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Short Technical Guide
DiSEqC™
DiSEqC™ (Digital Satellite Equipment Control) is a communication
system between a satellite receiver (master) and the peripheral satellite
components (slaves), such as LNBs, multi-switches, rotating antenna
systems.
It is a single master/multi-slave system, i.e. there is only ever one master
in the satellite system. All activities start from the master.
DiSEqC™ components
If DiSEqC™ switching matrices are cascaded, the master receiver
must transmit the DiSEqC™ signal several times, so that all DiSEqC™
multi-switches in the cascade receive their commands.
These days, DiSEqC™ components (slaves) must be reverse
compatible, i.e. respond to the analogue switching criteria from receivers
that are only equipped with H/V and 22 kHz control signals.
A DiSEqC™ switching matrix will work with analogue switching criteria
until the DiSEqC™ command from the master is received. All analogue
switching criteria are then ignored.
DVB MPEG-2
DVB is the abbreviation for Digital Video Broadcasting.
DVB-S refers to the transmission method (S = satellite). MPEG is
the abbreviation for Moving Picture Experts Group, a working group
that formulates internationally applicable standards for the digital
compression of video and audio. MPEG-2 has established itself as the
standard for compression of digital TV signals. MPEG-2 works up to a
data rate of 100 MB/s.
EB/NO ratio
The EB/NO ratio is a measure of the signal to noise ratio of a digital
signal. The value is not identical to the C/N value familiar from analogue
reception technology. At EB/NO values below 5 dB, no reception is
normally possible.
FEC
FEC is the abbreviation for Forward Error Correction. The FEC error
rate corresponds to the Viterbi rate.
OTR
One Touch Recording
PID
The PID (Packet IDentification) number is an identification number
for video signals and audio signals in the digital data stream of DVB-
MPEG-2 signals. The receiver uses the PID number to create a unique
assignment for the video and audio data transmission. The PCR PID is
the identification number for the synchronisation signal. The PCR PID
is normally identical to the video PID. For programmes broadcast in
multiple languages, the audio PID can be entered manually to assign a
different language to the TV programme. After the PID is entered, the
digital receiver automatically selects the audio data identified by the
PID number from the data stream and assigns it to the video signal.
Programme package
The programme package for a digital transponder normally includes
several TV and radio programmes. Each programme package has
a fixed assignment for the transponder transmission frequency, for
polarisation (horizontal or vertical), for the symbol rate and for the
Viterbi rate or error rate.