Aligning motorized dish without Zenith sat

[k4otl]

This may seem like an exercise in self-inflicted headaches, and I haven't found any info on this, but here goes:
My location isn't great for "looking" at my southernmost sat, which is 82W. I pretty much can't put my C band dish where it can see that part of the arc due to trees (well I could but it'd be 5' off the road, no thanks). For Ku it's not as bad, I can put a motorized dish to see 82W, but it wouldn't see anything west of 110W at best. For C band I chose the location of the pole where I can see 97W-135W (possibly 139W, again, trees). Maybe in the winter I could see to 91W, but not sure.

So, how would one go about aligning a motorized dish when you can't "see" your zenith sat? My idea of doing this is to align the dish's azimuth at the zenith sat, get the elevation/declination as close as one could manage, then drive to the closest sat receivable, if it's right the first time, hooray.
If not, then either adjust azimuth or elevation (you all tell me, I'm thinking elev) till I get a known TP. Then keep motoring through the arc that's visible to see if it lines up, if not, tweak (?) az/elev/declination?

It seems that this would be possible, and that I'm not the only one who has run into this. I don't have the dish on the pole yet anyway and will set it up fixed to start with, then change out for the actuator later (although plans can change!)

 

[primestar31]

This may seem like an exercise in self-inflicted headaches, and I haven't found any info on this, but here goes:
My location isn't great for "looking" at my southernmost sat, which is 82W. I pretty much can't put my C band dish where it can see that part of the arc due to trees (well I could but it'd be 5' off the road, no thanks). For Ku it's not as bad, I can put a motorized dish to see 82W, but it wouldn't see anything west of 110W at best. For C band I chose the location of the pole where I can see 97W-135W (possibly 139W, again, trees). Maybe in the winter I could see to 91W, but not sure.

So, how would one go about aligning a motorized dish when you can't "see" your zenith sat? My idea of doing this is to align the dish's azimuth at the zenith sat, get the elevation/declination as close as one could manage, then drive to the closest sat receivable, if it's right the first time, hooray.
If not, then either adjust azimuth or elevation (you all tell me, I'm thinking elev) till I get a known TP. Then keep motoring through the arc that's visible to see if it lines up, if not, tweak (?) az/elev/declination?

It seems that this would be possible, and that I'm not the only one who has run into this. I don't have the dish on the pole yet anyway and will set it up fixed to start with, then change out for the actuator later (although plans can change!)

I more than once have setup a polar mount, by going out late at night and sighting in the polar star to get the polar axis near perfect.

Now I just do it by looking up local solar noon time, going out to the dish with an atomic clock, and pounding in a long tall stake piece of pipe perfectly leveled some feet away from the dish pole to line up with its shadow at exact solar noon for the site. That stake and satellite pole will then ALWAYS match perfect with True South if you use them as sight points.

Solar Calculator - NOAA Global Monitoring Laboratory

GML conducts research on greenhouse gas and carbon cycle feedbacks, changes in aerosols, and surface radiation, and recovery of stratospheric ozone.

gml.noaa.gov

 

[a33]

My idea of doing this is to align the dish's azimuth at the zenith sat, get the elevation/declination as close as one could manage, then drive to the closest sat receivable, if it's right the first time, hooray.

To add to what Primestar wrote, I would use what I call the USALS-method for a (random) reference satellite, which is partly as you describe:

1. Set motor-axis-at-zero and dish (and LNB arm) exactly in line with each other, with proper axis elevation angle and dish declination offset angle, in the general due south direction, as if you aim at your zenith/apex.

2. a. Rotate the motor axis to your visible (new) reference satellite position, using USALS GotoX command.
b. When you don't have USALS but an actuator, you can measure the relevant distances from the actuator triangle, calculate the rotation angle from due south to your chosen reference satellite (always a bit more than the difference in degrees arc), and then calculate the needed actuator length for the reference satellite. Then go to that actuator length.
c. When not using USALS or actuator length, you could calculate the rotation angle from due south to your chosen reference satellite, and maybe set and measure the needed rotation angle of the axis somehow.
d. Another, rough, method would be: Calculate the rotation angle from due south to your chosen reference satellite (always a bit more than the difference in degrees arc), then calculate the distance that the left and right side of the dish have to move forward and backward (given the width of the dish), and then rotate the motor to that position.

3. When you immediately find your reference satellite, your due south was already very good. Otherwise rotate the whole setup around the pole a bit, to find your reference satellite.
When you have finetuned your reference satellite position, your due south is also good, because of the used angle distance between the reference satellite and the due south position.

