Principles of Communications Flashcards
it is the process of sending, processing and receiving information by electrical or electronic means
Communications System
it refers to the basic process of exchanging information by - electronic means
Communications System
1799 , Invented the electric Battery
Alessandro Volta
1830 , He transmitted the first practical electrical signal over one mile of wire to activate electromagnet
Joseph Henry
1837, He Invented the telegraph
Samuel Finley Breese Morse
1843, He Invented the Facsimile
Alexander Bain
1875, She designed a fixed-length binary code for telegraph
Emily Baudot
1876 , He patented the telephone
Alexander Graham Bell
1877 , He invented phonograph
Thomas Alva Edison
1864 , He predicted mathematically radio propagation.
James Clerk Maxwell
1880 , He patented the photophone
Alexander Graham Bell
1887, He verified experimentally Maxwell’s Theory
Heinrich Hertz
1888, He invented Liquid Crystal
Friedrich Reinitzer
1895, He demonstrated Wireless Transmission
Guglielmo Marconi
1906, He invents Amplitude Modulation (AM)
Reginald Fessenden
1920, Radio Station _____ Broadcasts the first regular licensed AM radio transmission
KDKA
1927, he produced the first all-electronic television transmission
Philo Farnsworth
1930, He was the first to transmit images through a single glass fiber
Heinrich Lamm
1933, He invented invented FM (Frequency Modulation) radio
Major Edwin Armstrong
1937 , He Invented binary coded pulse-code modulation
Alec Reeves
1946, They inaugurated the first mobile telephone system for the public known as mobile telephone system
AT & T ( American Telephone and Telegrap Company )
1947, they developed the concept of cellular telephony but the technology to realized the concept did not yet exist
AT & T
1954 , They announced imaging bundles, which propelled the fiber optics revolution and led to the development of flexible fiberscope
Abraham Van Heel, Harold Hopkins, Narinder Kapany
1957, Russia Launched the world’s first artificial satellite named
Sputnik I
1962, NASA launches its first artificial satellite named
Telstar
1970, HDTV(high-definition Tv) was introduced in
Japan
1972 , they invented the TCP ( Transmission Control Protocol )
Bob Kahn and Vint Cerf
1973, he invents Ethernet to wire local computers together
Robert Metacalfe
1973, He invented the first practical mobile phone
Martin Cooper of Motorola
1983, they opened the first commercial cellular telephone system in the United States
AT & T
1991, He invents the WWW (World Wide Web)
Tim Burners-Lee
1996, First Smartphones
BlackBerry, Nokia and Palm
It is the source of information, which must be delivered or transmitted to a particular destination over a channel.
It is a collection of one or more electronic devices or circuits that converts the original source information to a form more suitable for transmission
performs encoding and modulation
Transmitter
Three Basic Transmitter Components
Modulator (modulates the signal)
Amplifier (provides power to the signal)
Oscillator(provides the carrier signal)
it is the destination upon which information from the transmitter is delivered
it is a collection of electronic devices and circuits that accepts the transmitted signals from the transmission medium and then converts those signals back to their original form
performs decoding and demodulation
Receiver
Three Basic Receiver Components
Demodulator or Detector (demodulates the signal)
Amplifiers (it provides power to the signal)
Output Devices (such as speakers,monitor,printer etc).
it is the path or medium that the information travels from the transmitter to the receiver(i.e it provides a means of transporting signals between a transmitter and a receiver).
Attenuation ( sometimes referred to as power loss) occurs at this point.)
Transmission Medium or Transmission Channel
Two Classifications of Transmission Media
Guided Media ( Wired ) - in a form of conduit
-Trasmission lines (Twisted Pairs , Twin Lead , Open-Wire Lines, Coaxial Cables, etc.)
Unguided Media (Wireless) - radiated through air or vacuum
-Free Space
-Earth’s Atmosphere
it is an electronic circuit which is capable of increasing the signal magnitude or amplitude without appreciably altering the signal waveform characteristics.
Amplifier
active amplifier with a maximum efficiency of 25 or 50% and a conduction angle of 360 degrees and the distortion is Low
Class A Amplifier