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.