22 kHz |
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A control signal used for DiSEqC or for
switching frequency bands. |
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Bandwidth |
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The frequency width of the transmitted information
channel. The wider the bandwidth of a channel, the more information can
be transmitted. |
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BER
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Bit Error Rate. |
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Broadcast data
stream |
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A single stream that is meant to be received
by all users. An example might be a newscast that anyone can watch. |
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Carrier frequency
spacing |
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In terrestrial broadcasting, the original
channel frequency carrying the selected information is split into multiple
carriers, typically more than a thousand different carrier frequencies,
each carrying small parts of the original channel's information. These
carriers have a precisely chosen frequency spacing between each carrier
known as the carrier frequency spacing. |
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CAT |
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Conditional Access Table. Information pertaining
to subscriber access which is transmitted along with TV programs and the
other digital information. |
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Channel frequency |
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Every channel broadcasts its own channel
of digital TV, radio, or Internet/data. Similar in principle to FM radio
stations, each channel is broadcast at its own channel frequency, also
called the channel frequency. |
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Demodulation
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The process of recovering digital information
from received radiation symbols. |
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DiSEqC |
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Digital Satellite Equipment Control. A single
device which connects one or more digital receivers to one or more dish
antennas. |
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Dish |
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A satellite antenna or the concave body
of the satellite antenna. |
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DVB |
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Digital Video Broadcasting. A set of European
standards for sending and receiving digital information which have been
widely adopted around the world. |
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ECM |
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Entitlement Control Messages. Information
pertaining to subscriber access which is transmitted along with TV programs
and the other digital information. |
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EMM |
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Entitlement Management Messages. Information
pertaining to subscriber access which is transmitted along with TV programs
and the other digital information. |
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FEC |
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FEC (Forward Error Correction) is a fractional
indicator of how much error correction code has been added to the original
digital code being transmitted. For example, if FEC is 7/8, then 7/8ths
of the transmitted signal is the original code, and 1/8th is error code
that has been added. Different channels may transmit with different amounts
of error correction code embedded in the signal. |
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Guard interval |
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In terrestrial broadcasting, multiple carriers
transmit the ones and zeroes of the digital signal as radiation called
modulation symbols. Each symbol is transmitted as an active symbol transmission
period followed by a short interval of rest time called the guard interval. |
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LNB |
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Low Noise Block converter. The device in
an antenna which points at the satellite. The LNB amplifies the received
signal and converts it to an intermediate frequency. |
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Local oscillator |
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A component inside the LNB responsible for
shifting the frequency of the received signal to the intermediate frequency
band. |
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LOF |
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Local Oscillator Frequency. The frequency
of the local oscillator. |
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MAC address |
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Media Access Control address. A numerical
code used to address information that is meant for a particular user or
users. |
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Modulation |
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The process of converting digital information
into electromagnetic radiation symbols. There are many different types
of modulation. |
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Multicast |
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A single stream that is mean to be received
by a select group of users identified by MAC address. An example might
be the live birth of a baby, being multicast over the Internet to the
parent's relatives around the world. |
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NIT |
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Network Information Table. An information
table which is transmitted along with TV programs and the other digital
information. |
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PAT |
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Program Association Table. An information
table which is transmitted along with TV programs and the other digital
information. |
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PCR |
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Program Clock Reference. Information which
is transmitted along with TV programs and the other digital information.
Information used to synchronize the receiver system time clock with the
transmitter system time clock. |
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PID |
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Program Identifier. A numerical code identifying
a particular stream of information. |
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PMT |
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Program Map Table. An information table
which is transmitted along with TV programs and the other digital information. |
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Polarity |
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The actual satellite signal is transmitted
as a radio wave. Waves possess a characteristic called polarity, which
in this case may be either horizontal or vertical. Horizontal is also
called Left. Vertical is also called Right. |
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Proxy server |
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A proxy server is a another computer that
acts as an intermediary between a user’s computer and the Internet/data
channel to be transmitted. Each channel has one or more proxy servers.
Each proxy server has its own IP address. In addition, your digital receiver
may have its own proxy server which communicates with these other proxies. |
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QPSK |
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Quadrature Phase Shift Keying. A type of
modulation used in satellite broadcasting. |
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QAM |
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Quaternary Amplitude Modulation. A type
of modulation used in cable broadcasting. |
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Scan |
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A process that adds TV and radio programs
to TV4PC's Program Guide (list of programs) by tuning into channels and
reading programming information tables in the received data. |
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Symbol |
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Radiation that has been modified to represent
digital information. |
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Symbol rate |
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Symbol rate is an indication of the speed
at which the signal is transmitted. |
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Switch frequency |
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The frequency at which the antenna switches
from using one local oscillator to using the other while trying to receive
a channel transmitted in a different frequency band. |
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Tuner |
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The part of the digital receiver which allows
the receiver to tune into the selected channel. |
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Unicast |
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A single stream that is meant to be received
only by the user (receiver) who requested the information. The user is
identified by MAC address. |