Calculating the correct elevation of a dish.

nucleus

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From what I could gather, in order to calculate the correct elevation of a satellite dish, I need to know the following parameters:

Dish offset (how do I calculate this?)
Coordinates of my position on earth
Satellite coordinates

From these three parameters I should be able to calculate my satellite dish elevation degrees. After I have this number, I can take an inclinometer and precisely position the elevation of my dish.

Please let me know if this is the correct process of configuring the elevation of a dish, and if there is a calculator for this, or if I have to do this manually, and how.

Thank you.
 

rolfw

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nucleus

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The website you mention does not take into account the dish offset. Which i think is needed to calculate the correct elevation.
 

rolfw

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As I said, find the make of the dish and someone will probably be able to tell you.

what size dish is it anyway?
 

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nucleus said:
The website you mention does not take into account the dish offset. Which i think is needed to calculate the correct elevation.


You cannot calculate it as it is dish dependant


EDIT too slow
 
A

archive10

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You mostly don't really need to.

You could theoretically calculate your elevation as the gentlemen describe above.
But that's mostly an academic exercise.

First use dishpointer to set the azimuth of the dish (roughly).
If you have a prime focus dish the dish should be offset at what dishpointer tells.
If you have an offset dish, then the offset angle is either documented by mfg, or can be gleaned from the angle between horizontal and a line between the LNB and the middle of the dish, when the dish is mounted vertically.

In any case, just get a rough angle, and then do as described in the how-to giudes elsewhere on this site, if you are in-footprint it should not take long to find the satellite, if out-of and using large dishes it will take more patience.
 

nucleus

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Ok, please bear with me, because i am either not making myself clear, or i am asking something that is not applicable. Keep in mind i am new in this satellite game.

Lets assume that i have my dish offset. I asked the company that makes my dish and they gave me the number. And i have also used the dishpointer tool, and found out that i must configure a 43.8 degree angle on my dish.

How do i include my dish offset in my calculations of finding the correct dish elevation?
 

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Not sure if this explanation helps.

Code:
 http://www.satsig.net/22-deg-offset-dish.htm
 

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For an explanation about offset angles and how to calculate them look at this :

_http://www.satsig.net/pointing/finding-dish-offset-angle.htm

In reality, though setting up your dish by this method should get you approximately in the right elevation, manufacturing tolerances will inevitably bring about errors. E.G. I have a small dish fixed on Hispasat at 30°W. Dishpointer tells me it should be at 27.7° elevation. When I've set the dish up using a meter to locate the strongest signal, the scale on the mount tells me the dish is at 35° elevation. I bet that, if I took a reading with an angle finder the dish face wouldn't be at the correct angle either because of the mechanical difference between the manufacturers specification and what the finished article actually turns out to be.

If I were you, I'd forget about calculations and angle finders. Get your meter hooked up to the dish and adjust the dish till you achieve the best signal possible. 99% of the guys using this site do it that way.

Edit : Knew I'd take too long writing that post.
 

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What are you attempting to achieve and what size and type is your dish? This information is important if you want us to help you.
 

sonnetpete

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rolfw

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Ah thanks, so it's a relatively modest offset dish, as mentioned above, forget trying to accurately set elevation, won't really help. but most offset dishes have an angle of 26 to 30 degrees, and hence your dish face will only be leaning back by 15 degrees or so, then use your meter to find a signal by moving the dish slowly from side to side and slightly up and down.

@ nucleus, according to your profile, you have no satellite equipment and not all members have time to go searching for your other posts to find out what equipment you actually have.
 

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So what you are telling me that there is not actual, measurable, specific way of installing a dish. I will have to do everything approximately and hope to get lucky? Depending on dish location, satellite, dish offset and any other relevant parameters, i cannot accurately find the correct elevation and azimuth? And be confident that it will actually work?
 

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nucleus said:
So what you are telling me that there is not actual, measurable, specific way of installing a dish. I will have to do everything approximately and hope to get lucky? Depending on dish location, satellite, dish offset and any other relevant parameters, i cannot accurately find the correct elevation and azimuth? And be confident that it will actually work?
To say that you will only find a satellite if you get lucky is overstating the case but calculations and setting up accordingly will only put you more-or-less in the right position.

With dishes up to about 80cm you may find that setting up according to calculations is as good as you can get due to the relatively wide acceptance angle of the dish and that further small adjustments using a satellite meter do not give any improvements but larger dishes will certainly need a meter for the final few per cent inprovements. In fact, the larger a dish the more difficult it is to set up roughly and the more vital it is to use a meter for final adjustment.

What it boils down to is that the calculations will put you roughly in the right position and then you use a meter for precise sdjustments. After a few dish installations you will develop a feeling where is roughly right and then use the meter at this point.
 

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Ok, thank you for your reply. Hypothetical question:

Lets say i set up my dish and its working perfectly. So i take the azimuth and elevation readings from my dish and configure a friends dish with the exact same parameters. He bought the same dish. Can i assume that his dish will work?

Dont get me wrong. The reason i am asking is because I work in the IT field, and i am used to very specific and measureable configurations, and it really annoys me that i cannot do that with this dish pointing business :)
 

sonnetpete

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If we could be confident that the dish settings matched the calculations there would be no need for a meter to finalise your adjustment. I did infer that your calculations would bring the dish into the correct area for reception but one cannot hope to get the alignment absolutely exact with out the aid of some signal quality readout from a meter for example.

I have to agree with Paul, it does become a lot easier after putting up a few dishes. Over time I've installed about eight dishes here (I'm a hobbyist, not an installer) and only used an analogue needle and tone meter, then since last year a more professional meter similar to that one you have. I've never thought about trying to use calculations to set up a dish beforehand but then I'm not mathematically minded and more of a 'hands on' sort of person. Each to his own I guess.
 

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Like Pete I am just a hobbyist. It's only recently I've bought a proper meter and for many years I used only a Digibox to set up dishes for 28E. The largest I had to do was 80cm and I never had a problem. I guess that maybe I was missing the last few percent but it was quite good enough.

Prior to 28E coming on stream I used to use an analogue satellite receiver and could set up for 19E and 13E without problem. I was even able to position a 1.8m dish against the side of the house to pick up the Nordic transmissions at 1W.

I can understand your frustrations (I work in IT as well) but the hardware is made down to a price and it's up to the installer to position it correctly taking into account any slackness in the mounts or overtightening on one side that sometimes happens. IF you can be sure that the wall or post at your friends is EXACTLY the same for verticality and trueness as yours then there's a very good chance that it'll work as you want. But, as I said, anything larger than 80cm is likely to show up the slight differences in construction and assembly that inevitably occur.
 

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nucleus said:
So what you are telling me that there is not actual, measurable, specific way of installing a dish. I will have to do everything approximately and hope to get lucky? Depending on dish location, satellite, dish offset and any other relevant parameters, i cannot accurately find the correct elevation and azimuth? And be confident that it will actually work?


There is of course a measurable and specific way of installing a dish, but as others have said, unless you are buying extremely well engineered dishes with well marked elevation scales, can guarantee that your mast is absolutely vertical and can line up the azimuth of dish with degree perfect accuracy using a compass, (dishpointer can only be used as a guide, as GPS accuracy is not good enough and the dish normally doesn't have an aiming sight), then the tried and tested rough position, then finalising alignment and LNB skew with a meter or the receiver, will always be the easiest way.
 
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