Vertical polarisation - low signal

[UyduMan]

Hi all,

Further to my "where is sky news" post, I did some more investigation.

Back ground:
SKY dish pointing at 28.3 (astra) with quad output LNB
SKY HD box in lounge using two of the quad feeds from LNB
Openbox S9 in bedroom using one of the feeds from the quad LNB.

I have no problems with the SKY HD box what so ever. All expected channels received cleanly, no break up.

On the openbox s9, however, I'm having problems receiving vertical polarised channels on the higher frequencies.

By monitoring the signal levels form the 'transponder' menu, I was able to determine that vertically polarised transponders form 10847 Mhz (inclusive) on wards have a very low signal level.

So, because SKY News is on transponder 12207 Mhz V, I'm unable to receive it.

No problems with the horizontal transponders at all.

As an experiment, I disconnected the satellite cables from the SKY box to see if it made any improvements on the the openbox. No improvements were observed.

If the dish was misaligned, surly I would have problems on the SKY receiver too wouldn't I?

Also, I tried connecting the openbox to one of the satellite feeds in the lounge. Known working cable. It made no difference. Still low signal on higher frequency vertical transponders.

Any help would be most appreciated.

[Data7]

I have this problem as well but I have a horizon sat meter to play with. the main problem is a combination of skew of the lnb and power level of the signal. the installer has set up the dish with the lnb in the wrong place and got the maximum power level for the horizontal or vertical instead of checking the BER bit error rate (amount of back feed from wrong polarisation). you need to set your dish up square with the bubble indicator and set the skew off set to number 3 out of 5. and realign the dish. the problem with the openbox/skybox/solomend is the new firmware cuts the signal off completely when it drops below 50% my other dm boxes show 45% on the missing channels but show the channel anyway.

[UyduMan]

I have this problem as well but I have a horizon sat meter to play with. the main problem is a combination of skew of the lnb and power level of the signal. the installer has set up the dish with the lnb in the wrong place and got the maximum power level for the horizontal or vertical instead of checking the BER bit error rate (amount of back feed from wrong polarisation). you need to set your dish up square with the bubble indicator and set the skew off set to number 3 out of 5. and realign the dish. the problem with the openbox/skybox/solomend is the new firmware cuts the signal off completely when it drops below 50% my other dm boxes show 45% on the missing channels but show the channel anyway.

Thanks for replaying mate.
When I was up at the dish last weekend, I did notice that the bubble wasn't dead centre. I didn't think it was that important. The LNB at the dish is also skewed at an angle, which I think it should be.

Is there a way to set the skew on the openbox from a menu? Because I don't get what you mean by '3 out of 5'.

[citygent1911]

Thanks for replaying mate.
When I was up at the dish last weekend, I did notice that the bubble wasn't dead centre. I didn't think it was that important. The LNB at the dish is also skewed at an angle, which I think it should be.

Is there a way to set the skew on the openbox from a menu? Because I don't get what you mean by '3 out of 5'.

If you look at the lnb, it should have some numbers marked on it which tie in with a little arrow on the lnb bracket.

Would this situation improve with a larger dish? Sounds just like my ongoing problem...

[UyduMan]

Thank for the explanation.
I check the skew this morning at it is as you say. The little arrow is pointing at 3. I played about a bit with the skew and dish only to make it worse. So I put it all back to original position.
I will buy an in-line booster see if that helps. Otherwise its going back.

[southpaw]

I found an awful lot of f w 's from post may 2011 had issues in lower signal quality, try a earlier f w and see if it improves, however you will be stuck with lip sync an reboot issues then

[RalphMcT]

Hi Uydu, check out this post http://www.digital-kaos.co.uk/forums...0/#post1245571
I've found a solution of sorts to what seems to be the same problem.

[UyduMan]

Hi Uydu, check out this post http://www.digital-kaos.co.uk/forums...0/#post1245571
I've found a solution of sorts to what seems to be the same problem.

Thanks for the link Ralph.
Funny how the signal meter allows the receiver to pick up the missing channels.

Now correct me if I'm wrong. A signal meter should attenuate the signal. Right? Unless the signal meter has a built in booster....

Looking at the working transponders signal reading form the on-screen menu, they are about 85+% on signal strength. Now I'm wondering, when I switch to the higher frequency v polarised transponders if the signal strength goes so high, i.e. 100+%, that the tuner overloads and is unable to decode.

So, do we need a booster or an attenuator to fix this?

[UyduMan]

Update and closure:
After messing about with the S9 box for two weeks, upgrading and downgrading firmware, upgrading coax to higher quality, optimising dish and lnb setup using a satellite meter, etc I had no success of making it work. I gave up and sent it back to the supplier for a replacement. Yester day I received the replacement S9 and all working problem free ***8211; apart from lip sync on HD channels which I***8217;m sure a firmware upgrade should fix.

So if anyone out there has an S9/S10 refusing to pick up V higher frequency transponders (e.g. Sly News 12207Mhz V), don***8217;t spend too much time on it. The unit is more than likely to be faulty. Just send it back.

Thanks to all who contributed.

[dirtydonki]

Had this on my S10. Turned out to be the LNB Skew.