lnb skew / polarization angle

koansrc

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Thought I'd check the skew angle for my location again but I'm getting varying results (!).

e.g checking for a rounded Lat 38 Long 24 for 28.2E

_www.ses-astra.com/consumer/en/how-to-receive-astra/installation-assistant/index.php gives : +2.1o
_http://www.satsig.net/ssazelm.htm gives : -5.36o
_http://www.smw.se/FreeSoftware.htm gives : -5.2o (although the progam doesn't accept decimals)

which one should i go for :confused
 

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koansrc said:
Thought I'd check the skew angle for my location again but I'm getting varying results (!).

e.g checking for a rounded Long 38 Lat 24 for 28.2E

_www.ses-astra.com/consumer/en/how-to-receive-astra/installation-assistant/index.php gives : +2.1o
_http://www.satsig.net/ssazelm.htm gives : -5.36o
_http://www.smw.se/FreeSoftware.htm gives : -5.2o (although the progam doesn't accept decimals)

which one should i go for :confused

You have the Latt/Long wrong way round

For: Address: Athens, Greece
Latitude: 37.979°
Longitude: 23.717°

dish pointer says +1.9o but I would be inclined to think around -5o as per smv and also thinking logically
 

koansrc

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Yup, mistake in post. Rounded (just for ease) Latitude = 38, Longitude = 24.

But again, how can some calculators give +2 and some -5 ? which is it ?
 

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Well based on my location for Astra 2, one says -14.2o and the other -19.8o :)
 

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Also try :

_http://www.igp.net/Antenna_Alignment/Index.phpz

shows up as -5o LNb offset
 

koansrc

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satelliteman said:
Also try :

_http://www.igp.net/Antenna_Alignment/Index.php

shows up as -5o LNb offset

So it seems it's only the ses-astra site that's giving +2 instead of -5 that all other sites are giving. I wonder why that is ? I would expect the calculations behind the skew to be the results of an exact science ! Unless it's just buggy SW.

On the practical side, I think I'm getting better SNR at -5 compared to +2.
 

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This one is completely reliable:
_http://www.satlex.de/en/azel_calc-params.html?

For: Address: Athens, Greece
Latitude: 37.979°
Longitude: 23.717°

Azimuth angle:
172.74° (True North)
Elevation angle:
45.78°
LNB tilt (Skew):
-5.72°
LNB tilt (Skew):
1.28° (Astra 2A/B/C/D => special case!)
Astra 2 is inclined in orbit ( some say pre- skewed to make minidish adjustment easier in the UK)
 

koansrc

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snap said:
LNB tilt (Skew):
1.28° (Astra 2A/B/C/D => special case!)

I had seen that before but without the explanation I didn't pay much attention ! Great info.

So the ses-astra site *IS* correct after all and all other sites are wrong ( for this particular satellite ).

I guess this means tuning for ASTRA and EUROBIRD is harder than it "should" be.

Thanks snap !
 

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They are just confusing you. The correct skew is about 5-6° as every site says.

They might be pointing out on the SES site is that the LNBs issued to the UK Sky domestic market are housed inside an outer casing making setting the correct skew impossible.

Someone's having a laugh if they are trying to convince you that Astra2 is in inclined orbit.
 

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sounds about right :D
 

koansrc

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Burnham Beech said:
They are just confusing you. The correct skew is about 5-6° as every site says.

You make it sound like a ses conspiracy ...

Burnham Beech said:
They might be pointing out on the SES site is that the LNBs issued to the UK Sky domestic market are housed inside an outer casing making setting the correct skew impossible.

well they've got a map of the world for everyone to identify their location, so why only UK domestic market ? If the sky lnbs don't allow skew adjusting then surely it makes sense that the satellite has somehow catered for this. It matches the rest of the plug and play type of approach of sky and it would be their way of reducing installation errors and problems.

Burnham Beech said:
Someone's having a laugh if they are trying to convince you that Astra2 is in inclined orbit.

I don't know. It makes sense if it's possible.

Perhaps someone could organize a poll :-idea :-idea "How much do you Skew for Astra 2". - just don't say it too quickly...
 
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