Forum > Decoders > Installation > explora 2 signal and user bands help
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Old 2017-06-22 , 11:02
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Optimist Optimist is offline
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Join Date: Jul 2012
Location: N/E JHB
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Here's calculations for Jo'burg that Geoff posted a while back, should be close enough for your accuracy needs:

Here they are:
Antenna Alignment

Sunday 28 October 2012

Site name andrew2
Satellite name IS-20

Input Parameters

Site latitude: 26.0023S degrees
Site longitude: 28.1791E degrees

Satellite longitude 68.50E degrees

Satellite Look Angles

Elevation: 36.26 degrees
True azimuth: 62.68 degrees
Azimuth compass bearing: 81.78 degrees
Polarization offset: 53.20 degrees
Path distance to satellite: 38075.91 km
LOS is typically only used for azimuth compass reading and checking for any obstacles such as trees.
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Old 2017-06-22 , 11:40
Geoff D Geoff D is offline
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Join Date: Nov 2008
Location: PTA
Posts: 16,681
Well! I see some on the forum have better than 20-20 vision! It is highly unusual for anyone to be able to see a GSO satellite with the naked eye!

Here is a fairly good reference on the subject for anyone to go and read.

In the above article there is this statement, which someone selectively quoted without understanding what it meant.

Unlike objects in low Earth orbit, geostationary satellites are visible throughout every night of the year, only entering the Earth's shadow for up to 70 minutes per day, around a couple of weeks either side of each equinox. During the same period the satellite tends to brighten over several days, twice a year, when the satellites orientation favors the 'beaming' of the Sun in the direction of the observer.
Typically the satellite will be in the mag. +11 to +14 range (or dimmer), but brightening by several magnitudes when the geometry is favourable (around mag. +5 to +6 is not untypical). One satellite is reported to have briefly been visible to the naked eye at mag. +3 !
The Larger the magnitude is, the dimmer the object is!. The brightening effect only happens during the equinoxes and one is extremely lucky to be able to see a satellite even with a telescope. So in the last few days it might just have been possible for a few minutes but very unlikely with the naked eye.

In our case, most of the LOS distances to the satellite are further than the recognized 35 786 km value. Sites in Johannesburg are about 38076 km away.

Fact is most GSO satellites are just too feint to be able to be seen without a good telescope, occasionally visible with a good pair of binoculars and very seldom with the naked eye!

There is no way you can use this fact as a means to point an antenna!

I will make a point of looking along the LOS tonight with my 3 inch reflector telescope to see what I can see if anything.
Spare decoders: SD PVR(3) PSU's, DSD 660, 1110, 1131, Explora 1.
Spare switches and LNBs: 1 x 5-1(repaired); 1 x 5-2.Numerous so called faulty LNBs that were easily repaired.
2 unmentionable FTA decoders
1.2m antenna, 8-way universal LNB, 2 x (2x6) MS, FSM permanently connected.

Last edited by Geoff D; 2017-06-22 at 11:44. .
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Old 2017-06-23 , 09:00
idm1 idm1 is offline
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Originally Posted by Optimist View Post
The LNB points at the dish, ......
So perhaps I should turn mine around, maybe that's what the problem is, maybe I'll get better signal then.
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Old 2017-06-23 , 10:47
Optimist's Avatar
Optimist Optimist is offline
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Originally Posted by idm1 View Post
So perhaps I should turn mine around, maybe that's what the problem is, maybe I'll get better signal then.
Easy mistake to have made, I realised it was just a typo

BTW, in most circumstances we can use the LNB to align for azimuth, but the arm gives a much better accuracy due to its length and also gives the elevation.

Interestingly in other parts of the world it's not always so simple as they sometimes use arrays of LNBs on one dish for multiple birds (satellites) in close-by neighbourhoods.
Lots of other differences as well.
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