Re: [linux-dvb] [PATCH] stb0899: Set min symbol rate to 1000000

From: Manu Abraham <abraham.manu@gmail.com>
To: Goga777 <goga777@bk.ru>
Cc: linux-dvb@linuxtv.org
Subject: Re: [linux-dvb] [PATCH] stb0899: Set min symbol rate to 1000000
Date: Sat, 22 Nov 2008 00:45:27 +0400	[thread overview]
Message-ID: <49271DE7.4020809@gmail.com> (raw)
In-Reply-To: <20081109212526.677d5c76@bk.ru>

Goga777 wrote:
> Приветствую, Manu
>> On Sat, Nov 8, 2008 at 1:30 PM, Igor M. Liplianin <liplianin@tut.by> wrote:
>>> I can receive 3 mSym/s streams. So why do you limit frontend
>>> capabilities to 5?
>> Lower than 5MSPS goes below the Half Power bandwidth characteristics.
>> Usually we have limits defined within the characteristic region,
>> rather than absolute limits at which tuning fails
> 
> 
> that is strange limitation , there's a lot of dvb channels with streams less than 3 mSym/s
> for example on cx24116 & HellasSat 39E we have follow results with xmlscan from Darron 
> http://hg.kewl.org/xmldvb/
> 
> 1=ARM 1;FT GLOBECAST:11109:VC23M2O35S0:0:3418:1235:1335:1
> 10170=AL-IRAQIA ATYAF;IMN BAGHDAD:11642:VC34M2O35S0:0:2175:33:36:10170
> 10180=ALFORqan;IMN BAGHDAD:11645:VC34M2O35S0:0:2180:308:256:10180
> 10180=AL-IRAQIA SPORT;IMN BAGHDAD:11652:VC34M2O35S0:0:2535:2007:36:10180
> 1=LIDER TV AZERBAIJAN;TANDBERG:12520:HC12M2O35S0:0:4340:513:256:1
> 66=EMOTION ART;EMOTION ART:12543:VC23M2O35S0:0:3333:48:49:66
> 1=Medi1SAT;TandbergTV:12545:HC56M2O35S0:0:2734:308:256:1
> 1709=EURONEWS-FRANCE;GLOBECAST:12558:VC23M2O35S0:0:8138:920:930:1709
> 4201=EURONEWS-AFRICA;SESAT:12558:VC23M2O35S0:0:8138:4221:4231:4201
> 1=Tandberg Service;TandbergTV:12591:VC34M2O35S0:0:2170:308:256:1
> 1=VIDEOLINA SAT;Tadiran Scopus:12596:VC23M2O35S0:0:2500:4194:4195:1
> 1=JSC Contribution;Service Provider:12610:VC34M2O35S0:0:2894:200:201:1
> 1=Al Jazeera;Arqiva:12614:VC34M2O35S0:0:2894:311:256:1
> 2=ZAGROS;Unnamed:12625:VC34M2O35S0:0:2668:33:36:2
> 
> will be nice if stb0899 cards also can LOCK low symbol rate channels

The STB0899 and family do use the tuning algorithm completely in
software, rather than a hardware implementation. The algorithm is based
on many parameters based within the driver parameters.

Currently the STB0899 driver doesn't use a tuning algorithm which does
work at low symbol rates. There is an algorithm specified by STM for the
demodulator to go down as far as 2MSPS at Half power, but this needs
some more changes in the tuning algorithm. There wasn't any significant
interest on this by any of the users and this low bitrate algorithm was
never deployed. If there is significant interest, the low bitrate
algorithm can be deployed.

Regards,
Manu

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