Brief Technical Glossary, DiSEqC components

Brief Technical Glossary

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 critiera until the DiSEqC™ command from the master is received. All analogue switching criteria are then ignored.

Dolby Digital

A sound transmission method that allows digital surround sound to be output on a home cinema system.

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 MBit/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, reception is normally no longer possible.

FEC

FEC is the abbreviation for Forward Error Correction. The FEC error rate corresponds to the Viterbi rate.

PID

The PID (Packet Identiﬁ cation) number is an identiﬁ cation 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 PID PCR is the identiﬁ cation number for the synchronisation signal. The PID PCR is normally identical to the video PID. For programmes broadcast in multiple languages, the audio PD 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 identiﬁ ed by the PID number from the data stream and assigns it to the video signal.