Problem to get 8PSK Freqs by DVB S2 Card

HBF86

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Jan 23, 2020
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Tehran
I'm using Prof 7500 usb dvb-s2 card and i'm dealing with the problem of getting noisy & pixelated picture continuously once i start to turn on the existing channels on 8PSK modulation frequencies lately.(attached file)
The singnal strength & quality numbers overally are the same as before and look ok in those frequencies, Although I lose the signal several times for a couple of seconds (especially at first minutes after turning the device on),It goes back instantly then.
While simultaneously, there's no problem on QPSK frequencies (both HD & SD channels) no minor signal lost and the received picture is perfect.
Can I have some guidance to fix the issue please?
 

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johnnynobody

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Aug 2, 2009
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It sounds like windy conditions or too small of a dish or dish alignment. You'll need to check your receivers C/N for that signal and see if it's sufficient for the modulation and FEC that you're trying to receive. I'm not sure if it would be a USB or OS (Windows or Linux) issue.
 
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HBF86

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Tehran
Can it be likely something is wrong with LNB or Cable?
I made sure Dish position and alignment look firm but i'm not sure LNB or cable or the USB device are working in the best state really.
 

Cham

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Do you have a DVB-S2 receiver you can compare with? Suspect the signal will be the same as the card if you do have one. Also if you know someone locally that does get the sat/TP you are interested in you can compare...

The TBS card I use typically gets a better S/N than the S2 receiver(s) I use, but they have a longer cable run and I have (mostly) RG11 between the dishes and my TBS card so it's not really an apples->apples comparison.
 
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HBF86

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Tehran
So I suppose I need to find another receiver to know the cause of the problem. I've just suspected if my DVB-S2 itself is working properly either,maybe a hardware failure in the device unfortunately.
I also tried it out with a newer power supply adapter in same specs and nothing was changed.
 

Martyn

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Sep 25, 2005
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What channels and what's the error correction? It might be that your dish is close to the lower limit and slight glitches than can be handled on other channels are vulnerable.
 
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HBF86

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Tehran
What channels and what's the error correction? It might be that your dish is close to the lower limit and slight glitches than can be handled on other channels are vulnerable.
On every single channel in 8psk the problem comes up , On channels in Qpsk everything is OK indeed ( look like the attachments)
I checked dish alignment as well , It sounds like as usual.
 

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kittyhas1000legs

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Can you adjust the dish and watch the screen, or do you have a meter to connect at the dish? A tiny shift in the position of the dish can make or break an 8PSK signal.
 
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HBF86

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Tehran
It can be true in some way I need to check it up more precisely hopefully there will be chances to figure something out I pressed for time these days though, Unfortunately.
 

HBF86

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Jan 23, 2020
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Tehran
Finally I could just borrow a friend of mine's HD receiver and tried the case out. I never changed my satellite dish alignment or adjusting LNB and something else setup , everything related to antenna was left unchanged during the test indeed , and yes the picture on the screen in every modulation and channels was perfect by the HD receiver . I just found out my problem derives from the dvb-s2 card itself . Replacing drivers and AC/DC adapter (has the same specs) had no effect too.
I was wondering what suggestions would you recommend to try , Thanx
 

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