DVB S2 question (1 Viewer)

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techno935

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Jul 27, 2006
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This sparks a question from my earlier post in the Equity discussion. Pardon my lack of knowledge, but why is DVB-S2 harder to lock as opposed to traditional DVB-S. Is the signal weaker? Lost on this one.
 

Mr Tony

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Supporting Founder
Nov 17, 2003
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It isnt harder to pick up. You just need to know the info since there isnt a blind scan box out there that does DVB-S2 right now.

There is a mux on AMC2 (AMC16) that I can lock and its at 99 quality...and thats with a 30" dish
 

SatinKzo

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May 22, 2004
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Iceberg, Can you PM me that info for AMC2/16? I know you can get the signal on the Coolsat 8000 and it's just a data feed IIRC, but if that one is fairly consistent, then I'd like to keep it for reference.
 

Stefan

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Apr 28, 2005
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This sparks a question from my earlier post in the Equity discussion. Pardon my lack of knowledge, but why is DVB-S2 harder to lock as opposed to traditional DVB-S. Is the signal weaker? Lost on this one.

See the Tandberg document I linked to in the other thread. The short answer is DVB-S2 isn't necessarily harder to lock. In fact Qpsk DVB-S2 is likely even easier to lock than regular DVB-S. The problem is NOBODY is using Qpsk DVB-S2. They're all using 8psk and 8psk requires at least 3db more signal to noise margin all else being equal. Of course the FEC rate is a factor as well, but usually even with a more favorable FEC code rate, and the fact that DVB-S2 uses a better performing FEC encoding scheme, that isn't enough to offset this. In the other thread see the comparison I made of a qpsk dvb-s signal with an Fec of 7/8 versus a 8psk DVB-S2 signal with an FEC of 3/4. Even though the 8psk signal has the 3/4 FEC rate it's still slightly harder to lock. Now imagine what the results are when the providers start pushing the FEC rates further to squeeze out even more bandwidth.

Now, I'm not saying you won't be able to lock certain feeds with your existing dish when those feeds switch over to 8psk dvb-S2. There are numerous factors that affect ones ability to lock particular signals. I'm saying we'll have to wait and see. I'm also saying don't be surprised if these signals are harder to lock on your existing dish and perhaps need a bit bigger dish.
 
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dashaund

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Jul 13, 2006
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Travelers Rest, SC
Indyscott

I don't have a lot of info on DVB-S2...I'm sure some here have a greater knowledge that I, I've only just begun exploring. S2 is a newer format and is transmitted different. I don't know the finite information, BUT, from what I understand, it can cram more information in less bandwidth, thus, making it ideal for high definition (or just ideal overall). (It's either the S2 factor 8PSK...like I said I'm not an expert...if someone can fills in the gaps here I'd appreciate it). I don't know if it has the drastic effect that the analog vs digital OTA transmission does, but, efficiency never hurts. Dish network and BEV recently went to DVB-S2 and MPEG4 for it's HD material. The catch is that our current DVB cards can't translate S2 so we must upgrade out cards (or add one). I just ordered the Technotrend 3200. I'll let you guys know about it when I get it Tuesday!
 

photoman76

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Jan 8, 2005
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Neither Dish Network or Bell Expressvu use DVB-S2 for HD. Bell Expressvu still uses DVB and Mpeg2. Dish Network uses 8psk Turbo and Mpeg4.
 

Smith P.

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Oct 4, 2003
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Bay Area, CA
He messed up with Directv.

As for bandwitdh and mux parameters - Dish did some tests using FSS sat with DVB-S2 last year - that IPTV mux was at 60+ Mbps with SR 27000 .
 
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