Finding due south accurately

[colbec]

Just thinking out loud here, but given the number of posts about aligning dishes and problems, I am just wondering about that step after zeroing the motor, mounting on the pole and aligning to due south.

It seems to me that this step is perhaps the most important of all. Unless you start with a zeroed motor and dish pointing absolutely accurately due south then all the rest of the steps can be miles off. Having reset my dishes a number of times I find the more time spent on this alignment the better the result. I don't see how it is possible to point due south with a simple compass, or guess at where south is, I use a sighting compass and spend a good half hour on this step.

Perhaps the more experienced here can critique the following steps to help me improve even more:

1. attach antenna to motor but leave the dish off.
2. ensure that lnb arm is perfectly in line with the motor when mounted.
3. mount dishless motor+lnb arm on pole and point roughly south, do not tighten down
4. sight due south from pole with sighting compass, establish landmark in distance exactly at south
5. stand with back to lnb arm so that lnb is digging into my back
6. walk towards distant landmark as many paces as reasonable
7. turn 180 deg and look back at lnb arm
8. if lnb arm is not exactly in line with motor, go back and adjust by turning motor on pole
9. repeat 5,6,7,8 until the lnb arm is exactly south
10. tighten down the motor and recheck. Moving the motor on the pole past this stage is a no-no
11. mount dish and then go looking for the due south satellite with button on motor or receiver based on signal quality. The only thing that should need adjusting past this point is elevation of the dish.

Comments appreciated.

 

[bill190]

Very good, but I use a handheld GPS (very accurate). I also set the GPS to give the real south heading and not magnetic heading (GPS setup).

I just keep walking from the dish different directions south untl I get actual south. Then I place a rock or something on the ground there.

Then next get the dish pointing at that object.

 

[updatelee]

I allways just pick a satellite close to my true south, tell the ird to goto that sat, then aim the dish for that sat.

 

[stogie5150]

Well, I am hardly an expert only having done two motor installs, but once I knew what my due south satellite was I just set up the motor/dish to hit that satellite, and the rest of the arc fell right in. I didn't worry about a compass and all that jazz, I just hit my due south satellite,tweak the signal, then lock down the motor to the pole. Both times after that the whole arc fell right in. Only thing I use a compass for is when I am looking for a satellite that I haven't hit before.

I hope that helped.

 

[iafirebuff]

This is what I do too. Makes it nice, easy and fast! :up

Well, I am hardly an expert only having done two motor installs, but once I knew what my due south satellite was I just set up the motor/dish to hit that satellite, and the rest of the arc fell right in. I didn't worry about a compass and all that jazz, I just hit my due south satellite,tweak the signal, then lock down the motor to the pole. Both times after that the whole arc fell right in. Only thing I use a compass for is when I am looking for a satellite that I haven't hit before.

I hope that helped.

 

[TiminMb]

I did it like Stogie as well. But I'm wondering if there is a better way, or how to make sure the dish is mounted on the motor shaft perfectly. If the dish is crooked on the shaft, the motor will then be crooked on the pole, and the arc will not be correct. If you get it right, the rest should fall into place.

 

[Anole]

walk the plank

Maybe part of the problem is with people who are unaccustomed to using a compass.
Unless you're a hiker, a boatsman, or a boyscout, it's quite possible to have absolutely no clue.
I never had much occasion to use one, growing up.

There is another thread around here, were I told the guy he was off by at least two degrees with the motor bracket, and he ignored me.
I forget how many degrees of dish elevation he was off.. (8..10?) and that didn't seem to get his attention either.
Little details like that are critical to getting close before you begin the alignment.

I will say how much I liked the idea of walking 10 paces south from the dish and looking back at it.
Just wish I had 10 paces of room to walk in my back yard (without running into a tree, etc).
But what about all those crazy guys putting motorized dishes on their roofs for their first install? . . .

 

[colbec]

In theory, the arc has one point at which the tangent is perfectly horizontal, due south. I envy those people who live precisely on the same meridian as a satellite. Indeed in this case you can point at your satellite and set everything up from that.

If we assume that there is a transponding satellite every two degrees, this puts everybody within one degree of a true south satellite. In actual practice most gaps between satellites are 1,2,3 degrees, the highest is 9 and there are a couple of 5 and 6.

I am at 76 deg 34' which puts me between 74 and 79, a 5 degree gap. Lyngsat says that Galaxy 4R is at 76.8 which would be my due south, but there are no listings there for me to zoom in on.

It puts a greater burden on my setup than you other guys. No wonder I am calculating to the last inch.

 

[updatelee]

you can still hit true south though even if there isnt a satellite at your long.

