AX Quad Box HD 2400, User Manual

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FEC
Stand of or Forward Error Correction. This is a system of error control for data
transmission, whereby the sender adds redundant data to its messages, also
know as an error-correction code. This allows the receiver to detect and correct
errors (within some bound) without the need to ask the sender for additional
data. The advantages of forward error correction are that a back-channel is not
required and retransmission of data can often be avoided (at the cost of higher
bandwidth requirements, on average).
LNB
Stands for Low-Noise Block converter. This is the (receiving, or downlink) antenna
of what is commonly called the parabolic satellite dish commonly used for satellite
TV reception. The LNB is usually fixed on or in the satellite dish. The purpose of
the LNB is to take a wide block (or band) of relatively high frequency, amplify and
convert them to similar signal carried at a much lower frequency (called interme-
diate frequency or IF). These lower frequencies travel through cables with much
less attenuation of the signal, so there is much more signal left on the satellite
receiver end of the cable. It is also much easier and cheaper to design electronic
circuits to operate at these lower frequencies, rather than the very high frequen -
cies of satellite transmission.
PID
Stands for Packet Identifier. This is a set of numbers identifying stream packets
contained within a single data stream
Polarization
The orientation of the electrical and magnetic fields of a signal. Satellites use
mainly vertical and horizontal polarization.
S/PDIF
Stands for Sony / Philips Digital Interconnect Format. A common use for the S/PDIF
interface is to carry compressed digital audio as defined by the standard IEC
61937. This mode is used to connect the output of a DVD player to a home theater
receiver that supports Dolby Digital or DTS surround sound. Another common
use is to carry uncompressed digital audio from CD player to a receiver. This
specification also allows for the coupling of personal computer digital sound (if
equipped) via optical or coax to Dolby Digital or DTS capable receivers.
Smartcard
A Pocket-sized card with embedded Integrated Circuits which can process data.
It can receive input which is processed and delivered as an output. The card may
embed a hologram to avoid counterfeiting. It is used for accessing encrypted TV
channels or services.
Teletext
A television information retrieval service developed in the United Kingdom in
the early 1970s. It offers a range of text-based information, typically including
national, international and sporting news, weather and TV schedules. Subtitle (or
closed captioning) information is also transmitted in the teletext signal, typically
on page 888 or 777.