What is a transducer? Give an example. 4)
More informationIntroduction to Communications Part Two: Physical Layer Ch3: Data & Signals
Introduction to Communications Part Two: Physical Layer Ch3: Data & Signals Kuang Chiu Huang TCM NCKU Spring/2008 Goals of This Class Through the lecture of fundamental information for data and signals,
More informationCommunication Channels
Communication Channels wires (PCB trace or conductor on IC) optical fiber (attenuation 4dB/km) broadcast TV (50 kw transmit) voice telephone line (under -9 dbm or 110 µw) walkie-talkie: 500 mw, 467 MHz
More informationSignal Characteristics
Data Transmission The successful transmission of data depends upon two factors:» The quality of the transmission signal» The characteristics of the transmission medium Some type of transmission medium
More informationTerminology (1) Chapter 3. Terminology (3) Terminology (2) Transmitter Receiver Medium. Data Transmission. Simplex. Direct link.
Chapter 3 Data Transmission Terminology (1) Transmitter Receiver Medium Guided medium e.g. twisted pair, optical fiber Unguided medium e.g. air, water, vacuum Corneliu Zaharia 2 Corneliu Zaharia Terminology
More informationData and Computer Communications. Chapter 3 Data Transmission
Data and Computer Communications Chapter 3 Data Transmission Data Transmission quality of the signal being transmitted The successful transmission of data depends on two factors: characteristics of the
More informationPoint-to-Point Communications
Point-to-Point Communications Key Aspects of Communication Voice Mail Tones Alphabet Signals Air Paper Media Language English/Hindi English/Hindi Outline of Point-to-Point Communication 1. Signals basic
More informationThe quality of the transmission signal The characteristics of the transmission medium. Some type of transmission medium is required for transmission:
Data Transmission The successful transmission of data depends upon two factors: The quality of the transmission signal The characteristics of the transmission medium Some type of transmission medium is
More informationChapter 2. Physical Layer
Chapter 2 Physical Layer Lecture 1 Outline 2.1 Analog and Digital 2.2 Transmission Media 2.3 Digital Modulation and Multiplexing 2.4 Transmission Impairment 2.5 Data-rate Limits 2.6 Performance Physical
More informationUNIT I FUNDAMENTALS OF ANALOG COMMUNICATION Introduction In the Microbroadcasting services, a reliable radio communication system is of vital importance. The swiftly moving operations of modern communities
More informationCOMMUNICATION SYSTEMS -I
COMMUNICATION SYSTEMS -I Communication : It is the act of transmission of information. ELEMENTS OF A COMMUNICATION SYSTEM TRANSMITTER MEDIUM/CHANNEL: The physical medium that connects transmitter to receiver
More informationCollege of information Technology Department of Information Networks Telecommunication & Networking I Chapter DATA AND SIGNALS 1 من 42
3.1 DATA AND SIGNALS 1 من 42 Communication at application, transport, network, or data- link is logical; communication at the physical layer is physical. we have shown only ; host- to- router, router-to-
More informationData Transmission. ITS323: Introduction to Data Communications. Sirindhorn International Institute of Technology Thammasat University ITS323
ITS323: Introduction to Data Communications Sirindhorn International Institute of Technology Thammasat University Prepared by Steven Gordon on 23 May 2012 ITS323Y12S1L03, Steve/Courses/2012/s1/its323/lectures/transmission.tex,
More informationTE 302 DISCRETE SIGNALS AND SYSTEMS. Chapter 1: INTRODUCTION
TE 302 DISCRETE SIGNALS AND SYSTEMS Study on the behavior and processing of information bearing functions as they are currently used in human communication and the systems involved. Chapter 1: INTRODUCTION
More informationPart II Data Communications
Part II Data Communications Chapter 3 Data Transmission Concept & Terminology Signal : Time Domain & Frequency Domain Concepts Signal & Data Analog and Digital Data Transmission Transmission Impairments
More informationWIRELESS COMMUNICATION TECHNOLOGIES (16:332:546) LECTURE 5 SMALL SCALE FADING
WIRELESS COMMUNICATION TECHNOLOGIES (16:332:546) LECTURE 5 SMALL SCALE FADING Instructor: Dr. Narayan Mandayam Slides: SabarishVivek Sarathy A QUICK RECAP Why is there poor signal reception in urban clutters?
