Pixelations on most transponders

[mitch26]

Hi, I have read several threads talking about freezes or pixelations and I want to contribute solving this problem.

I own a Technotrend S2 3200 tuner card and i use DVBViewer pro 4.2.1 to watch the TV programs.

What happens to me is that all channels on transponders with a data rate over 30 Mbps (measured with the analyser function of transedit)loose a high number of blocks (about 10 to 15 per mn)and this seems to cause the pixelation of the picture. Other transponders on the same satellite with a data rate below 30 Mbps do not loose blocks and there is no pixelation.

I am regularly tuned to satellite Atlantic Bird 3 but I have tried ASTRA 19°2 and I get the same effects. I do not think it has anything to do with Windows as I have made the tests with both Win XP 32 bits and Win 7 64 bits and the results are identical. My Technotrend spec gives Max data rates of 60 Mbps for SD and 90 Mbps for HD and its driver is up to date.

The set-up S2 3200 with DVBViewer has been working perfectly in the past but I tried other viewers to be sure and I still get the problem.

Does anyone have good technical knowledge to link data rate with pixelation and how to stop the interference ?

[Derrick]

..don't think that the card or the DVBViewer is to blame. D you run any tools to throttle the cpu?

[mitch26]

My Intel i5 750 CPU (2,66GHz) is normally slightly overclocked to 2,73 GHz to enable my DDR3 DRAM to run at its full capacity (1600 MHz) but when I run the CPU at its nominal frequency this does not make any change to my pixelation problem. Besides, I have run both card and viewer on a different computer and a different O.S and the pixelation is the same. On the transponder where I don't get pixelation, the FEC is 2/3 which probably helps preventing the missing data blocks causing the pixelisation.

[Derrick]

On the transponder where I don't get pixelation, the FEC is 2/3

 

..looks like poor reception. Maybe the dish is too small or not properly adjusted.

[mitch26]

It is a 80 CM dish and it must well adjusted as it's only on my computer that I can't get a good picture : I have one TV set in the lounge and an other in one bedroom each with its own decoder from different manufacturers and they both work well.

[mitch26]

I remember reading on some other thread that when users of ASTRA 19°2 switch to ASTRA 28°2 keeping the same hardware and software, they do not get the problem and I have noticed that on that satellite all transponders have a data rate below 35 Mbps. Am I on the right track ?

[mitch26]

Hi fellow members, I want to summarise my own testing as well as what I have been able to read on DVBViewer forum and other dedicated forums.

 

1/ The artefacts are present no matter which type of O.S (Win 7 & Win XP 32/64 bits) and graphic cards are used.

2/ The problem is common to several types of TechnoTrend cards

3/ When moving the TechnoTrend card to an other computer fitted with different hardware, the artefacts problem moves with it.

4/ Adjusting the dish position and LNB bias for best quality does not change anything to the artefacts.

5/ The problem is common to SD, HD, Crypted and uncrypted channels.

6/ Changing viewer (DVBViewer Pro, TT viewer, TT Media Center) does not improve anything.

7/ Changing Codec (FFD Show, Power DVD, Microsoft DTV-DVD, etc) does not make sensible differences.

8/ The artefacts problem happen on different satellites but sometimes not on all transponders of the same satellite :

- For Astra 19°2E all transponders are affected

- For Astra 28°2E all transponders are OK

- For atlantic bird 3 5°W all transponders are affected excepted those with a low data rate and low SR ( KB 4 : SR 20000/25 mbps - KB 7 : SR10910/18 Mbps)

9/ Stand alone decoders (Humax, Aston, etc) associated to a TV set do not suffer from this problem and the pictures are OK.

10/ The problem did not exist several months ago.

 

Is is difficult to draw a definite conclusion but it seems that something has changed in the transmission specifications of some transponders which make TT cards partly inoperative whilst standalone decoders more recent in design may be better able to adapt to the situation.

Whatever the reason may be, it is sad for DVBViewer customers not to be able to watch some of their favourite TV programmes on computer and I wish that some cooperation could take place betwen DVBViewer and Technotrend in order to find a soution to what seems to be a very intricate Boadcasting specifications problem.

[Derrick]

..but it seems that something has changed in the transmission specifications of some transponders..

 

..definitely not. Except for some new dvb-s2 transponders the modulation parameters on astra 19E haven't changed since the beginning. There could be some issues with too high rates but these are limited to a couple of dvb-s2 transponders mainly on 1W and 23E. Maybe there's something wrong with your card.

[mitch26]

May be but I have 2 cards (same TT model S2 3200) and they behave the same.