4. When still no luck, change the axis elevation a bit, and repeat step 3 on different elevation angles.

I hope you understand the procedure.

Greetz,
A33

 

[k4otl]

To add to what Primestar wrote, I would use what I call the USALS-method for a (random) reference satellite, which is partly as you describe:

1. Set motor-axis-at-zero and dish (and LNB arm) exactly in line with each other, with proper axis elevation angle and dish declination offset angle, in the general due south direction, as if you aim at your zenith/apex.

2. a. Rotate the motor axis to your visible (new) reference satellite position, using USALS GotoX command.
b. When you don't have USALS but an actuator, you can measure the relevant distances from the actuator triangle, calculate the rotation angle from due south to your chosen reference satellite (always a bit more than the difference in degrees arc), and then calculate the needed actuator length for the reference satellite. Then go to that actuator length.
c. When not using USALS or actuator length, you could calculate the rotation angle from due south to your chosen reference satellite, and maybe set and measure the needed rotation angle of the axis somehow.
d. Another, rough, method would be: Calculate the rotation angle from due south to your chosen reference satellite (always a bit more than the difference in degrees arc), then calculate the distance that the left and right side of the dish have to move forward and backward (given the width of the dish), and then rotate the motor to that position.

3. When you immediately find your reference satellite, your due south was already very good. Otherwise rotate the whole setup around the pole a bit, to find your reference satellite.
When you have finetuned your reference satellite position, your due south is also good, because of the used angle distance between the reference satellite and the due south position.

4. When still no luck, change the axis elevation a bit, and repeat step 3 on different elevation angles.

I hope you understand the procedure.

Greetz,
A33

I think I understand haha. I'll be doing this first with the actuator, so I'll be calculating angles/lengths it sounds like. The actuator does work when 12v is applied, I need to check out the sensor circuit and make sure it works fine with my v-box (and not fry anything).

 

[a33]

I think I understand haha. I'll be doing this first with the actuator, so I'll be calculating angles/lengths it sounds like.

I can help with the calculations of 2b and 2c; if needed, I'll give the needed input specifications.

In the meantime, you can use the method with the sun at 180 degrees azimuth, as primestar suggested.
It's just that the sun has to shine, at the specific moment, and be visible at your dish (above the trees, if possible).

Greetz,
A33

 

[k4otl]

I can help with the calculations of 2b and 2c; if needed, I'll give the needed input specifications.

In the meantime, you can use the method with the sun at 180 degrees azimuth, as primestar suggested.
It's just that the sun has to shine, at the specific moment, and be visible at your dish (above the trees, if possible).

Greetz,
A33

Just so I'll be ready once I get the azimuth marked out by the sun... what are the "needed input specs"? I think I have an idea, but you tell me.

 

[a33]

. what are the "needed input specs"?

In the plane perpendicular to the rotation axis (see picture here: USALS for BUDs: ) :
1. distance T-A (I use a positive value for having the actuator at the east side of the axis, a negative value when at the west side);
2. distance A-BB;
3. distance T-BB(zero), when the dish is setup exactly in line with the zero-angle of the axis (even though the setup might not be aimed at south);

These three measures define the actuator triangle T-A-BB, for the Zero-position aiming.

In the line along the actuator itself:
4. distance T-B(zero), when the dish is aimed as in 3. above. (This measurement is used to determine the combined effects of distance B-BB and distance H, when calculating the actual actuator length from the triangle T-A-BB);

Positional data:
5 and 6. the latitude and longitude of the dish location;

And of course:
7. the longitude of the 'wanted' reference satellite (to calculate the USALS angle from).

As the 'simple' USALS angle must be converted to the linear actuator value, it is a bit more elaborate than just calculating USALS angles....

greetz,
A33

 

[arlo]

My long. is 77W and 84W is the closest receivable sat on c band.
With a tube actuator I don't really see how USALS would be useful. Call me wrong.
Get the dish at zenith. I find a flat plane across the dish and digital gauge it until it's level and plumb. That's zenith.
Elevation, declination added. Face pointed true South. Dishpointer works for using landmarks.
Unbolt the motor. Vice Grip the shaft. Setup your receiver or whatever you use.
Since a polar mount tracks the arc. Dishpointer will give you an elevation for any satellite. When the dish is close to your target satellite using a known mechanical reference on the mount. Using a strong sat and tp in your footprint. Time to go hunting.
Then finding the 2nd. sat and tweaking the dish geometry little by little will keep you busy for a bit.
The Tracking the Arc document floating around here helps a whole lot.