More informationEC 554 Data Communications
EC 554 Data Communications Mohamed Khedr http://webmail. webmail.aast.edu/~khedraast.edu/~khedr Syllabus Tentatively Week 1 Week 2 Week 3 Week 4 Week 5 Week 6 Week 7 Week 8 Week 9 Week 10 Week 11 Week
More informationOverview. Lecture 3. Terminology. Terminology. Background. Background. Transmission basics. Transmission basics. Two signal types
Lecture 3 Transmission basics Chapter 3, pages 75-96 Dave Novak School of Business University of Vermont Overview Transmission basics Terminology Signal Channel Electromagnetic spectrum Two signal types
More informationData and Computer Communications Chapter 3 Data Transmission
Data and Computer Communications Chapter 3 Data Transmission Eighth Edition by William Stallings Transmission Terminology data transmission occurs between a transmitter & receiver via some medium guided
More informationLecture 3: Data Transmission
Lecture 3: Data Transmission 1 st semester 1439-2017 1 By: Elham Sunbu OUTLINE Data Transmission DATA RATE LIMITS Transmission Impairments Examples DATA TRANSMISSION The successful transmission of data
More informationData Communications & Computer Networks
Data Communications & Computer Networks Chapter 3 Data Transmission Fall 2008 Agenda Terminology and basic concepts Analog and Digital Data Transmission Transmission impairments Channel capacity Home Exercises
More informationAnnouncement : Wireless Networks Lecture 3: Physical Layer. A Reminder about Prerequisites. Outline. Page 1
Announcement 18-759: Wireless Networks Lecture 3: Physical Layer Peter Steenkiste Departments of Computer Science and Electrical and Computer Engineering Spring Semester 2010 http://www.cs.cmu.edu/~prs/wirelesss10/
More informationReview of Lecture 2. Data and Signals - Theoretical Concepts. Review of Lecture 2. Review of Lecture 2. Review of Lecture 2. Review of Lecture 2
Data and Signals - Theoretical Concepts! What are the major functions of the network access layer? Reference: Chapter 3 - Stallings Chapter 3 - Forouzan Study Guide 3 1 2! What are the major functions
More informationUNIT-2 Angle Modulation System
UNIT-2 Angle Modulation System Introduction There are three parameters of a carrier that may carry information: Amplitude Frequency Phase Frequency Modulation Power in an FM signal does not vary with modulation
More informationSpeech, music, images, and video are examples of analog signals. Each of these signals is characterized by its bandwidth, dynamic range, and the
Speech, music, images, and video are examples of analog signals. Each of these signals is characterized by its bandwidth, dynamic range, and the nature of the signal. For instance, in the case of audio
More informationChapter 3 Data and Signals
Chapter 3 Data and Signals 3.2 To be transmitted, data must be transformed to electromagnetic signals. 3-1 ANALOG AND DIGITAL Data can be analog or digital. The term analog data refers to information that
More informationCOMP211 Physical Layer
COMP211 Physical Layer Data and Computer Communications 7th edition William Stallings Prentice Hall 2004 Computer Networks 5th edition Andrew S.Tanenbaum, David J.Wetherall Pearson 2011 Material adapted
More informationINTRODUCTION TO COMMUNICATION SYSTEMS AND TRANSMISSION MEDIA
COMM.ENG INTRODUCTION TO COMMUNICATION SYSTEMS AND TRANSMISSION MEDIA 9/9/2017 LECTURES 1 Objectives To give a background on Communication system components and channels (media) A distinction between analogue
More informationChapter 3 Data and Signals 3.1
Chapter 3 Data and Signals 3.1 Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Note To be transmitted, data must be transformed to electromagnetic signals. 3.2
More informationLecture 6. Angle Modulation and Demodulation
Lecture 6 and Demodulation Agenda Introduction to and Demodulation Frequency and Phase Modulation Angle Demodulation FM Applications Introduction The other two parameters (frequency and phase) of the carrier
More informationElectronics Interview Questions
Electronics Interview Questions 1. What is Electronic? The study and use of electrical devices that operate by controlling the flow of electrons or other electrically charged particles. 2. What is communication?