Im at 123, lets say there was no satellite at 123, then 121 and 127. pick either. tell your ird to goto that sat, lets say 121.

now if you aim your motor for this sat, get it all dialed in with dish elevation and turning the motor east/west. (dont touch the motor elev) then your set. now tell the ird goto goto 0

bamn thats your true south.

see how true south isnt really as important as people make it out to be ? the reason imo that you choose a sat close to your true south is that if you were choosing a sat that is on your extreme east or west that your dish would be skewed ALOT, therfore ajusting your elevation on the dish is accually ajusting the dish east/west quite alot, therfore its giving you a false sence of aim.

 

[iafirebuff]

That sums it up pretty good! I put too much thought into the true south part when I did my first motor setup. I find if I have the tss active transponders scanned in, aim the assembly to the south, slowly move to my tss, I can usually hit it in less than a minute. I use a cheap compass set out about 6 feet or so from my pole, and aim the assembly to the south as a starting point. Then slide her on over and boom. There she is

 

[colbec]

Updatelee:

OK you are starting to persuade me... let's take this example, I read my compass totally wrong and think 127 is my south, 4 degrees off. I set up for 127, pole plumb and motor zeroed, straight up and down. Say go to 127 and the motor moves a bit and bam there I am, I lucked out and the elevation is good. OK so far. But the problem is that since I started out with my dish all trued up and zeroed for south at 127 if I enter an imaginary sat at 123 and tell the motor to go 4 deg east to hit it (go to zero), since I started out with the motor upright I will go left and now be slightly skewed when it ought to be vertical.
In fact it should be the other way around, perfectly vertical at 123 and skewed at 127.

In truing my dish I may note that I can improve the signal at 127 by rotating the lnb, which should be a hint, but that might be just a wonky dish.

I'm sorry if I am being abstruse, but I will have to think on this some more...

 

[Wescopc]

You're making it too hard!

You only have to align the dish to the satellite that has a strong TP with good LOS (Line Of Site). This Satellite doesn't have to be close to your True South Satellite.

Set the dish up, with the motor at zero, aimed more or less to the south. Then motor over to the satellite that you want, using USALS on the receiver.

Align your azimuth by moving the motor mount on the mast left or right. Adjust your elevation by moving the dish up or down on its mount (not the motor elevation/longitude adjustment). Your skew will be correct for the most part, you might tweak it ever so slightly for best signal.

When you are locked on to your satellite - you are done.

I have done this when the house was totally in the way for a South LOS.
Bob

 

[updatelee]

btw your lnb is skewed to 0 deg on a motor, you'll notice when you go east or west that the dish gets skewed, therfore automagically skewing the lnb as well

 

[ChuckBoozer]

Can you still line up a motorized set-up accurately on the arc if you do not have a clear line of sight to due south?

 

[Wescopc]

Yes, you might have to adjust the arc up or down a little. But it will be exactly the same as if you aligned to your True South satellite and had to adjust the arc.
Bob

 

[ChuckBoozer]

Yes, you might have to adjust the arc up or down a little. But it will be exactly the same as if you aligned to your True South satellite and had to adjust the arc.
Bob

Thanks for the clarification. I am curious why it matters that you aim for due south at all? Shouldn't you just aim for the strongest bird you can hit and peak the signal accordingly?

 

[stogie5150]

I think that's because its just easier to deal with as far as skew, most folks get confused with skew before they figure out that the motor does it for them...if they are not clear, the first time the motor goes to the far east or west satellites it will be readily apparent that the dish is skewing itself. I know for me its easier to hit my due south satellite setting up any dish, but usually you can get some kind of signal no matter how the dish is skewed, then bring it in fine tuning the skew ( on a fixed dish, not a motorized, although you can mess it up on a motorized dish by not installng the LNB straight up on your due south satellite. Don't ask me why I know that )

 

[updatelee]

exatly because your true south sat is at the top of the arc, it means your skew is 0, therfore adjusting the dish elevation ONLY ajusts the elevation, where the farther east or west you choose adjusting the dish elevation will also be moving the dish east/west. it just makes it harder to aim.

so can it be done ? defnitly, is it harder ? yes slightly.

motor's can be daughting the first time you set one up, makeing things easier is nice but just take the whole true south thing as a recommendation to make your life easier, its not a requirement.

 

[Wescopc]

Also, because of skew, an offset dish it is hard to figure out just where it is aimed by looking at it.

When it is setting straight up and down you can look at the LNBF arm and see where it is pointed. The more it moves from TS, the more skewed it gets, the harder to visualize where it is pointing.
Bob

 

[Tron]

As long as your receiver has USALS, True South is not an issue. I think what throws many first-time installers off is these two hurdles:

- Pole that motor is mounted to is not ABSOLUTELY plumb (level).

- Relying too much on the elevation scale stamped on the dish.

If you spend time making sure that the pole is dead level, factoring in the weight of the motor once installed, and tweak your dish elevation properly, you will get it