Chapter 1: Communication's Principles Flashcards
S P R of info by electrical or electronic means
Communications System
Alessandro Volta - electric battery
1799
Joseph Henry - transmitted first practical signal over one mile of wire to activate electromagnet
1830
Samuel Morse - invented telegraph
1837
Alexander Bain - Facsimile
1843
Transatlantic cable laid and failed
1858
Emile Baudot - binary code for telegraph
1875
Alexander Graham Bell patented the telephone.
1876
Thomas Alva Edison invented the phonograph.
1877
James Clerk Maxwell predicted mathematically radio propagation.
1864
Alexander Graham Bell patented the photophone.
1880
Heinrich Hertz verified experimentally Maxwell’s theory.
1887
Friedrich Reinitzer invented liquid crystal.
1888
Guglielmo Marco demonstrated wireless transmission.
1895
Reginald Fessenden invents AM
1906
Radio Station KDKA broadcasts the first regular licensed AM radio transmission.
1920
Philo Farnsworth produced the first all-electronic television transmission.
1927
Heinrich Lamm was the first to transmit images through a single glass fiber.
1930
Major Edwin Armstrong invented FM (frequency modulation) radio.
1933
Alec Reeves invented binary coded pulse-code modulation.
1937
First use of two-way radio (walkie-talkies).
1939
Invention and perfection of radar (World War II).
1940
The AT&T (American Telephone and Telegraph Company) inaugurated the first mobile telephone system for the public known as Mobile Telephone System.
1946
AT&T developed the concept of cellular telephony but the technology to realize the concept did not yet exist.
1947
Abraham van Heel, Harold Hopkins and Narinder Kapany announced imaging bundles, which propelled the fiber optics revolution and led to the development of flexible fiberscope.
1954
Russia launched the world’s first artificial satellite, Sputnik 1.
1957
Citizens band radio first used.
1961
NASA launches its first artificial satellite Telstar.
1962
HDTV (high-definition television) was introduced in Japan.
1970
Bob Kahn and Vint Cerf invented TCP (transmission control protocol).
1972
Robert Metcalfe invents Ethernet to wire local computers together, and Martin Cooper of Motorola invented the first practical mobile phone.
1973
First commercial use of optical fiber cables.
1977
Internet development and first use.
1982
AT&T opened the first commercial cellular telephone system in the United States.
1983
Tim Burners-Lee invents the WWW (World Wide Web).
1991
First browser Mosaic.
1993
Global Positioning System deployed.
1995
First smartphones by BlackBerry, Nokia, and Palm.
1996
First WLANS (wireless local area networks).
1997
DTV (digital television) transmission begins in the United States.
1999
First fourth-generation LTE (long-term evolution) cellular networks and first 100 Gbps fiber optical networks.
2009
Source of information. Performs encoding and modulation
Transmitter
M - modulation the signal
A - provides power to signal
O - provides carrier signal
Modulator, amplifier, oscillator
Destination of information. Performs decoding and demodulation
Receiver
D - Demodulates signal
A - provides power
O - devices such as speaker, monitor, etc.
Demodulator (detector), amplifier, output devices
Path or medium, which info travels unto. Attenuation (power loss) happens here
Transmission channels or medium
Electronic circuit for increasing signal magnitude or amplitude w/o altering signal
Amplifier
Produces periodic waveform with DC supply voltage as input. Non-rotating device to produce AC. Can be thought of as an ampli that provides itself (feedback)
Oscillator
Parallel resonant circuit. Used at high frequency.
LC oscillator
Note: RC oscillators are simpler, have lower cost, and are more suited for digital logic applications. LC oscillators are primarily used for higher-frequency applications, offer greater stability, and produce cleaner, nearly sinusoidal waveforms with fewer harmonics. They are commonly used in RF applications.
H oscillator - tapped coil as feedback
Co oscillator - split capacitor
Cl oscillator - addtl capacitor in series
Ar oscillator- tickler or transformer coil
Hartley
Colpitts
Clapp
Armstrong
USES RC networks for regenative feedback. Used for low frequencies
RC oscillator
*Note: The impedance of an RC filter approaches R as the frequency enters the pass band.The impedance of an LC filter approaches 0. So an RC filter will always be an attenuator while the ideal LC filter is not.
W B - oscillator- a sinusoidal feedback uses lead-lag circuit
P S- series of RC sections
Cr - output are highly stable and very precise frequency
Wien Bridge oscillator
Phase shift oscillator
Crystal oscillator
● Frequency selective circuit. Passes or rejects frequency.
● Simple filters constructed by RC or LC are?
● Special filters that uses RC w/ feedback opamp circuit… can use DSP
Filters, passive filters, active filters
Types of filter circuits:
LP - passes frequency below cutoff or critical frequency and attenuate above cutoff
HP- passes above but rejects below cutoff frequency
BP - passes frequency over narrow range between lower and upper cutoff
BR - rejects frequency over narrow range but allows frequency above and below to pass
AP - passes all equally but has phase shift characteristics
Low pass, high-pass, bandpass, band reject, All-pass
●Number of times a phenomenon occurs in a period of time.
●1 positive alteration and 1 negative alteration = ?
Frequency (Hz), 1 cycle
defined as a single-valued function of time that conveys information
Signal
time-varying voltages or currents that are continuously changing such as sine and cosine waves. Electrical signals of which amplitude changes continuously with respect to time with no breaks or discontinuities. Voice and video voltages
Analog signals
voltages or currents that change in discrete steps or levels. Electrical signals amplitude maintains constant level for a prescribed period of time and then it changes to another level with respect to time with no breaks or discontinuities. Most digital signals use binary
or two-state codes.
Digital signals
frequency range over which information signal is transmitted or over which a receiver or other circuits operates
Bandwidth
Known as cutoff, -3dB, breakup points
Half power points
Fundamental quantity for rate at which energy is used. Can be converted to heat
Power
Form of external noise when info signals from one source produce frequency that falls outside their allocated bandwidth and affects another source
Interference
●Most common type of noise.
●Can noise be fully eliminated?
●Noise can be reduced by?
Thermal noise, no only minimize, reducing bandwidth
●Used to determine the degree of intelligibility of a received signal
●Used to determine how much SN deteriorates as signal passes thru
●previous answer in dB
Signal to noise ratio, noise factor, noise figure