More information2. TELECOMMUNICATIONS BASICS
2. TELECOMMUNICATIONS BASICS The purpose of any telecommunications system is to transfer information from the sender to the receiver by a means of a communication channel. The information is carried by
More informationElements of Communication System Channel Fig: 1: Block Diagram of Communication System Terminology in Communication System
Content:- Fundamentals of Communication Engineering : Elements of a Communication System, Need of modulation, electromagnetic spectrum and typical applications, Unit V (Communication terminologies in communication
More informationCOMMUNICATION SYSTEMS NCERT
Exemplar Problems Physics Chapter Fifteen COMMUNCATON SYSTEMS MCQ 151 Three waves A, B and C of frequencies 1600 khz, 5 MHz and 60 MHz, respectively are to be transmitted from one place to another Which
More informationCourse 2: Channels 1 1
Course 2: Channels 1 1 "You see, wire telegraph is a kind of a very, very long cat. You pull his tail in New York and his head is meowing in Los Angeles. Do you understand this? And radio operates exactly
More informationPhysical Layer. Networks: Physical Layer 1
Physical Layer Networks: Physical Layer 1 Physical Layer Part 1 Definitions Nyquist Theorem - noiseless Shannon s Result with noise Analog versus Digital Amplifier versus Repeater Networks: Physical Layer
More informationE-716-A Mobile Communications Systems. Lecture #2 Basic Concepts of Wireless Transmission (p1) Instructor: Dr. Ahmad El-Banna
October 2014 Ahmad El-Banna Integrated Technical Education Cluster At AlAmeeria E-716-A Mobile Communications Systems Lecture #2 Basic Concepts of Wireless Transmission (p1) Instructor: Dr. Ahmad El-Banna
More informationData Communications and Networks
Data Communications and Networks Abdul-Rahman Mahmood http://alphapeeler.sourceforge.net http://pk.linkedin.com/in/armahmood abdulmahmood-sss twitter.com/alphapeeler alphapeeler.sourceforge.net/pubkeys/pkey.htm
More informationChapter 2 Channel Equalization
Chapter 2 Channel Equalization 2.1 Introduction In wireless communication systems signal experiences distortion due to fading [17]. As signal propagates, it follows multiple paths between transmitter and
More informationUNIT-1. Basic signal processing operations in digital communication
UNIT-1 Lecture-1 Basic signal processing operations in digital communication The three basic elements of every communication systems are Transmitter, Receiver and Channel. The Overall purpose of this system
More informationCSCD 433 Network Programming Fall Lecture 5 Physical Layer Continued
CSCD 433 Network Programming Fall 2016 Lecture 5 Physical Layer Continued 1 Topics Definitions Analog Transmission of Digital Data Digital Transmission of Analog Data Multiplexing 2 Different Types of
More informationFundamentals of Digital Communication
Fundamentals of Digital Communication Network Infrastructures A.A. 2017/18 Digital communication system Analog Digital Input Signal Analog/ Digital Low Pass Filter Sampler Quantizer Source Encoder Channel
More informationData Transmission (II)
Agenda Lecture (02) Data Transmission (II) Analog and digital signals Analog and Digital transmission Transmission impairments Channel capacity Shannon formulas Dr. Ahmed ElShafee 1 Dr. Ahmed ElShafee,
More informationtwo computers. 2- Providing a channel between them for transmitting and receiving the signals through it.
