[linux-dvb] DVB-S2 Multiple logical TS on the same frequency

Johannes Stezenbach js at linuxtv.org
Mon Oct 15 15:55:51 CEST 2007


On Mon, Oct 15, 2007, Manu Abraham wrote:
> Johannes Stezenbach wrote:
> > 
> > I'm very confident the output of the demod is a single TS in all
> > cases, and this has nothing to do with the demux.
> 
> Maybe, not very sure on that. Also the specifications additionally adds this:
> 
> 5.2 SDTV and HDTV broadcasting with differentiated channel protection
> 
> The DVB-S2 system may deliver broadcasting services over multiple Transport Streams, 
> providing differentiated error protection per multiplex (VCM mode) (see note). A typical 
> application is broadcasting of a highly protected multiplex for SDTV, and of a less 
> protected multiplex for HDTV. Figure 17 shows an example configuration at the transmitting
> side. Assuming to transmit 27,5 Mbaud and to use 8PSK 3/4 and QPSK 2/3, 40 Mbit/s 
> would be available for two HDTV programmes and 12 Mbit/s for two-three SDTV programmes.

That doesn't contradict what I said at all.

E.g. the HDTV TS is packaged with ISI 0x23 and the SDTV has ISI 0x42.
The ISI for each TS is in the EN 300 468 S2 delivery desc.

When receiption conditions are good you can receive both TSs,
when they are bad you can only receive the SDTV TS (the HDTV
one will have too many errors).

In all cases the output of the demod is a single TS.


Johannes



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