This is the summary notes of the important terms and concepts in Chapter 26 of the book "Electronic Communications System" by Wayne Tomasi. The notes are properly synchronized and concise for much better understanding of the book. Make sure to familiarize this review notes to increase the chance of passing the ECE Board Exam.
Items
|
Definitions
|
Terms
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1
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Also called as Multiple Destination, It implies that more than
one user has access to one or more radio channels within a satellite
communications channel.
Multiple Accessing Arrangement:
·
Frequency-division
multiple accessing (FDMA)
·
Time-division
multiple accessing (TDMA)
·
Code-division
multiple accessing (CDMA)
|
Multiple Accessing
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2
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A given number of the available voice-band channels from each
earth station are assigned a dedicated destination.
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Pre-assignment (dedicated)
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3
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Voice channels are assigned on an as-needed basis.
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Demand Assignment
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4
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The method of assigning adjacent channels different
electromagnetic polarizations and is possible by using orthogonal
polarization and spacing adjacent channels 20 MHz apart.
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Frequency Reuse
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5
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Eskimo word meaning “little brother”.
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Anik
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6
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Domestic Satellites operated by Telsat Canada.
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Anik-E communications Satellite
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7
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A method of multiple accessing where a given RF bandwidth is
divided into smaller frequency bands.
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FDMA
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8
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Multiple channels per carrier formats assigned and remain
fixed for a long Period of time.
|
Fixed-Assignment, Multiple
Access (FAMA)
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9
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Assigning carrier frequency on temporary basis using a
statistical assignment process.
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Demand-Assignment
Multiple Access
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10
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An acronym for Single-channel-per-carrier PCM multiple Access
Demand-assignment Equipment.
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SPADE
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11
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Stands for Single-Carrier-Per-Channel.
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SCPC
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12
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A time division-multiplexed transmission that is frequency
division multiplexed.
|
Common Signaling Channel
(CSC)
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13
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The predominant Multiple-access method of time division
multiplexing digitally modulated carriers between participating earth
stations within a satellite network through a common satellite transponder.
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TDMA
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14
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An RF-to-RF repeater that simply receives the earth station
transmissions, amplifies them, and then retransmits them in a downlink beam
that is received by all other participating station.
|
Transponder
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15
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It is where transmissions from all earth stations are
synchronized.
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Reference Burst
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16
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It is where all receiving stations recover a frequency and
phase coherent carrier for PSK demodulation.
|
Carrier Recovery Sequence
(CRS)
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17
|
An acronym for, Conference of European Postal and
Telecommunications Administrations, is commonly used TDMA frame format for
digital satellite system.
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CEPT
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18
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Sometimes referred to as Spread-Spectrum Multiple entire
allocated bandwidth Access, the transmissions can spread throughout.
|
Code-Division Multiple Access
CDMA)
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19
|
A unique binary word that each earth station’s transmissions
are encoded.
|
Chip Code
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20
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It compares two signals and recover the original data.
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Correlator
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21
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It assigns an individual terrestrial channel (TC) to a
particular satellite channel (SC) for the duration of the call.
|
Digital non interpolated Interface
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22
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It assigns a terrestrial channel to a satellite channel only
when speech energy is present on the TC.
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Digital Speech Interpolated Interface
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23
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A form of analog channel compression that has been used for
sub oceanic cables for many years.
|
Time-Assignment Speech Interpolation
(TASI)
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24
|
The art or science of plotting, ascertaining or directing the
course of movements, in other words, knowing where you are and being able to
find your way around.
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Navigation
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25
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It is the most ancient and rudimentary method of navigation
and simply continuing to travel about until you reach your destination,
assuming of course that you have one.
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Wandering
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26
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Earliest effective means of navigation wherein direction and
distance are determined from precisely timed sightings of celestial bodies,
including the stars and moon.
|
Celestial Navigation
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27
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Method of navigation by means of fixing a position and
direction with respect to familiar, significant landmarks such as railroad
tracks, water towers, barns, mountains and bodies of water.
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Piloting
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28
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A navigation technique that determines position by
extrapolating a series of measured velocity increments.
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Dead Reckoning
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29
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The term derived from the word “deduced” and not necessarily
from the fate of the people who used the technique.
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Dead
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30
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He used dead reckoning successfully in 1927 during his
historic 33-hour transatlantic journey.
|
Charles Lindbergh
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31
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She attempted to make the first around-the-world in 1937 using
the dead reckoning technique.
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Amelia Earhart
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32
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Navigation technique wherein the position is determined by
measuring the travel time of an electromagnetic wave as it moves from a
transmitter to a receiver.
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Radio Navigation
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33
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A radio Navigation system for terrestrial surface broadcast.
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Decca
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34
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Radio Navigation system that provides global coverage and
terrestrial surface broadcast.
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Omega
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35
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Also a terrestrial surface broadcast.
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LORAN
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36
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Low-orbit satellite broadcast that provides global coverage.
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Navy Transit GPS
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37
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Medium-orbit satellite broadcast also provides global
coverage.
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Navstar GPS
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38
|
Means of radio navigation in which receivers acquire Coded
signals from two pairs of high-powered, land based transmitters whose
locations are precisely known.
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LORAN
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39
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An acronym for Navigation System with Time and Ranging.
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Navstar
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40
|
An abbreviation for Global Positioning System.
Two levels of service or accuracy:
·
Standard
Positioning Service
·
Precise
Positioning Service
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GPS
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41
|
A satellite-based open navigation system which simply means
that it is available to anyone equipped with a GPS receiver.
Consists of three segments:
·
a
space segment
·
a
ground control segment
·
user
segment
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Navstar GPS
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42
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It was when the Navstar declared as fully operational by the
U.S. Air Force Space Command.
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April 27, 1995
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43
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It was completed in 1994 and is maintained by the United
States Air Force.
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Navstar Satellite System
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44
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A positioning and timing service that is available to all GPS
users on a continuous, worldwide basis with no direct change.
|
Standard Positioning
Service
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45
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Sometimes called Space Segment, consists of 24operational
satellites revolving around Earth in six orbital planes approximately 60°
apart with four satellites in each plane.
|
Satellite Segment
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46
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It produces highly accurate timing signals for satellites.
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Cesium Atomic Clock
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47
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A unique integer number that is used to encrypt the signal
from that satellite.
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Pseudorandom Noise
(PRN)
Code Number
|
48
|
A term associated with a table showing the position of a
heavenly body on a number dates in a regular sequence, in essence, an
astronomical almanac.
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Ephemeris
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49
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Error in the receiver’s clock which affects the accuracy of
the time-difference measurement.
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Clock Bias Error
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50
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The Navstar control segment.
It consists of :
·
Fixed-location
ground based monitor stations
·
Master
Control Station
·
uplink
transmitter
|
Operational Control
System
|
51
|
It makes standard GPS more accurate. It works by cancelling
out most of the natural and man-made errors that creep into normal GPS
measurements.
|
Differential GPS
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