1. Introduction: Communication is the process of transmitting the messages that carrying information, where the two computers can be communicated with each other if the two conditions are available: 1-
More informationPRINCIPLES OF COMMUNICATION SYSTEMS. Lecture 1- Introduction Elements, Modulation, Demodulation, Frequency Spectrum
PRINCIPLES OF COMMUNICATION SYSTEMS Lecture 1- Introduction Elements, Modulation, Demodulation, Frequency Spectrum Topic covered Introduction to subject Elements of Communication system Modulation General
More informationComputer Networks. Practice Set I. Dr. Hussein Al-Bahadili
بسم االله الرحمن الرحيم Computer Networks Practice Set I Dr. Hussein Al-Bahadili (1/11) Q. Circle the right answer. 1. Before data can be transmitted, they must be transformed to. (a) Periodic signals
More informationStructure of Speech. Physical acoustics Time-domain representation Frequency domain representation Sound shaping
Structure of Speech Physical acoustics Time-domain representation Frequency domain representation Sound shaping Speech acoustics Source-Filter Theory Speech Source characteristics Speech Filter characteristics
More informationOutline. Communications Engineering 1
Outline Introduction Signal, random variable, random process and spectra Analog modulation Analog to digital conversion Digital transmission through baseband channels Signal space representation Optimal
More informationLecture 3 Concepts for the Data Communications and Computer Interconnection
Lecture 3 Concepts for the Data Communications and Computer Interconnection Aim: overview of existing methods and techniques Terms used: -Data entities conveying meaning (of information) -Signals data
More informationCPSC Network Programming. How do computers really communicate?
CPSC 360 - Network Programming Data Transmission Michele Weigle Department of Computer Science Clemson University mweigle@cs.clemson.edu February 11, 2005 http://www.cs.clemson.edu/~mweigle/courses/cpsc360
More informationSAMPLE. UEENEEH046B Solve fundamental problems in electronic communications systems. Learner Workbook. UEE07 Electrotechnology Training Package
UEE07 Electrotechnology Training Package UEENEEH046B Solve fundamental problems in electronic communications systems Learner Workbook Version 1 Training and Education Support Industry Skills Unit Meadowbank
More informationECE 476/ECE 501C/CS Wireless Communication Systems Winter Lecture 6: Fading
ECE 476/ECE 501C/CS 513 - Wireless Communication Systems Winter 2005 Lecture 6: Fading Last lecture: Large scale propagation properties of wireless systems - slowly varying properties that depend primarily
More informationProject = An Adventure : Wireless Networks. Lecture 4: More Physical Layer. What is an Antenna? Outline. Page 1
Project = An Adventure 18-759: Wireless Networks Checkpoint 2 Checkpoint 1 Lecture 4: More Physical Layer You are here Done! Peter Steenkiste Departments of Computer Science and Electrical and Computer
More informationDigital and Analog Communication (EE-217-F)
Digital and Analog Communication (EE-217-F) BOOK Text Book: Data Communications, Computer Networks and Open Systems Halsall Fred, (4thediton) 2000, Addison Wesley, Low Price edition Reference Books: Business
More informationChapter 3 Data Transmission COSC 3213 Summer 2003
Chapter 3 Data Transmission COSC 3213 Summer 2003 Courtesy of Prof. Amir Asif Definitions 1. Recall that the lowest layer in OSI is the physical layer. The physical layer deals with the transfer of raw
More informationChapter-1: Introduction
Chapter-1: Introduction The purpose of a Communication System is to transport an information bearing signal from a source to a user destination via a communication channel. MODEL OF A COMMUNICATION SYSTEM
More informationCSCD 433 Network Programming Fall Lecture 5 Physical Layer Continued
CSCD 433 Network Programming Fall 2016 Lecture 5 Physical Layer Continued 1 Topics Definitions Analog Transmission of Digital Data Digital Transmission of Analog Data Multiplexing 2 Different Types of
More informationUNIT I AMPLITUDE MODULATION
UNIT I AMPLITUDE MODULATION Prepared by: S.NANDHINI, Assistant Professor, Dept. of ECE, Sri Venkateswara College of Engineering, Sriperumbudur, Tamilnadu. CONTENTS Introduction to communication systems
More informationCommunication Engineering Prof. Surendra Prasad Department of Electrical Engineering Indian Institute of Technology, Delhi
Communication Engineering Prof. Surendra Prasad Department of Electrical Engineering Indian Institute of Technology, Delhi Lecture 1 Introduction to Communication Engineering I will go through a very brief
More informationUniversity Tunku Abdul Rahman LABORATORY REPORT 1
University Tunku Abdul Rahman FACULTY OF ENGINEERING AND GREEN TECHNOLOGY UGEA2523 COMMUNICATION SYSTEMS LABORATORY REPORT 1 Signal Transmission & Distortion Student Name Student ID 1. Low Hui Tyen 14AGB06230
More informationChapter 1 Introduction
Wireless Information Transmission System Lab. Chapter 1 Introduction National Sun Yat-sen University Table of Contents Elements of a Digital Communication System Communication Channels and Their Wire-line
More informationThe electric field for the wave sketched in Fig. 3-1 can be written as
ELECTROMAGNETIC WAVES Light consists of an electric field and a magnetic field that oscillate at very high rates, of the order of 10 14 Hz. These fields travel in wavelike fashion at very high speeds.
