Glossary - XSAT CD.TV410 Manual

DVB MPEG-2
DVB is the abbreviation of Digital Video Broad-
casting, which is a standardisation group. DVB-S
corresponds to the type of transmission (S = Satel-
lite). MPEG is the abbreviation of Moving Picture
Experts Group, a working group which defines
international standards for audio and video digital
compression. The MPEG 2 standard applies to the
compression of digital TV signals.
DiSEqC
DiSEqC (Digital Satellite Equipment Control) is a
communication protocol defined by EUTELSAT,
between the satellite receiver (Master) and the
peripherals (Slaves), such as the LNBs, the multi-
switch and position-adjustable dishes. DiSEqC is a
"one master / several slaves" system, which
means that the installation only supports one mas-
ter. All the commands are sent by the master.
DiSEqC Components
If all the switch matrices are in series, the Master
receiver must send the DiSEqC signal a number of
times, so that all DiSEqC multiswitches receive
commands in series.
DiSEqC components (Slaves) have to be compati-
ble downstream, which means that they must also
meet receiver analogue switching criteria which
only accept H/V and 22 kHz command signals.
A DiSEqC switch matrix thus operates with ana-
logue switch criteria until the master sends a DiS-
EqC command. Then, all the analogue switch cri-
teria will be ignored.
DiSEqC 1.2 positioner
With a DiSEqC 1.2 compatible positioner, a dish
equipped with one LNB can be aimed at a number
of satellites. This standard comprises specific
commands for directing dish rotation.
FEC
FEC stands for Forward Error Correction, used to
correct signal transmission faults between the
satellite and your dish.

GLOSSARY

PID
The PID code (Packed IDentification) is the identi-
fication number of audio and video signals in the
digital data flow of DVB MPEG-2 signals. With this
code, the receiver transmits audio and video sig-
nals to a specific address.
The PCR PID code is the identification code of the
synchronisation symbol. It is usually the same as
the Video PID.
Symbol rate
This rate corresponds to the quantity of data trans-
mitted per second. This value is expressed in
Msymb/s and is identical to the number of symbols
transmitted per second.
Transponder
A transponder is a transmitter located inside the
satellite, which transmits radio and TV signals
to the satellite antennas on high level frequencies.
It is defined by its frequency and polarization.
A satellite may have several transponders.
Digital Transponder
A digital transponder can transmit several TV and
radio programs at a time and on the same
frequency. If an operator proposes several TV
programs on one or several digital transponders,
we generally refer to this as a bouquet of pro-
grams. It is defined by its frequency, polarisation
and symbol rate.
Viterbi Rate
The Viterbi rate is used by the operator as a pro-
tection against transmission errors. It is a redun-
dancy of the transmitted information. The DVB
standard includes the following values: 1/2- 2/3 -
3/4 - 5/6 - 7/8.
Eb/No ratio
This parameter expresses the signal/noise ratio of
the digital signal. When the ratio is below 5 dB,
reception is no longer possible.
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