FTA alignment procedures (your expert opinion requested)

[AcWxRadar]

This request is just to solicit your honest opinion regarding a procedure to calibrate a motorized Ku band dish to the satellite arc.

I have read and believe in the recommendation from Tim Heinrichs (CEO of DMS International).

He has suggested and recommended an approach for aligning a motorized dish to the arc. Here is his statement in its entirety:

Tracking the arc with your SG2100
By Tim Heinrichs, HSD, SMM, MRD
CEO of DMS International
January 4th, 2008

Tracking the arc has always been one of the most mis-understood parts of satellite installations. The SG2100 is ingeniously built to follow the satellite arc PERFECTLY if it is properly set to do so.

The SG2100 has a feature called “Go to 0”. It simply drives the motor to a position that should be “0” on the degree of rotation scale of the SG2100. For installation purposes, Go to "0" is a simple way of aligning everything in a nice straight line and should only be used for a starting point. If the "0" point is off, drive the motor using the manual buttons until it is at the “0” position on the motors degree of rotation scale.

But let's not get ahead of ourselves. Always remember, The mounting pole being perfectly plumb and the declination being set exactly on is the
foundation for good tracking. To make your mounting pole plumb you need a good quality level or other instrument that will give you a plumb reading.

Everything you need to know about declination is in the manual that came with your SG2100. Follow the instructions carefully and your declination will be correct. Correct setting of your declination is critical to how your dish will track the satellite arc. Set the declination and tighten the bolts. If you have set it correctly you won't need to move it again.

Now at this time you should have the motor and dish set on the mounting pole and all of the adjustments made carefully following the manual. Here's what I believe to be the best and most accurate method of tracking your dish. It simply gives you a way of matching the satellite arc in space with the arc your dish follows as your motor turns it.
After setting up the motor and dish you will start by pointing the dish south and snugging the motor to the mounting pole. Now motor to the east most satellite that you can get a signal on and adjust your elevation ONLY for best possible signal. Snug the elevation. Motor to the west most satellite and adjust your azimuth ONLY for the best possible signal. Snug the azimuth. Repeat this process until no improvements can be made in signal strength. Each time you make an
adjustment it should be less than the time before. If not, you are doing something wrong.

Of course this is the quick explanation. It will take you a while to get the hang of it and certainly longer to do it than it took you to read this.

If you are a installer doing this often and using the same equipment (same dish), take some readings in the "0" position with your angle finder on this now perfectly aligned motorized system. Take a compass heading of the dish in “0” position. Record the angle of the LNBF support. Record the angle of the motor tube. Now motor to the first satellite close to the “0” degree of the motor and record that setting.

Keep these recorded findings in and safe place and your next
installation will be a breeze. When you go to install your next SG2100 motorized system, simply plumb the mounting pole and motor to “0” position on the SG2100. By using the readings that you took from your first install, set the angle of motor tube and set the angle of the LNBF support. Now motor to the known degree of the satellite and you're
set. Just turn the dish and motor on the mounting pole until you get a signal. You should be very close to perfectly tracking the arc. Check your work using the method described above. You just went from a grueling hour or more of tracking the dish to a smooth 10 minute install.

This will work within a reasonable distance from where you took the first readings. If your service takes you more than 50 miles from the original site (where you took the readings) you may need to make some small adjustments. I certainly hope this helps you do not only faster installs of motorized systems, but more accurate installs.

Good installs are critical to avoiding service calls that don't pay. Faster installs allow you to make more money and be more professional.
Always do your installs on the ground whenever possible. Ground installs allow for better and faster access in case of service calls and they also avoid most dish movement that happens on roofs that tend to warp and buckle in changing weather conditions. A roof mounted dish that moves a fraction of a inch at the base can translate into a inch or more at the top of the dish. The next time you have a service call for a system that has signal in the day time but not at night
(or vice versa), check out where the dish is mounted. I'll bet it's on a roof.

Keep us in mind for your equipment needs. DMS International is the only exclusive wholesaler of the official SG2100. If it doesn't have DMS International on the box and on the labels, it's not the original SG2100.

I wish to recruit your advice, comments and critique of my personal elaboration on Mr. Heinrichs instructions.

I have not yet attempted this, so it is just theory at this point. Please listen to my idea and tell me if you think I am locked onto something valid.

My proposal is that you locate the nearest satellite to true south and set up your dish and motor for the best possible signal and quality level. Set the MOTOR LATITUDE and the DISH ELEVATION and the MOTOR AZIMUTH to fine tune this signal.

