[linux-dvb] KNC1 SNR goes/went bad

P. van Gaans w3ird_n3rd at gmx.net
Mon Aug 13 21:40:20 CEST 2007


On 08/13/2007 02:53 PM, Manu Abraham wrote:
> On 8/13/07, P. van Gaans <w3ird_n3rd at gmx.net> wrote:
>> On 08/12/2007 11:02 AM, Manu Abraham wrote:
>>> On 8/12/07, P. van Gaans <w3ird_n3rd at gmx.net> wrote:
>>>> I know there have been some posts about the card - but I didn't see the
>>>> questions asked I have.
>>>>
>>>> [story you can skip]
>>>> The problem is this: currently I have a KNC1 DVB-S card + cineview CI.
>>>> But it's breaking down, SNR appears to get worse by the day. Bad luck :'(
>>>
>>> Can you please get your hardware details of this card you mention ?
>>> Like which tuner, which PLL, which demod etc. The more detailed, the
>>> better.
>> Everything I can find on the card:
>>
>> Tuner:
>> Philips
>> SU1278/SH
>> 3112 297 12871
>> 212 HJ11 GA00126
>>
> 
> Ok, Will take a look at it, as i get a bit free.
> 
>> If that helps I tried to make a picture:
>> http://img451.imageshack.us/my.php?image=img0612swu6.jpg
>>
> 
> We have enough info now.
> 
> Can you describe the problem that you face ? other than low SNR ? ie
> have you checked whether your cables are okay, Dish is aligned proper
> etc etc ? It will help to avoid a lot of frustration later. :)
> 
> 
> Manu
> 

That's great!

The problems I face: I have a lot of BER, measured with femon -h (with 
my patch applied for decimal readings). The sky is clear. Visiosat Bisat 
G3C dish.

On ZDF on Astra 19,2 east (Astra 1), I see nothing (and I mean 
_nothing_) but green and purple blocks and loud aliens in my speakers 
constantly. BER is into 65000.

On Omroep Brabant on Astra 1D at 23,5 east, I see some bits from the 
image but constantly lots of complete stripes with corrupted MPEG, and 
the audio is also bad. So this stream is also corrupt. BER into 65000.

Now ZDF is one of the weakest transponders on 19,2 east and Astra 1D is 
old so doesn't perform optimal either. But this is not normal.

On BBC One/Two/Three/Four on Astra 2D, and that beam is strong in my 
location, the picture is good most of the time, but once approx every 
minute a small visible corruption passes by. Just as long as it does 
_not_ start to rain, I can follow the program. BER into 65000.

On the Dutch channels on Astra 1 at 19,2 east again, like Nederland 1 at 
12515.25 H (Astra 1G) or RTL 5 at 12343.50 H (Astra 1H) the picture is 
perfect, and BER hoovers and shows 0, 256 or 512 (which is low).

There are also values in between. n-tv on Astra 1 at 19,2 east shows 
around 17000-18000. Perfect picture.

But.. When it starts to rain, the whole party is over.

So that's my problem. When I swap the KNC1 for my Technotrend S-1500, 
all the channels work, including ZDF, perfectly, and the BER is zero 
everywhere, even ZDF works with zero BER. There are many other channels 
that do not work but I couldn't possibly list them all, I don't think 
that would make sense anyway. And sure, there could be a little 
difference in tuner quality and stuff in favor of the Technotrend, but I 
really don't believe it would be that big for cards from the same price 
range. And it's not like Philips is a bad or cheap brand either.

I'm actually not sure the SNR number in femon is low, I was really 
talking about Signal to Noise ratio - with all that corruption and 
horrible performance it has to be bad.

On Windows, I can watch ZDF with the KNC1, but I see some "error" level 
in the  Windows software, that "error" most likely means BER. But it's 
not much. Last time I checked anyway, it's been a while since I've seen 
Windows.

The problem seems to be getting worse, because some days/weeks ago I 
believe I had zero BER at the Dutch channels, and now it's around 
256-512. But the weather, temperature and other stuff also varies, so 
it's always hard to say.

P. van Gaans



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