More informationLast Time. Transferring Information. Today (& Tomorrow (& Tmrw)) Application Layer Example Protocols ftp http Performance.
15-441 Lecture 5 Last Time Physical Layer & Link Layer Basics Copyright Seth Goldstein, 2008 Application Layer Example Protocols ftp http Performance Application Presentation Session Transport Network
More informationContents. Telecom Service Chae Y. Lee. Data Signal Transmission Transmission Impairments Channel Capacity
Data Transmission Contents Data Signal Transmission Transmission Impairments Channel Capacity 2 Data/Signal/Transmission Data: entities that convey meaning or information Signal: electric or electromagnetic
More informationCable Testing TELECOMMUNICATIONS AND NETWORKING
Cable Testing TELECOMMUNICATIONS AND NETWORKING Analog Signals 2 Digital Signals Square waves, like sine waves, are periodic. However, square wave graphs do not continuously vary with time. The wave holds
More informationECE 476/ECE 501C/CS Wireless Communication Systems Winter Lecture 6: Fading
ECE 476/ECE 501C/CS 513 - Wireless Communication Systems Winter 2004 Lecture 6: Fading Last lecture: Large scale propagation properties of wireless systems - slowly varying properties that depend primarily
More informationExperiment Five: The Noisy Channel Model
Experiment Five: The Noisy Channel Model Modified from original TIMS Manual experiment by Mr. Faisel Tubbal. Objectives 1) Study and understand the use of marco CHANNEL MODEL module to generate and add
More informationChapter 3 Data Transmission
Chapter 3 Data Transmission COSC 3213 Instructor: U.T. Nguyen 1 9/27/2007 3:21 PM Terminology (1) Transmitter Receiver Medium Guided medium e.g. twisted pair, optical fiber Unguided medium e.g. air, water,
More informationFourier Analysis. Chapter Introduction Distortion Harmonic Distortion
Chapter 5 Fourier Analysis 5.1 Introduction The theory, practice, and application of Fourier analysis are presented in the three major sections of this chapter. The theory includes a discussion of Fourier
More informationCharan Langton, Editor
Charan Langton, Editor SIGNAL PROCESSING & SIMULATION NEWSLETTER Baseband, Passband Signals and Amplitude Modulation The most salient feature of information signals is that they are generally low frequency.
