DiSEqC
DiSEqC (Digital Satellite Equipment Control) is a communication system between the Sat receiver (master) and the peripheral Sat components (slaves), such as LNBs, multi-switch, motorised antenna systems.
This is a single master/multi-slave system, i.e. there is always only one master in the Sat system. All activities emanate from the master.
DiSEqC components
When DiSEqC switching matrices are cascaded, the master receiver must send out the DiSEqC signal several times so that all DiSEqC multi-switches in the cascade receive their commands.
Nowadays, DiSEqC components (slaves) must be retro-compatible, i.e. they must also respond to the analogue switching criteria of receivers which are only equipped with the control signals H/V and 22 kHz.
A DiSEqC switchover matrix operates with analogue switching criteria until the DiSEqC command is received from the master. All analogue switching criteria are then ignored.
DVB MPEG-2
DVB is the abbreviation for digital video broadcasting. DVB-S refers to the type of transmission (S=satellite). MPEG is the abbreviation for Moving Picture Experts Group, a working group which draws up internationally valid standards for the digital compression of video together with audio. MPEG-2 has been promoted to the standard for the compression of digital TV signals. MPEG-2 operates at a data rate of up to 100 MBit/s.
Eb/No ratio
The Eb/No ratio is a measure for the signal-to-noise ratio of the digital signal. This value is not identical to the C/N value as known from analogue reception technology. As a rule, reception is no longer possible at Eb/No levels below 5 dB.
FEC
FEC is the abbreviation for Forward Error Correction. The FEC error rate corresponds to the viterbirate.
PID
The PID number (Package Identification) 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 establish distinct allocation of the video and audio data transmission. PID-PCR is the identification number for the synchronisation signal. PID-PCR is normally identical to PID video. In the case of multi-language channel transmissions, by means of manual entry of the audio PID, it is possible to allocate another language to the TV broadcast. After entering the PID, the digital receiver automatically selects audio data from the data stream identified by the PID number and allocates these data to the video signal.
Programme package
The programme package of a digital transponder mostly contains several TV and radio channels. Each channel package has a fixed allocation with regard to the transponder transmit frequency, the polarisation (horizontal or vertical), the symbol rate and the viterbirate or error rate.
Symbol rate
The symbol rate describes the amount of data transmitted per second. The symbol rate is measured in MSymbols/s and is equal to the number of symbols that are received per second.