Then, (using USALS) motor the dish to a satellite east of your center position and pick out a HORIZONTAL transponder with a consistent signal broadcast. On this HORIZONTAL TP, adjust your DISH ELEVATION to peak the signal.

Next, motor the dish to a satellite on your western horizon and select a VERTICAL TP. When you are able to detect the signal from this VERTICAL transponder, adjust your MOTOR AZIMUTH position to peak the signal level.

Go back and forth between these two satellites and transponders and readjust the DISH ELEVATION for the best possible signal from the HORIZONTAL TP on the eastern satellite and adjust the MOTOR AZIMUTH for the best possible signal from a VERTICAL TP on the western satellite.

When you have peaked the signal from these two satellites, you move on to two new sats which are further east and further west and repeat the process. Adjusting the DISH ELEVATION to peak the signal on a HORIZONTAL TP to the east side of the arc and adjusting the MOTOR AZIMUTH to peak the signal on a VERTICAL TP to the west side of the arc.

Since there is no written or formal procedure that has been proven or adopted, I am wondering if this procedure might have any merit and be applicable in a generic or universal sense.

My dish is already aligned, so I really cannot test this procedure until I set up an entirely new dish and motor from scratch to prove if it works or determine how well it works.

I would like to request your honest opinions on my procedure. Does it make sense, is my approach logical and most importantly, does it work well?

Thanks everyone!

AcWxRadar (Gordy)

 

[AcWxRadar]

I should state that I don't think there is a necessity to do one thing on the east side of the arc and another on the west side. You could reverse these, but I think it is important (in my theory) to adjust the ELEVATION with reference to a HORIZONTAL TP and adjust the AZIMUTH with reference to a VERTICAL TP signal.

Do you see what I am attempting to explain?

RADAR

 

[DJ Rob]

Very interesting!
I will try what you are saying next week when I'm setting up the DG380 I got from Sadoun and let you know how it works.

It is probably a bit more time consuming. And harder to adjust the motor bracket when you have the dish already mounted on the motor.

I usually just use USALS on my closest southern sat and tweak the dish with a cheapie signal meter. I'm done in less than 5 minutes that way and have 61.5-148 locked in.

I'll see if this is more accurate since you never know if the labeling on the motor bracket is exact.

 

[AcWxRadar]

Very interesting!
I will try what you are saying next week when I'm setting up the DG380 I got from Sadoun and let you know how it works.

It is probably a bit more time consuming. And harder to adjust the motor bracket when you have the dish already mounted on the motor.

I usually just use USALS on my closest southern sat and tweak the dish with a cheapie signal meter. I'm done in less than 5 minutes that way and have 61.5-148 locked in.

I'll see if this is more accurate since you never know if the labeling on the motor bracket is exact.

Rob,

That will be great! If you are setting up a new system, you could try this and relay the information back as to whether my idea works well of not. I have this theory in my mind that there should be a universal alignment procedure that everyone can use and get the job done right. But, I need "guinnea pigs" who are willing to sacrifice themselves to try it out and prove or disprove my theory.

Thanks so much for volunteering! Please try to make some official notations as you procede through the process, something to provide good evidence along the way. I am planning on setting up a new motorized dish in a month or so and I am trying to set up a filming of the entire process. I intend to check this procedure then for myself.

Radar

 

[B.J.]

Well... I've always thought that whatever works for people that's fine. However I really think both the Heinrichs method and your method are overly complicated, and I don't think that either work. But that's just my opinion, and it can't hurt to try, and if it works great.

BUT, in my opinion, if you have set the latitude setting on your motor properly, (and properly is usually by adding about 0.6 to 0.7 to your latitude, and using that value for the latitude scale setting), all you need to do is adjust dish elevation on your southern most sat, after using USALS to motor to it, and after "finding" it via crude azimuth adjustments. Then motor to your western (or eastern, doesn't matter) most satellite, and peak that sat using azimuth (I generally manually motor back and forth through it after each peaking adjustment, just in case the motor's zero point is off). And it doesn't matter whether you choose a vertical or horizontal transponder on either peaking adjustment.
At this point, you are DONE.
It is really just a 2 step process. No need to go back and forth to any other sats unless your pole isn't plumb. The big thing though is that you should only adjust your elevation on the south sat, and you should only use azimuth on your western or eastern sat. Absolutely no need to use both eastern AND western sats either, unless you have made a mistake. There are methods where by using eastern and western sats, you can tell what your mistake was, but there shouldn't be a mistake, and I've always thought it was just quicker to start over and do it right rather than waste time motoring back and forth from east to west, etc.

