[linux-dvb] Technotrend S2-3600 HDTV-S2 USB 2.0

Manu Abraham abraham.manu at gmail.com
Thu Jul 19 02:19:14 CEST 2007


On 7/19/07, Erich Newell <erich.newell at gmail.com> wrote:
> I am very happy you inquired. I had planned on using the device with
> clear DVB-S2 transmissions on Echostar1. However, after your inquiry I
> thought I might double check my facts.
>
> In the end I discovered that although the streams are otherwise the
> same as DVB-S2 HD streams in Europe, here they use "Turbo-FEC" rather
> than LDPC!
>
> Very disappointing.

It is not the FEC alone. the basic concept is that 8PSK modulation != DVB-S2

If you are interested in reading a bit more on DVB-S2
http://www.linuxtv.org/wiki/index.php/DVB-S2. We had set this
information up, while we debated on the API changes required for
DVB-S2

In th US, you have 8PSK modulation with Turbo FEC, which is a variant
of DVB-S alone, rather than having anything to do with DVB-S2.

The reason why they employed it is to reduce piracy of their media
(eg: read Dish Networks and friends) since the chip that can
demodulate it is the Broadcom BCM4500
http://www.broadcom.com/products/Satellite/HDTV-SDTV-Video,-Graphics-&-Receiver-Products/BCM4500

Now the fine aspect is that Broadcom won't see their chips to PC card
manufacturers, probably an understanding between the media provider
and them.
This was confirmed to me (while i started working on the STB0899) by
the erstwhile R&D director for Twinhan while they were looking at
chips for DVB-S2 / 8PSK. That was about 18 months back, maybe
situation has changed now.

But some intelligent guys got tuners out of them which can be
connected through a USB interface adapter instead of a regular PC
card. the Genpix 8PSK device is one such. Don't know whether anything
similar exists.



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