Moderator Control Panel ]

Fetching multiple MIS streams

Fetching multiple MIS streams

Postby titer » Tue Dec 06, 2016 4:03 pm

Hi there,

I have been testing a TBS6908 card for acquiring MIS streams and that has been doing well (thanks to instructions from http://www.tbsdtv.com/forum/viewtopic.php?f=167&t=9707), as I have been able to receive various MIS streams from Eutelsat 5.0W and 12.5W, on Debian 8 with the open source drivers.

One question I have is: looking at for example the transponder http://en.kingofsat.net/tp.php?tp=6583, Eutelsat 5.0W 11637V carries 6 streams. As far as I can tell, the linux drivers & DVB API only let you select one stream at a time, so I would need 6 inputs to receive them all.
Is this a hardware or software limitation, would there be any possibility to extract all streams in parallel from a single input?

Thanks,
Eric
titer
 
Posts: 2
Joined: Sat Nov 26, 2016 12:34 am

Re: Fetching multiple MIS streams

Postby crazycat » Wed Dec 07, 2016 3:13 am

HW limitation, one demod path can process only one TS from S2 frames.

P.S. you can use also 6905.
crazycat
 
Posts: 526
Joined: Mon Jan 31, 2011 2:46 am
Location: Ukraine, Kharkov

Re: Fetching multiple MIS streams

Postby titer » Wed Dec 07, 2016 11:57 pm

Ok, thank you for clarifying that.

Going a little off-topic here, but my understanding from looking at the 6905 and 6908 specs was that, only the latter supports ACM/VCM in addition to CCM, which would be needed for many MIS feeds. Did I get that wrong, and then in which case would one need the 6908?
titer
 
Posts: 2
Joined: Sat Nov 26, 2016 12:34 am

Re: Fetching multiple MIS streams

Postby crazycat » Thu Dec 08, 2016 11:21 am

STV0910BD demod (TBS6905) have restricted support for VCM/Multistream DVB-S2/QPSK,8PSK. So can receive multistream 8PSK transponders with DTT muxes.
"Advanced" demod STV0910AD (TBS6983,6903,6908,5927) demod have full support ACM/VCM DVB-S2/QPSK,8PSK,16APSK,32APSK.
crazycat
 
Posts: 526
Joined: Mon Jan 31, 2011 2:46 am
Location: Ukraine, Kharkov

Re: Fetching multiple MIS streams

Postby igorfreire » Sun Dec 15, 2019 1:51 am

I was looking for information regarding concurrent multistream reception and found this useful post.

I have a DVB-S2 lab setup with a Tx node directly connected to TBS 5927 and the TBS 5520SE receivers and I would like to accomplish something similar: to multiplex two streams and receive them both simultaneously.

The Tx node is sending UDP/IP traffic over MPE, over MPEG TS. At TS level, it multiplexes two PIDs, 32 and 33. All TS packets with PID 32 are sent over DVB-S2 frames using MODCOD QPSK 1/4, whereas all TS packets with PID 33 are sent over DVB-S2 frames using MODCOD 8PSK 3/5. So, in the end, in this scheme (labeled Scheme 1 below) two logical data streams are multiplexed at TS level. On the receive side, then, I instantiate two dvbnet interfaces, one for each PID, and expect to receive the UDP/IP packets sent on the corresponding PID.

In summary:

Scheme 1 (same ISI, different PID):

Stream 1: ISI = 0; PID = 32; MODCOD = QPSK 1/4
Stream 2: ISI = 0; PID = 33; MODCOD = 8PSK 3/5

Using this scheme, I've found that:
- The TBS 5927 correctly demodulates the VCM stream and decodes both MPEG TS PIDs.
- The TBS 5520SE locks randomly to one of the two streams. I don't seem to be able to control which stream/MODCOD the 5520SE locks to using dvbv5-zap.

Due to the problem with the 5520SE, I tried multiplexing at BBFRAME/ISI level. The scheme becomes:

Scheme 2 (different ISI, different PID):

Stream 1: ISI = 1; PID = 32; MODCOD = QPSK 1/4
Stream 2: ISI = 2; PID = 33; MODCOD = 8PSK 3/5

This scheme does allow me to control which stream the 5520SE locks to. All I need to do is set STREAM_ID on channel.conf used by dvbv5-zap. However, the disadvantage is that I don't seem to be able to receive both streams simultaneously when they use distinct ISI as in Scheme 2 above. Hence, although Scheme 2 solves the 5520SE problem (of choosing which MODCOD to lock to), it is a worse solution for the 5927, with which it would normally (in Scheme 1) be possible to receive both streams simultaneously.

crazycat Wrote:HW limitation, one demod path can process only one TS from S2 frames.

P.S. you can use also 6905.


So, is it possible to receive multistream simultaneously with either the TBS5927 or the TBS5520SE? If I understand correctly, the 5927 uses the STV0910 demod that was mentioned above. So I suppose it is not possible?
igorfreire
 
Posts: 2
Joined: Sat Dec 14, 2019 2:53 am


Return to Professional DVB-S2 Quad Tuner PCIe Card TBS6908

Who is online

Users browsing this forum: No registered users and 1 guest

cron