Introduction to Electronic Communications Flashcards
Defined as the basic process of exchanging information
Communication
Two barriers in human communication
Language and Distance
When was the transmission of the first practical electrical signal?
1830
When was the telegraph invented?
1837
When was telephone invented?
1876
Who invented the telegraph?
Samuel Morse
Who transmitted the first practical electrical signal?
Joseph Henry
What did Samuel Morse invent?
Telegraph
Who invented the telephone?
Alexander Graham Bell and Thomas A. Watson
What did Alexander Graham Bell and Thomas A. Watson invent?
Telephone
When were radio waves discovered?
1887
Who discovered radio waves?
Heinrich Hertz
Heinrich Herts discovered what?
Radio Waves
When was the wireless radio wave propagation demonstrated?
1887
Who demonstrated wireless radio wave propagation?
Guglielmo Marconi
What did Guglielmo Marconi dis on 1887?
Demonstrated the wireless radio wave propagation.
When was the first transatlantic transmission of radio signals?
1901
Who accomplished the first transatlantic transmission of radio signals?
Guglielmo Marconi
What did Guglielmo Marconi accomplish in 1901?
First transatlantic transmission of radio signals.
When was the two-electrode vacuum-tube rectifier invented?
1903
Who invented the two-electrode vacuum-tube rectifier?
John Fleming
What did John Fleming invent?
Two-electrode vacuum-tube rectifier
When was the triode vacuum invented?
1906
Who invented the triode vacuum tube?
Lee De Forest
What did Lee De Forest invent?
Triode Vacuum Tube
When was the television invented and demonstrated?
1923
Who invented and demonstrated television?
Vladimir Zworykin
What did Vladimir Zworykin invented?
Television
When was the transistor invented??
1948
Who invented the transistor?
William Shockley, Walter Brattain, and John Bardeen
What did William Shockley, Walter Brittain, and John Bardeen invented?
Transistor
When was the integrated circuit invented?
1959
What happened in 1959?
The integrated circuit was invented.
When was the first commercial communications satellite launching?
1965
When was the first introduction of cellular telephone in US?
1983
What happened in 1965?
The first commercial satellite was launched
What happened in 1983?
The introduction of the cellular telephone in US.
Refers to the transmission, reception, and
processing of information using electronic circuits
Electronic Communications System
What are the basic elements of a communication system?
Transmitter, communications channel/medium, and receiver
Sources of information may be coming from an ______ source or from a _________ source
analog, digital
This signal continuously changes with respect to time and with infinite amplitude values
Analog signals
This signal is something discrete and whose amplitude is of finite value.
Digital Signal
A collection of electronic devices or circuits designed to convert the information into a signal suitable for transmission over a given communications medium
Transmitter
Provides the means of transporting signals
between a transmitter and a receiver
Communications Channel/Medium
It attenuates transmission of information and causes the received signal to appear much lower in amplitude
Communications channel or medium
A collection of electronic devices or circuits that accept the
transmitted message from the channel and convert them into a form
understandable to humans
Receivers
What are the two limitation of communication systems?
Noise & Bandwidth
Any unwanted form of energy that tends to interfere with the
proper and easy reception and reproduction of desired signals.
Noise
The portion of the electromagnetic spectrum occupied by a signal.
Bandwidth
The frequency range over which an information signal is
transmitted or over which a receiver or other electronic circuit operates
Bandwidth
The difference between the upper and the lower
frequency limit
Upper Limit Lower Limit
Bandwidth
A measure of how much source information can be carried through the system in a given period of time
Information Capacity
It states that the information capacity is directly proportional to bandwidth and transmission time
Hartley’s Law
One-way communication is called
simplex or broadcasting
Two-way communication is called
duplex
Only one of the parties can transmit at a time
half-duplex
Both partes may transmit and receive simultaneously
full-duplex
Examples of simplex
AM and FM Radio broadcasting, TV broadcasting, Cable Television, Wireless Remote Control, Paging Services, Navigation and Direction-Finding Services
Examples of Half-duplex
Two-way Radio, Amateur Radio, Citizens Radio, Radar, Sonar
Examples of full-duplex
Telephones, Data-Communications, Local Area Networks
Transmits and receives simultaneously but not necessarily between the same two locations.
Full/full Duplex
It is the entire range of usable frequencies
Electromagnetic Spectrum
Tt is the number of times an alternating current goes through its complete cycle per second
Frequency
Give 2 application of Extremely Low Frequencies
AC power line, end of human hearing range
Human hearing range
20 to 20000Hz
What do you call the normal range of the human voice?
Voice Frequencies (300 - 3000 Hz)
Very Low Frequencies application
Higher end of the human hearing range, musical instruments
Low Frequencies application
Aeronautical and marine navigation
Medium Frequencies Application
AM Radio Broadcasting, Marine and Aeronautical Communications
AM Radio Frequency Range
535 - 1605 kHz
Generally known as short waves
High Frequencies
High Frequencies Application
All kinds of two-way radio communication
Very High Frequencies Application
Mobile Radio, Marine and Aeronautical communications, FM radio broadcasting, and television channels 2-13
FM Radio Broadcasting Frequency range
88 - 108 MHz
Ultra High Frequencies Application
Television channels 14-83, land mobile communications, cellular telephones
Super High Frequencies Applications
Satellite and Radar Communications
Extremely High Frequencies Application
Satellite communications and some specialized radar
Infrared Applications
Detect stars, remote control units, guidance of weapon systems, and optical devices.
Visible Spectrum Applications
Communication Systems, fiber optics, and laser technology.
The length that one cycle of an electromagnetic wave occupies in space
Wavelength
What is the formula for wavelength
k(c/f)
Very short wavelengths are usually expressed as
Angstrom (1/10000) um
Equipment that represents the signal in the frequency domain is the
Spectrum Analyzer
A complete communication system should include
A transmitter, a receiver, and a channel
The bandwidth required for a modulated carrier depends on
the baseband frequency range
The baseband bandwidth for a voice-grade (telephone) signal is
approximately 3 kHz
A simultaneous two-way communication
full duplex
Recovering the originally transmitted signal is called
demodulation
Microwaves start at
Ultra High Frequencies
