[linux-dvb] Re: [Fwd: Re: Re: Twinhan DST / TS204 and signal quality questions]

[Manu Abraham <manu@kromtek.com>]

On Monday 16 Aug 2004 8:36 pm, Werner Johansson wrote:
> Manu Abraham wrote:
> > 		Is there something that we can do to measure the signal level
> > output(using a spectrum analyzer) from the tuner ? Can we check the
> > signal level from the inside stages of the tuner (Output stages of the
> > TSA 5059/ ZARLINK SL 1952 or even a tap from the AGC of the STV0299) ?
>
> I guess most tuners has at least some analog AGC/signal strength output,
> but is it relevant information we get there?


	You have RFA and RFB outputs from the Zarlink 1952 chip, this stage comes 
before the AGC on the STV0299.

> > 		What i have seen is that the signal quality/level what you receive on
> > the Twinhan frontend is much lower than that of a conventional STB's.
> > Even with conventional STB's in my region we have a problem with STB's
> > that employ the tuner from LG. We have a low signal on the Hotbird
> > 1,2,3,4,6 satellite. So therefore viewing Hotbird channels on a LG based
> > STB is not a pretty good idea, unless you have a pretty large antenna,
> > whereas you don't have any problems on Nilesat, Arabsat etc. I believe
> > that's one of the reasons why LG STB's don't sell well in this region.
> > The same goes for Samsung LNB's.
>
> I see, what tuner are Twinhan actually using? As they're having their
> own ASIC on front of the tuner it seems that they can pretty much use
> what they have available?



		I have a strange feeling that it is a LG tuner, eventhough i never got to 
open up a LG tuner.



> Also, interesting note about LG, might be an LG tuner on the Twinhans..
>
> :) Could it possible be that the LG tuners are more susceptible to phase
>
> noise than other vendors? This would explain why Samsung LNBs (with
> potentially high phase noise) would also be a bad idea? Lots of people
> thought that they should be able to reuse their "analog" LNBs when going
> for digital, only to find out the horrible phase problems (good signal
> strength but crap reception)...
>
> > 		The Twinhan tuners also behave much like the LG tuners when you have a
> > bad signal. Even when i don't have a picture on the Twinhan card, i can
> > watch the same channel on a conventional STB.
>
> My experience exactly, even though I thought I had OK signal to begin
> with, but it might be marginal (I get loss of signal even on the STBs
> when really heavy rain comes in, but otherwise it's perfect)



		I get loss of signal on high humidity conditions, usually happens early 
morning.

Regards,
Manu


> > 		It is right that at the driver level there's nothing that can be done,
> > since it can only rectified by the company that manufactures the tuners
> > (not the cards).
>
> That's true... Definitely a hardware limitation..
>
> > Regards,
> > Manu
>
> Regards,
> Werner