More informationCommunications I (ELCN 306)
Communications I (ELCN 306) c Samy S. Soliman Electronics and Electrical Communications Engineering Department Cairo University, Egypt Email: samy.soliman@cu.edu.eg Website: http://scholar.cu.edu.eg/samysoliman
More informationELEC3242 Communications Engineering Laboratory Amplitude Modulation (AM)
ELEC3242 Communications Engineering Laboratory 1 ---- Amplitude Modulation (AM) 1. Objectives 1.1 Through this the laboratory experiment, you will investigate demodulation of an amplitude modulated (AM)
More informationAM Limitations. Amplitude Modulation II. DSB-SC Modulation. AM Modifications
Lecture 6: Amplitude Modulation II EE 3770: Communication Systems AM Limitations AM Limitations DSB-SC Modulation SSB Modulation VSB Modulation Lecture 6 Amplitude Modulation II Amplitude modulation is
More informationIntroduction to LAN/WAN. Physical Layer
Introduction to LAN/WAN Physical Layer Topics Introduction Theory Transmission Media Purpose of Physical Layer Transport bits between machines How do we send 0's and 1's across a medium? Ans: vary physical
More informationLab course Analog Part of a State-of-the-Art Mobile Radio Receiver
Communication Technology Laboratory Wireless Communications Group Prof. Dr. A. Wittneben ETH Zurich, ETF, Sternwartstrasse 7, 8092 Zurich Tel 41 44 632 36 11 Fax 41 44 632 12 09 Lab course Analog Part
More informationApplication of Fourier Transform in Signal Processing
1 Application of Fourier Transform in Signal Processing Lina Sun,Derong You,Daoyun Qi Information Engineering College, Yantai University of Technology, Shandong, China Abstract: Fourier transform is a
More informationAntennas and Propagation
Antennas and Propagation Chapter 5 Introduction An antenna is an electrical conductor or system of conductors Transmission - radiates electromagnetic energy into space Reception - collects electromagnetic
More informationAmplitude Modulation, II
Amplitude Modulation, II Single sideband modulation (SSB) Vestigial sideband modulation (VSB) VSB spectrum Modulator and demodulator NTSC TV signsals Quadrature modulation Spectral efficiency Modulator
More informationAmplitude Modulation II
Lecture 6: Amplitude Modulation II EE 3770: Communication Systems Lecture 6 Amplitude Modulation II AM Limitations DSB-SC Modulation SSB Modulation VSB Modulation Multiplexing Mojtaba Vaezi 6-1 Contents
More informationECE 476/ECE 501C/CS Wireless Communication Systems Winter Lecture 6: Fading
ECE 476/ECE 501C/CS 513 - Wireless Communication Systems Winter 2003 Lecture 6: Fading Last lecture: Large scale propagation properties of wireless systems - slowly varying properties that depend primarily
More informationChapter 3 Digital Transmission Fundamentals
Chapter 3 Digital Transmission Fundamentals Digital Representation of Information Why Digital Communications? Digital Representation of Analog Signals Characterization of Communication Channels Fundamental
More informationDATA TRANSMISSION. ermtiong. ermtiong
DATA TRANSMISSION Analog Transmission Analog signal transmitted without regard to content May be analog or digital data Attenuated over distance Use amplifiers to boost signal Also amplifies noise DATA
More informationEE 442 Homework #3 Solutions (Spring 2016 Due February 13, 2017 ) Print out homework and do work on the printed pages.
NAME Solutions EE 44 Homework #3 Solutions (Spring 06 Due February 3, 07 ) Print out homework and do work on the printed pages. Textbook: B. P. Lathi & Zhi Ding, Modern Digital and Analog Communication
More information14. COMMUNICATION SYSTEM
14. COMMUNICATION SYSTEM SYNOPSIS : INTRODUCTION 1. The exchange of information between a sender and receiver is called communication. 2. The arrangement of devices to transfere the information is called
More informationChannel Characteristics and Impairments
ELEX 3525 : Data Communications 2013 Winter Session Channel Characteristics and Impairments is lecture describes some of the most common channel characteristics and impairments. A er this lecture you should
More informationCHAPTER 2! AMPLITUDE MODULATION (AM)
CHAPTER 2 AMPLITUDE MODULATION (AM) Topics 2-1 : AM Concepts 2-2 : Modulation Index and Percentage of Modulation 2-3 : Sidebands and the Frequency Domain 2-4 : Single-Sideband Modulation 2-5 : AM Power
More informationPulse-Width Modulation (PWM)
Pulse-Width Modulation (PWM) Modules: Integrate & Dump, Digital Utilities, Wideband True RMS Meter, Tuneable LPF, Audio Oscillator, Multiplier, Utilities, Noise Generator, Speech, Headphones. 0 Pre-Laboratory
More information