Also, I definately think it's a bad idea to keep playing with elevation and azimuth on any other sats besides your south sat and extreme sat. All it can do is make things worse.

Just do your south sat, western sat, and you're done.

 

[Mr Tony]

so true BJ...thats what I did with my 2nd motorized

put dish up
peaked on true south (93W)
moved dish to 125 to see what signals were
moved to 74 to see what signals were (had issues with ONN but the rest were fine)

done

 

[Sadoun]

It is probably a bit more time consuming. And harder to adjust the motor bracket when you have the dish already mounted on the motor.

I usually just use USALS on my closest southern sat and tweak the dish with a cheapie signal meter. I'm done in less than 5 minutes that way and have 61.5-148 locked in.

That is the best and easiest method to setup a motor. Also, once you set the motor's elevation same as latitude, you don't want to change that. You only need to adjust the Dish Elevation and Azimuth.

USALS is the way to go and any other method will take much longer time to finish.

 

[AcWxRadar]

That is the best and easiest method to setup a motor. Also, once you set the motor's elevation same as latitude, you don't want to change that. You only need to adjust the Dish Elevation and Azimuth.

USALS is the way to go and any other method will take much longer time to finish.

Yes,

Do not alter the MOTOR LATITUDE adjustment. Leave this setting alone.

And, always use the USALS motor control option as well.

RADAR

 

[meatballsub]

quote: BUT, in my opinion, if you have set the latitude setting on your motor properly, (and properly is usually by adding about 0.6 to 0.7 to your latitude, and using that value for the latitude scale setting),...

I'm curious about this statement. Do others also set the motor latitude higher than is called for? I've heard about not messing with it once set, but what if you set if for actual latitude? Just curious...

 

[Mr Tony]

I have no clue how you would set it for fractions of degrees when the degrees are so close to begin with on the motor

 

[B.J.]

quote: BUT, in my opinion, if you have set the latitude setting on your motor properly, (and properly is usually by adding about 0.6 to 0.7 to your latitude, and using that value for the latitude scale setting),...

I'm curious about this statement. Do others also set the motor latitude higher than is called for? I've heard about not messing with it once set, but what if you set if for actual latitude? Just curious...

Basically, if you use your latitude, you'll be off by 0.6 to 0.7 degrees at the far east or west satellites.
Look at Footprints by Dish Size - Latitude Declination Chart - C/Ku-Band Satellite Listing and look at the tables for the so called "modified declination", and/or search here for discussions involving modified declinations.
Many people don't use the modified declinations and get OK results, but often after doing a lot of adjusting.
I agree with what Ice said, ie that it's not really possible to set angles this accurately (although with these new digital levels that were discussed recently it actually might be possible, at least with the motor elevation), however my approach is that at least make sure you round off in the right direction. Ie in another recent post, someone had a latitude of 41.1, and he was told to round off to 41 on the motor. I would tend to round off to 42, since 41.1+0.7=41.8, which is pretty close to 42. Ie it probably doesn't make enough difference to matter, as long as you round off in the right direction, but if you round off in the wrong direction, you'd be nearly a whole degree off on the extreme sats.

 

[AcWxRadar]

Well... I've always thought that whatever works for people that's fine. However I really think both the Heinrichs method and your method are overly complicated, and I don't think that either work. But that's just my opinion, and it can't hurt to try, and if it works great.

BUT, in my opinion, if you have set the latitude setting on your motor properly, (and properly is usually by adding about 0.6 to 0.7 to your latitude, and using that value for the latitude scale setting), all you need to do is adjust dish elevation on your southern most sat, after using USALS to motor to it, and after "finding" it via crude azimuth adjustments. Then motor to your western (or eastern, doesn't matter) most satellite, and peak that sat using azimuth (I generally manually motor back and forth through it after each peaking adjustment, just in case the motor's zero point is off). And it doesn't matter whether you choose a vertical or horizontal transponder on either peaking adjustment.
At this point, you are DONE.
It is really just a 2 step process. No need to go back and forth to any other sats unless your pole isn't plumb. The big thing though is that you should only adjust your elevation on the south sat, and you should only use azimuth on your western or eastern sat. Absolutely no need to use both eastern AND western sats either, unless you have made a mistake. There are methods where by using eastern and western sats, you can tell what your mistake was, but there shouldn't be a mistake, and I've always thought it was just quicker to start over and do it right rather than waste time motoring back and forth from east to west, etc.