 

[Titanium]

I also do not understand the reason to use the USALS protocol to calculate positioning with a Reed switch pulse count linear actuator.

Use the sun's position and feedhorn shadow to determine where the dish is aimed. Simply motor the dish until the shadow of the feed falls on the vertical axis of the reflector. Take note of the exact time and use this calculator to determine the exact longitude that the dish is aimed with one of the dozens of solar position online calculators. Example: Calculation of sun's position in the sky for each location on the earth at any time of day

 

[a33]

With a tube actuator I don't really see how USALS would be useful. Call me wrong.

The beauty of the "USALS method" is that you use the exact distance of a (random) reference satellite to the zenith/apex satellite position, so that when you found that satellite, the due south aiming is also correct.
And you are not dependent on the sun shining, or not.

With a USALS motor, this method is very simple. With an actuator, it is less simple.
But everyone can choose the method he/she likes, of course.

Knowing the actuator triangle measures, also gives the opportunity to know at what actuator length to find any satellite position you want.

Greetz,
A33

 

[a33]

Use the sun's position and feedhorn shadow to determine where the dish is aimed. Simply motor the dish until the shadow of the feed falls on the vertical axis of the reflector.

For a prime focus dish, that is clear.
How do you use this sun method with an offset dish, moved by an actuator?

 

[arlo]

I'd say 2 things. Slap up some good photos. Good ones showing the side if the dish with the lnb mounted. And. Is your dish the one in your equipment listing at the bottom of your profile?
I would suspect the dish, being now on a polar mount, is mounted parallel with the polar angle of the mount.
Do you happen to have the original pole mount handy? I didn't see much on Hughesnet dish look angles.

In the whole trigonometry thing. I think, looking back at the link. Magic Static said it best. I suck at it.
But hey. TGFOC....thank God for online calculators.
Raven/Channel Master offset feed dishes. Look angles are known. I could never fathom letting a 12' offset fed fiberglass dish flop around with mirrors and ratchet straps and stuff trying to figure out the look angle. Much later using machine shop instrumentation.
Get it setup. Find your first sat. Find your second one. And so on. Hit the office supply for a stainless protractor. Stick it to the pivot that turns with the dish and make a pointer. With your latitude angle set at zenith and the pointer pointing at it.
Later on. Figuring out that from 131 to 129, 129 to 127, 127 to 125 is around 125 encoder pulses.
Higher up from 105-103, 103-101, 101-99 you get 115 pulses or thereabouts....interpolation. There HAS to be a sat in there somewhere.
Then as she gets higher in the air into no mans land from around 91-84. It's 90 pulses. And so on and so on over the top from 61 to 58.

Some time ago I helped a Brit setup a Raven offset dish on a H-H mount. I think he's who Jethro Tull wrote Thick As A Brick about.
Jeez. His last name might been Lucas from Lucas Electrics.
Elevation (latitude) plus declination PLUS look angle. Blimey!
He got it eventually.

I DID like the reference to using the stars at night..duh...night!! To setup a polar mount. Because I'm also kind of okay with astronomy and equatorial mounts. Which is basically what a satellite dish polar mount is. Just add the words Modified and German to Equatorial and Bob's your Uncle.....and again...mom knows better. "Uncle Bob" too. Dad's away assignments used to be so long. TDY.

Pi delta arc-sine. I'm lost. An accurate digital angle gauge with magnetic base, or hey. A spare rifle scope, some Velcro straps, duct tape, and a starry night. And a cold Sammy Adams? I'm there. Perhaps a sat finder phone app. And a few figure-eights.

 

[Titanium]

For a prime focus dish, that is clear.
How do you use this sun method with an offset dish, moved by an actuator?

I may have misunderstood the poster's question, but thought he was installing a C-band prime focus.

 

[k4otl]

I may have misunderstood the poster's question, but thought he was installing a C-band prime focus.

Yeah the Hughesnet dishes are remaining stationary. I will eventually motorize a Ku dish of some sort, I've got the motor, but not in a hurry. I am working on installing the 10' C-band dish. I've got a v box (as well as the analog receiver) and the actuator works. When I get some free time (and help), I'll get the 10 footer mounted on the pole and go from there. Thanks for all the info!

The original question was asking about both an USALS Ku dish or a BUD and the fact I don't have good LOS to zenith sat (82W). The BUD comes first (within a week). USALS Ku much later (months?).