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either rotate in a clock wise fashion or counter clockwise. Polarization is very useful
because it allows the frequency of a Right polarized signal to overlap with the same
frequencies of a Left polarized signal.
In layman's terms, a linearly polarized signal from a satellite approaches the
Polarization, Linear
(Horizontal/Vertical)
earth as a wave that goes up and down like the waves on the ocean, or from side to
side. These two types of waves are classified as being vertically or horizontally
polarized. Polarization is very useful because it allows the frequency of a vertically
polarized signal to overlap with the same frequencies of a Horizontally polarized
signal.
Random access memory. Used for short term storage of information requiring quick
RAM
access on a computer. Information stored in RAM can be accessed by the computer
much faster than information on the Hard Drive can be accessed.
Each satellite in orbit has several channels that it can use, each with its own RF
RF Frequency
Frequency. (Each channel is often referred to as a transponder.) The easiest way to
understand them is to think of your FM radio. There are many channels on the FM dial
that one can choose from. ("99.9 FM, All Rock, All the Time") When you input the
station number to your FM receiver you are actually telling it what RF Frequency it
should look at. (99.9 FM means that 99.9 Mega Hz is the desired frequency.) But
unlike the FM radio where the channel you tune to only contains one stream of music,
a satellite channel contains many individual signals. One channel can contain Internet
data and video and audio and specialized data in any number of permutations and
combinations. The S300 uses the PID numbers that come with each Internet data,
video, audio and specialized data signal to separate them all. (See PID.)
Satellite Signal Hierarchy
up to a theoretical maximum of 8190 packet streams identified by their individual PIDs.
A portion of a network, which may be a physically independent network segment, and
Subnet
which shares a network address with other portions of the network.
See Msps
Symbol Rate
This is the unit on the satellite that receives a signal transmitted from the earth station,
Transponder
amplifies it, changes its frequency and retransmits it back down to earth. Each radio
channel has its own transponder and a number of transponders on the satellite are
used to cover the allocated frequency band. A typical satellite will have 24
transponders.
"Convolutional encoding with Viterbi decoding is a Forward Error Correction technique
Viterbi
that is particularly suited to a channel in which the transmitted signal is corrupted
mainly by additive white Gaussian noise." Further information can be found by
searching the Internet or looking at any of these sites.
Version: 1.2
1 Satellite has -
10 - 24 Transponders (Channels) each with
dozens of distinct RF Frequencies each containing
http://pw1.netcom.com/~chip.f/Viterbi.html
http://hissa.nist.gov/dads/HTML/viterbiAlgorithm.html
Confidential and Proprietary
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