ECE 407 Principles of Communication Systems PDF

ECE 407 Principles of Communication Systems Engr. Anthony V. Cruzat, ECE Guest Lecturer II Introduction to Electronic Communication Systems Learning Objectives Explain the functions of the three main parts of an electronic communication system. Describe the system used to classify different...

ECE 407 Principles of Communication Systems Engr. Anthony V. Cruzat, ECE Guest Lecturer II Introduction to Electronic Communication Systems Learning Objectives Explain the functions of the three main parts of an electronic communication system. Describe the system used to classify different types of electronic communication Discuss the role of modulation and multiplexing in facilitating signal transmission. Define the electromagnetic spectrum, its segments and their applications ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat  Significance of Human Communication ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat Significance of Human Communication Communication is the process of exchanging information. People communicate to convey their thoughts, ideas, and feelings to others. The process of communication is inherent to all human life and includes verbal, nonverbal (body language), print, and electronic processes. ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat Significance of Human Communication Two of the main barriers to human communication are language and distance. Language barriers arise between persons of different cultures or nationalities. Communicating over long distances is another problem. Communication between early human beings was limited to face-to-face encounters. ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat  Communication Systems ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat Communication Systems All electronic communication systems have a transmitter, a communication channel or medium, and a receiver. ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat Communication Systems In electronic communication systems, the message is referred to as information, or an intelligence signal. This message, in the form of an electronic signal, is fed to the transmitter, which then transmits the message over the communication channel. The message is picked up by the receiver and relayed to another human. Along the way, noise is added in the communication channel and in the receiver. ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat Communication Systems The transmitter itself is a collection of electronic components and circuits designed to convert the electrical signal to a signal suitable for transmission over a given communication medium. Transmitters are made up of oscillators, amplifiers, tuned circuits and filters, modulators, frequency mixers, frequency synthesizers, and other circuits. ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat Communication Systems The communication channel is the medium by which the electronic signal is sent from one place to another. Many different types of media are used in communication systems, including wire conductors, fiber-optic cable, and free space. ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat Communication Systems The communication channel is the medium by which the electronic signal is sent from one place to another. Many different types of media are used in communication systems, including wire conductors, fiber-optic cable, and free space. Free Space. When free space is the medium, the resulting system is known as radio. Also known as wireless, radio is the broad general term applied to any form of wireless communication from one point to another. Radio makes use of the electromagnetic spectrum. ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat Communication Systems A receiver is a collection of electronic components and circuits that accepts the transmitted message from the channel and converts it back to a form understandable by humans. Receivers contain amplifiers, oscillators, mixers, tuned circuits and filters, and a demodulator or detector that recovers the original intelligence signal from the modulated carrier. ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat Communication Systems Most electronic communication is two-way, and so both parties must have both a transmitter and a receiver. As a result, most communication equipment incorporates circuits that both send and receive. These units are commonly referred to as transceivers. All the transmitter and receiver circuits are packaged within a single housing and usually share some common circuits such as the power supply. ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat  Types of Electronic Communication System ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat Types of Electronic Communication Electronic communications are classified according to (1) mode of transmission and (2) type of signal. The different modes of transmission in an electronic communication are: simplex, half-duplex, and full- duplex. ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat Types of Electronic Communication The simplest way in which electronic communication is conducted is one-way communications, normally referred to as simplex communication. Example: PA broadcast system. The form of two-way communication in which only one party transmits at a time is known as half duplex communication. The communication is two-way, but the direction alternates: the communicating parties take turns transmitting and receiving. Example, two-way radio. ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat Types of Electronic Communication Transmissions can occur in both directions at the same time (two-way) is called full-duplex communication. ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat Types of Electronic Communication The different types of signal in an electronic communication are: analog and digital. An analog signal is a smoothly and continuously varying voltage or current. Voice and video voltages are analog signals that vary in accordance with the sound or light variations that are analogous to the information being transmitted ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat Types of Electronic Communication Digital signals, in contrast to analog signals, do not vary continuously, but change in steps or in discrete increments. Most digital signals use binary or two-state codes. ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat  Modulation and Multiplexing ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat Modulation and Multiplexing In a communication system, baseband information signals can be sent directly and unmodified over the medium or can be used to modulate a carrier for transmission over the medium. Putting the original voice, video, or digital signals directly into the medium is referred to as baseband transmission. ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat Modulation and Multiplexing In many instances, baseband signals are incompatible with the medium. As a result, the baseband information signal, be it audio, video, or data, is normally used to modulate a high-frequency signal called a carrier. The higher-frequency carriers radiate into space more efficiently than the baseband signals themselves. ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat Modulation and Multiplexing Modulation and multiplexing are electronic techniques for transmitting information efficiently from one place to another. Modulation makes the information signal more compatible with the medium, and multiplexing allows more than one signal to be transmitted concurrently over a single medium. ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat Modulation and Multiplexing Modulation is the process of having a baseband voice, video, or digital signal modify another, higher-frequency signal, the carrier. ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat Modulation and Multiplexing The intelligence signal changes the carrier in a unique way. The modulated carrier is amplified and sent to the antenna for transmission. This process is called broadband transmission. ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat Modulation and Multiplexing ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat Modulation and Multiplexing At the receiver, the carrier with the intelligence signal is amplified and then demodulated to extract the original baseband signal. Another name for the demodulation process is detection. ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat Modulation and Multiplexing Multiplexing is the process of allowing two or more signals to share the same medium or channel. A multiplexer converts the individual baseband signals to a composite signal that is used to modulate a carrier in the transmitter. Multiplexing is a method used by networks to consolidate multiple signals -- digital or analog -- into a single composite signal that is transported over a common medium, such as a fiber optic cable or radio wave. ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat Modulation and Multiplexing ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat Modulation and Multiplexing At the receiver, the composite signal is recovered at the demodulator, then sent to a demultiplexer where the individual baseband signals are regenerated ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat Modulation and Multiplexing Type of Multiplexing Frequency-division multiplexing (FDM) - the intelligence signals modulate subcarriers on different frequencies that are then added together, and the composite signal is used to modulate the carrier. Time-division multiplexing (TDM) - the multiple intelligence signals are sequentially sampled, and a small piece of each is used to modulate the carrier. ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat Modulation and Multiplexing Type of Multiplexing Code-division multiplexing - the signals to be transmitted are converted to digital data that is then uniquely coded with a faster binary code. The signals modulate a carrier on the same frequency. All use the same communications channel simultaneously. The unique coding is used at the receiver to select the desired signal. ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat Modulation and Multiplexing Type of Multiplexing Wavelength-division multiplexing - multiple communications channels are consolidated and then transmitted on light waves with different wavelengths. Space-division multiplexing - signal paths are spatially separated through the use of multiple conductors, such as optical fibers or electrical wires. ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat Modulation and Multiplexing ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat  Heat Check! A complete communication system must include: a. a transmitter and receiver b. a transmitter, a receiver, and a channel c. a transmitter, a receiver, and a spectrum analyzer d. a multiplexer, a demultiplexer, and a channel ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat  Heat Check! When two or more signals share a common channel, it is called a. sub-channeling b. signal switching c. SINAD d. multiplexing ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat  Heat Check! A transmission technique where each communication channel is allotted an epoch or time slot within a sampling frame, occupying essentially the entire wideband frequency spectrum for the allocated time. a. Time Division Multiplexing (TDM) b. Wavelength Division Multiplexing (WDM) c. Frequency Division Multiplexing (FDM) d. Statistical Time Division Multiplexing (STDM) ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat  Heat Check! Recovering information from a carrier is known as a. Modulation b. Detection c. Demultiplexing d. Carrier recovery ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat  The Electromagnetic Spectrum ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat The Electromagnetic Spectrum Electromagnetic waves are signals that oscillate; i.e., the amplitudes of the electric and magnetic fields vary at a specific rate. The field intensities fluctuate up and down, and the polarity reverses a given number of times per second. The electromagnetic waves vary sinusoidally. These oscillations may occur at a very low frequency or at an extremely high frequency. The range of electromagnetic signals encompassing all frequencies is referred to as the electromagnetic spectrum. ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat The Electromagnetic Spectrum ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat The Electromagnetic Spectrum ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat The Electromagnetic Spectrum ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat The Electromagnetic Spectrum Extremely Low Frequencies. ELFs are in the 30 to 300-Hz range. These include ac power line frequencies (50 and 60 Hz are common), as well as those frequencies in the low end of the human audio range. ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat The Electromagnetic Spectrum Voice Frequencies. VFs are in the range of 300 to 3000 Hz. This is the normal range of human speech. Although human hearing extends from approximately 20 to 20,000 Hz, most intelligible sound occurs in the VF range. ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat The Electromagnetic Spectrum Very Low Frequencies. VLFs extend from 9 kHz to 30 kHz and include the higher end of the human hearing range up to about 15 or 20 kHz. The VLF range is used in some government and military communication. ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat The Electromagnetic Spectrum Low Frequencies. LFs are in the 30- to 300-kHz range. The primary communication services using this range are in aeronautical and marine navigation. Frequencies in this range are also used as subcarriers, signals that are modulated by the baseband information. ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat The Electromagnetic Spectrum Medium Frequencies. MFs are in the 300- to 3000-kHz range. The major application of frequencies in this range is AM radio broadcasting (535 to 1605 kHz). Other applications in this range are various marine and amateur radio communication. ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat The Electromagnetic Spectrum High Frequencies. HFs are in the 3- to 30-MHz range. These are the frequencies generally known as short waves. All kinds of simplex broadcasting and half duplex two-way radio communication take place in this range. ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat The Electromagnetic Spectrum Very High Frequencies. VHFs encompass the 30 to 300 MHz range. This popular frequency range is used by many services, including mobile radio, marine and aeronautical communication, FM radio broadcasting (88 to 108 MHz), and television channels 2 through 13. ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat The Electromagnetic Spectrum Ultrahigh Frequencies. UHFs encompass the 300 to 3000 MHz range. It includes the UHF TV channels 14 through 51, and it is used for land mobile communication and services such as cellular telephones as well as for military communication. ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat The Electromagnetic Spectrum Microwave and Superhigh Frequencies. Frequencies between the 1000-MHz (1-GHz) and 30-GHz range are called microwaves. Microwave ovens usually operate at 2.45 GHz. Superhigh frequencies (SHFs) are in the 3- to 30-GHz range. ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat The Electromagnetic Spectrum Microwave and Superhigh Frequencies. These microwave frequencies are widely used for satellite communication and radar. Wireless local-area networks (LANs) and many cellular telephone systems also occupy this region. ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat The Electromagnetic Spectrum Extremely High Frequencies. EHFs extend from 30 to 300 GHz. Electromagnetic signals with frequencies higher than 30 GHz are referred to as millimeter waves. There is growing use of this range for satellite communication telephony, computer data, short-haul cellular networks. ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat The Electromagnetic Spectrum Right above the millimeter wave region is what is called the optical spectrum, the region occupied by light waves. There are three different types of light waves: infrared, visible, and ultraviolet. ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat The Electromagnetic Spectrum Infrared. Infrared occupies the range between approximately 0.1 millimeter (mm) and 700 nanometers (nm), or 100 to 0.7 micrometer (μm). Infrared is the basis for all fiber optic communication. ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat The Electromagnetic Spectrum Visible Light. Just above the infrared region is the visible spectrum we ordinarily refer to as light. Light is a special type of electromagnetic radiation that has a wavelength in the 0.4- to 0.8-μm range (400 to 800 nm). ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat The Electromagnetic Spectrum Visible Light. Light wavelengths are usually expressed in terms of angstroms (Å). An angstrom is one ten-thousandth of a micrometer. The visible range is approximately 8000 Å (red) to 4000 Å (violet). ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat The Electromagnetic Spectrum Ultraviolet. Ultraviolet light (UV) covers the range from about 4 to 400 nm. Ultraviolet generated by the sun is what causes sunburn. Ultraviolet is not used for communication; its primary use is medical. ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat The Electromagnetic Spectrum X-rays. Majority used in medical applications. Used in x- ray scans to see the inside of bodies or thing. Gamma rays. Highest energy, highest frequency, and shortest wavelength of any electromagnetic waves; can be used in medicine to kill cancer cells. ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat The Electromagnetic Spectrum Spectrum Management is the process of regulating the use of radio frequencies to promote efficient use and gain a net social benefit. A lack of regulation around the use of radio frequencies would clog up communication and prevent people from communicating. ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat  The Bandwidth ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat The Bandwidth Bandwidth (BW) are is that portion of the electromagnetic spectrum occupied by a signal. It is also the frequency range over which a receiver or other electronic circuit operates. More specifically, bandwidth is the difference between the upper and lower frequency limits of the signal or the equipment operation range. The bandwidth, then, is 𝑩𝑾 = 𝒇𝟐 − 𝒇𝟏 ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat The Bandwidth When information is modulated onto a carrier somewhere in the electromagnetic spectrum, the resulting signal occupies a small portion of the spectrum surrounding the carrier frequency. The modulation process causes other signals, called sidebands, to be generated at frequencies above and below the carrier frequency by an amount equal to the modulating frequency. ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat The Bandwidth In other words, the modulation process generates other signals that take up spectrum space. It is not just the carrier that is transmitted. Thus the term bandwidth refers to the range of frequencies that contain the information. The term channel bandwidth refers to the range of frequencies required to transmit the desired information. ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat  Heat Check! If the measured wavelength is 6 m, calculate the frequency in MHz a. 25 MHz b. 50 MHz c. 10 MHz d. 100 MHz ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat  Heat Check! Based on ITU-R Recommendations V.431-6, the adjectival designation of 30 to 300 kHz is a. ELF b. ULF c. VLF d. LF ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat  Heat Check! How many international commercial AM broadcast channels (assume BW=10 KHz) can fit into the bandwidth occupied by a commercial FM broadcast channel (assume BW=200 KHz)? a. 200 b. 5 c. 10 d. 20 ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat  “ Excellence is not a skill. It is an attitude. Ralph Marston ECE 407 - PCOMMS INTRODUCTION TO ELECTRONIC COMMUNICATION SYSTEMS Engr. A. V. Cruzat