Glossary

22 kHz   A control signal used for DiSEqC or for switching frequency bands.
     
Bandwidth   The frequency width of the transmitted information channel. The wider the bandwidth of a channel, the more information can be transmitted.
     

BER

  Bit Error Rate.
     
Broadcast data stream   A single stream that is meant to be received by all users. An example might be a newscast that anyone can watch.
     
Carrier frequency spacing   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.
     
CAT   Conditional Access Table. Information pertaining to subscriber access which is transmitted along with TV programs and the other digital information.
     
Channel frequency   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.
     
Demodulation   The process of recovering digital information from received radiation symbols.
     
DiSEqC   Digital Satellite Equipment Control. A single device which connects one or more digital receivers to one or more dish antennas.
     
Dish   A satellite antenna or the concave body of the satellite antenna.
     
DVB   Digital Video Broadcasting. A set of European standards for sending and receiving digital information which have been widely adopted around the world.
     
ECM   Entitlement Control Messages. Information pertaining to subscriber access which is transmitted along with TV programs and the other digital information.
     
EMM   Entitlement Management Messages. Information pertaining to subscriber access which is transmitted along with TV programs and the other digital information.
     
FEC   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.
     
Guard interval   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.
     
LNB   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.
     
Local oscillator   A component inside the LNB responsible for shifting the frequency of the received signal to the intermediate frequency band.
     
LOF   Local Oscillator Frequency. The frequency of the local oscillator.
     
MAC address   Media Access Control address. A numerical code used to address information that is meant for a particular user or users.
     
Modulation   The process of converting digital information into electromagnetic radiation symbols. There are many different types of modulation.
     
Multicast   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.
     
NIT   Network Information Table. An information table which is transmitted along with TV programs and the other digital information.
     
PAT   Program Association Table. An information table which is transmitted along with TV programs and the other digital information.
     
PCR   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.
     
PID   Program Identifier. A numerical code identifying a particular stream of information.
     
PMT   Program Map Table. An information table which is transmitted along with TV programs and the other digital information.
     
Polarity   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.
     
Proxy server   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.
     
QPSK   Quadrature Phase Shift Keying. A type of modulation used in satellite broadcasting.
     
QAM   Quaternary Amplitude Modulation. A type of modulation used in cable broadcasting.
     
Scan   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.
     
Symbol   Radiation that has been modified to represent digital information.
     
Symbol rate   Symbol rate is an indication of the speed at which the signal is transmitted.
     
Switch frequency   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.
     
Tuner   The part of the digital receiver which allows the receiver to tune into the selected channel.
     
Unicast   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.

 

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