Also, I definately think it's a bad idea to keep playing with elevation and azimuth on any other sats besides your south sat and extreme sat. All it can do is make things worse.

Just do your south sat, western sat, and you're done.

B.J.

I do agree with you as that is what I have always done in the past. But, I became curious, after reading Mr. Heinrichs suggestion. Something about it makes good sense to me.

My personal career involves calibrating all sorts of instruments. Within the scope of my previous job, I calibrated Weather Radar antennas for private aircraft. This is much more involved than setting up a motorized dish on the ground as you have to also rely on the gyro of the aircraft to provide you a calibrated signal to be able to calibrate the radar antenna.

The gyro is akin to your plumb mast, so the gyro has to be dead nuts on so that you can calibrate the radar antenna. If the aircraft rolls to the right or left or pitches up or down, the gyro has to send a signal to the RADAR unit to control the elevation and azimuth of the antenna to keep it parallel to the horizon and panning any detected signal out ahead properly.

Basically, the weather RADAR system on board an aircraft does the same thing that a control system for a communication satellite would do if you were on a ship in the ocean. So, as the waves roll the boat to and fro or the ship changes direction, the gyro tells the antenna which direction and how far to move to remain aligned with the satellite in orbit.

Through my experience with weather RADAR calibrations for an aircraft, I believe that Mr. Heinrichs has a very good idea because it is a very similar technique as is applied to aircraft.

The radar weather RADAR on an aircraft just must be much more refined. As the aircraft pitches and rolls and yaws, the RADAR antenna must take a valid signal from the gyro and position itself correctly (maintaining a parallel view of the horizon).

A RADAR antenna not only pans back and forth across the horizon (constantly) to paint a proper picture of any weather out ahead of the aircraft, it also adjusts itself in the elevation axis at the same time for any change in the pitch of the aircraft.

I also calibrated aircraft RADAR units for the Coast Guard. These RADAR units not only mapped weather anomalies, but could also detect a small boat on the ocean for search and resuce missions. The pilot or RADAR operator would adjust the tilt or elevation of the RADAR system so that they could scan the "top of the water" out on the horizon and detect a "blip" that might be a boat that was adrift and in trouble.

You see that weather RADAR antennas onboard an aircraft need to do the same things as a ground based communication satellite does, but just extremely more accurate.

This is where I am getting my idea of aligning a motorized communication satellite (the ground based antenna) in such a manner to be able to pull in more satellite signals with a greater degree of accuracy by being more precise with the calibration technique.

There is a specific procedure to align a weather RADAR unit on board an aircraft, and I believe that there should be a similar procedure for a simple ground based system looking at a communication satellite in orbit.

I am not proposing that anything that we have been doing up to date is incorrect, but could we compose a procedure that would be more precise? If there was a set procedure (taking into consideration which satellites, transponders or channels a person used - in case they were inlcined or offset or weak in power) would you agree that such a procedure would be beneficial?

I guess I am just always looking for something new to experiment with, something unique or helpful or that would improve what we already have. To me, this is a fun hobby, but to keep it interesting and find out new things, I guess I like to experiment further. I hope you understand my direction with respect to this.

Radar

 

[AcWxRadar]

I have no clue how you would set it for fractions of degrees when the degrees are so close to begin with on the motor

Iceberg,

I have determined a method to do this. For my Ku band offset dish using a PowerTech DG-280 motor, I can hang an inclinometer under the belly of the motor and read out the "elevation" angle of the motor.

Since the elevation + latitude angles add up to 90 degrees, I can determine what my actual motor latitude angle is set to down to 1/10 of a degree by doing the math: 90 degrees - inclinometer reading = the set latitude angle.

Of course this isn't as easy as it appears as the belly of the motor may not be the most convenient surface to take a reading on.

However, without the dish and motor tube installed, I can obtain a good reading off the inclinometer. I purposely set my motor so that the latitude angle (pointer) was on a full degree point (like 40 degrees) and when I read my inclinometer it showed 50.0 degrees.

I then checked my reading on the inclimometer at every five degree intervals on the motor latitude scale from 15-65 degrees and the inclinometer readings confirmed that my motor scale was accurate or at least in agreement with the inclinometer that I was using.

Since the inclinometer read out in 1/10's of a degree, I felt that I could trust that to set my motor latitude to that fine of a resolution.

I set the motor latitude so that the inclinometer read 48.4 degrees. My latitude is 41.6N so 90 - 41.6 = 48.4 degrees. It turned out perfect (as far as I can discern). It was definitely better than when I initially tried to estimate the setting in-betwen the motor markings.

Radar

 

[skysurfer]

what's the point of USALS in the process? Just to make sure you are positioned accurately at an extreme east or west sat?

I've been messing with my stab hh120/fs 120cm dish setup for over a month now, off and on.

My tools include a satfinder meter and a stab diseqc controller. I'd set the motor elevation as instructed in the manual, then put the dish on the motor and line it up as best as I could, then peak up on my due south satellite for best signal level, making adjustments to the dish's elevation setting. I get my maximum signal on the meter and then move indoors to see on my spectrum analyzer how I have done. I only got about 12 degrees on each side before the arc fell off. After 2 weeks of various adjustment futzing, I got a pole plumb device and found out my pole was out of plumb, probably due to the the 120cm being much heavier than the 90cm was.

I redid the post to make it more stable and got it plumb. I put the motor back on the post and it stayed plumb. I'm getting a few more sats now but I"m not getting the extreme sats.

What I"m stuck with is knowing what to adjust next. I think I may try the c-band style (elevation for due south, azmiuth for as extreme of sats as I can get). I also don't know if my issue is with not being on the polar axis quite right or if it is related to my dish not being perfectly straight on the motor and I"m trying to reason how I can determine if it's a motor/dish on the pole issue or a dish on the motor issue.

I may try the USALS thing and have it drive my motor to the AMC-5 position and then I"ll see if I can find it by azimuth and try to get the complete arc that way.

 

[Anole]

SkySurfer -
Here is a page out of the STAB manual, regarding what to adjust, based on what you see wrong.
Have you gone through the USALS setup procedure?
Does this drawing help?

 

[skysurfer]

SkySurfer -
Here is a page out of the STAB manual, regarding what to adjust, based on what you see wrong.
Have you gone through the USALS setup procedure?
Does this drawing help?

the drawing only helps marginally -- I've had it printed out and have been using it for the last few weeks.

I can't get any better or worse signal at the best end sats I currently get, so it's not like I can do any of the adjustments on that page. I think my dish may not be squared up on the motor -- maybe off axis by a few mm - but I don't know how to prove that since it's not disclosed on the stab fine tuning page as a symptom and thus the instruction that the dish about the motor adjustment needs to be made.

I haven't done USALS but it's a thought now -- do what I can with USALS and then goto AMC-5 - my extreme east sat - and then try to find the satellite by rotating the dish about the motor. Considering my adjustments done to date after getting the pole plumb, I'm assuming my dish motor elevation, polar axis, and dish elevation adjustments are about as good as they get since I cannot find any signal meter observation to tell me I need to adjust the motor elevation or do the polar axis adjustment per the stab manual fine tuning page.

In place of USALS so far, I've been using my spectrum analayzer to see what the best end sats I currently get are and then using my signal meter and the push/pull at those extreme sats to see what adjustment I need to make per the stab manual.

 

[AcWxRadar]

what's the point of USALS in the process? Just to make sure you are positioned accurately at an extreme east or west sat?

I may try the USALS thing and have it drive my motor to the AMC-5 position and then I"ll see if I can find it by azimuth and try to get the complete arc that way.

Skysurfer,

A quick overview of my long-winded explanation (below) is that USALS eliminates a huge amount of work from the equation, saving time and making the results more accurate.

The purpose of USALS requires the explanation of what USALS really is and does. The acronym (USALS = Universal Satellite Automatic Location System) doesn't explain everything just by itself. From the STAB company, they give a fair explanation (without going into too detailed technical aspects).

DiSEqC 1.2 is a communication protocol (or digital language of commands) and is how your receiver controls your motor.

USALS is a separate system from DiSEqC 1.2, but must use it as the communication link to the motor (a translator if you like).

USALS is actually a math program. It uses the site latitude and longitude and the satellite's orbital position to make calculations. The result of these calculations and some specific instructions are provided to the DiSEqC 1.2 "translator" so that it can tell the motor what to do. What direction to drive and how far.

If your receiver has only DiSEqC 1.2 communication protocol, that means that you must become a part of the interface.

You must use your remote to move (step) the motor until you find a satellite signal and fine tune it by fine stepping the motor east or west, then you RECALCULATE and SAVE the position that YOU found. This SAVES the position of that particular satellite within the motor.

If you want to log in another satellite, you must go through the same process all over again, for each and every satellite.

If the receiver has USALS positioning, it also must have DiSEqC 1.2 communication protocol. However, now you don't have to be as much of a part of the interface.

With USALS, you enter the site's latitude and longitude and select the satellite orbital position. USALS does its calculations and gives the resulting information to DiSEqC 1.2. DiSEqC 1.2 takes that data and tells the motor what to do.

Select any satellite position and USALS will calculate exactly where the motor should go and DiSEqC commands the motor to move to that position.

With DiSEqC 1.2 you need to ensure that the dish and motor are physically aligned to one satellite (preferrably the due south satellite for your location) so that there is some accurate reference point. But, if you want to find all the other satellites, you have to manually step the motor degree by degree until you locate each satellite. Then perform the RECALCULATE and SAVE function for each satellite. Quite a bit of work!

Also, with DiSEqC 1.2, the SAVE function stores each position within the motor. If your motor is replaced or needs to be reset for some fault, all those stored locations are erased and a default position (list) will replace it.

With USALS you also need to ensure that the dish and motor are physically aligned to one satellite (preferrably the due south satellite for your location) so that there is some accurate reference point. However, USALS takes care of all the rest of the satellites for you! It calculates every satellite position to a 0.03 or 0.05 degree accuracy. Your work is extremely reduced!

Also, all of this information is stored within the receiver (the USALS program is resident within the receiver and you just enter your site's latitude and longitude which are stored within the receiver). So, if anything happens to your motor, no problem! The information is still in the receiver.

I am sure that you can see some excellent, obvious advantages already. Mostly labor intensive items, which are eliminated by the use of USALS.

Now, here is the really great advantage of USALS.

If you know that USALS will position your motor this accurately (+/- 0.03 - 0.05 degrees) you may rely upon this to take a great amount of ambiguity out of your alignment process. If you want to drive your motor from 97W to 43.1W, you can trust USALS to move the motor precisely 53.9 degrees to the east. If you are using DiSEqC 1.2 to position the motor, how do you know how far you drove the motor by stepping it? There is a big "vagueness" here, as you can see.

By using USALS, you can remove this discrepancy and thus record some data to make a chart or graph of all the satellites across the horizon. You may draw out a chart like Anole referenced in his previous post (from the STAB manual) that shows the proper satellite arc and the incorrect arc.

If you make up a chart like that with your own data, you can make notes on it reflecting the deviation of each satellite that you tested.

I.E.: Satellite 'X' is too far west and too low, satellite 'F' is too far east and too high, satellite 'M' is too far west and too low, satellite 'C' doesn't even show up and satellite 'P' seems to be right on the mark. Using this information and the data from a lot of other satellites across the arc, you can make a graph of your system's tracking and see the discrepancies in an obvious (visual) presentation. Then, you can compare the graph of your results with something like the charts from STAB's manual and automatically be able to say... Oh! My motor azimuth is too far this direction and the dish elevation is to far that direction. Then you can make the corrections that are necessary.

USALS takes a lot of work out of this process for you. Attempting to do this with DiSEqC 1.2 alone makes it extremely laborious and many people might just give up. That is why STAB developed it, to make it easier and faster and more accurate.

I hope that this answers your question on USALS and gives you some hints as to some things that may help you align your dish and motor better and easier.

Radar

 

[pendragon]

With USALS you also need to ensure that the dish and motor are physically aligned to one satellite (preferrably the due south satellite for your location) so that there is some accurate reference point. However, USALS takes care of all the rest of the satellites for you! It calculates every satellite position to a 0.03 or 0.05 degree accuracy. Your work is extremely reduced!

This is the party line on USALS. However I saw problems on satellites far from true south. I painstakingly realigned my dish and saw exactly the same thing: everything was dead on the arc, but USALS was simply not driving the dish far enough by exactly the same amount for similar offsets east and west.

I did a direct derivation and found the calculations done by my Pansat 9200HD were slightly in error, probably because of a simplification done in their math (e.g. about 0.2 degrees off when the orbital is 40 degrees offset from true south). Curiously BJ tried his Fortec Ultra and it made exactly the same errors. BJ and I separately derived the correct equations and we are essentially in agreement. When I send these more accurate values to the motor, I hit the far east/west satellites dead-on. See:

http://www.satelliteguys.us/free-air-fta-discussion/166471-usals-notebook.html

 

[Babadem]

Excellent work guys!

 

[DJ Rob]

As for trying what was outlined in the first post of this thread...

Today I aligned my dish using that procedure. It seemed like there was a bigger window of signal on my extreme west or east sats. I found that the window of signal was much narrower and the dish alignment was more accurate (and quicker) when using USALS on my most southern satellite.