Setting HH motor Latitude (1 Viewer)

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AcWxRadar

Thread Starter
SatelliteGuys Pro
Apr 26, 2006
4,575
4
40 miles NW of Omaha. Omaha?
Here is the myth: Once you set the motor lattitude, don't ever change it.

Here is the reason why this is a myth: You have to set it correctly the first time!

How do you overcome this so that you set it correctly the first time?

First of all, you need to understand that the motor elevation the motor latitude angles add up to 90 degrees. Ok, that is simple.

Now, you have to know that your motor latitude must be set to the same degree as your site latitude coordinate. If you live at 87.4 W longitude / 42.5 N latitude, then you must set your motor latitude to 42.5 degrees.

Now, why is this a problem for so many people? It is because of two items...

1] The mast or post that the motor is attached / mounted to is not plumb. This screws all angles period! You simply cannot start with this condition. Reset the mast properly to correct this problem.

2] The angle markers on the motor bracket are not refined or precise enough to determine if you are truly set at 42.5 degrees latitude. You may be at 42.3 or 42.6 or 42.7 degrees. How will you judge this accurately so that you know you are right on the mark?

Ok, what needs to be done in the case of item #2 is to remove the dish and motor tube from the motor. Then, slap a inclinometer (a good quality one) on the belly of the motor and read out the degree shown. This is going to be the motor ELEVATION! Now, remember that I said that elevation + latitude = 90 degrees. You want to set the motor LATITUDE to your site's LATITUDE.

However, the inclinometer is reading motor ELEVATION. Therefore, you must subract that from 90 degrees to know the latitude angle that you are setting the motor to.

In this scenario or example, we want the motor latitude to be 42.5 degrees. So, set the motor ELEVATION as read from the inclinometer to read 47.5 degrees and you will then be correct. 90 - 42.5 = 47.5.

Now, when you have this latitude angle set, you will know that it is correct and NOW you do not move it (ever).

The biggest problem with this is that it is hard to judge if you are attaching the inclinometer on the motor belly properly to get an accurate reading. You cannot really do this with the dish reflector attached nor with the motor tube attached. This is a preliminary step that must be done prior to attaching those components.

The inclinometer must set fully flush and parallel to the flat bottom of the motor housing. Motors may vary in style and make this more difficult if they have raised areas on the belly of the motor. Keep this in mind and apply the inclinometer as needed to read the accurate motor elevation. The seam along the side of the motor where the upper and lower shells of the motor housing meet is an excellent leveling marker, if you can figure out how to utilize it.

A highly accurate inclinometer will allow you to get the motor latitude set correctly if you do it right.

Once this is accomplished, then DO NOT CHANGE IT EVER.

The motor latitude and the plumb of the mast are two of the constants that you must adhere to. If you get these two items set correctly, then you only need to set the dish elevation and the motor azimuth variables to dial in a satellite signal.

The dish elevation and the motor azimuth are the only two angles that you should adjust to peak on a signal. You might need to dabble slightly with the LNBF polarization and focal point (distance from the dish). Adjusting the LNBF is the last step as it would provide the very finest tuning portion of the setup.

The LNBF polarization should be set to ZERO degrees on a motorized system and the focal distance I would personally set to the middle of the range and adjust it later for best signal reception. You souldn't have to worry much about the focal distance unless you are trying to pull in a very weak signal for your location. 90%+ of the time, it is just right.

This isn't too difficult, but you have to have a mental picture of what the signals / angles are doing in order for it all to make sense. If you are adept at framing a house, or a roof and trusses, you will understand angles in this way just fine. Geometry is your frend! :)

RADAR
 
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Blindowl1234

SatelliteGuys Pro
Dec 16, 2008
2,034
90
SouthWest Ohio
Radar, Well lets just say I got mine lined up this spring and I'll never touch it again! I hope. I'd have to say for a newbie last fall, getting my SG2100 set correctly was harder than I thought. I really do need to move it a little farther west down the fence line so I can get 74W and 72W. i've got fixed dishes on those sats now. Maybe a spring project. It is a must to have the pole plumb and solid thats for sure. I finally learned if it's working leave it alone lol. Blind
 

AcWxRadar

Thread Starter
SatelliteGuys Pro
Apr 26, 2006
4,575
4
40 miles NW of Omaha. Omaha?
Radar, Well lets just say I got mine lined up this spring and I'll never touch it again! I hope. I'd have to say for a newbie last fall, getting my SG2100 set correctly was harder than I thought. I really do need to move it a little farther west down the fence line so I can get 74W and 72W. i've got fixed dishes on those sats now. Maybe a spring project. It is a must to have the pole plumb and solid thats for sure. I finally learned if it's working leave it alone lol. Blind

I hear you, BlindOwl!

Setting up a fixed point dish can be tough for a person who is just starting out, and then setting up a motorized dish is just 30 times more difficult! I say 30 times as I am able to to pull in at least that many Ku band satellites with my motor now, so I need my dish and motor properly aligned to do this.

What I wish to convey to all FTA enthusiasts and hobbyists is that when a person gets the basics resolved, the rest truly becomes child's play. Sincerely, if you have the mast installed and leveled, the motor out of the box and attached to the mast, the dish attached to the motor stem (tube) and the portable TV and receiver right there with you, it should take 5 - 10 minutes for you to align and track the entire arc, barring one or two oddball sats.

Walrus and I have been setting up FTA dishes for quite a while now. At first, it wasn't this easy. But, now it is really simple and quick.

What takes the most time is the preperations...

1] Select the band and satellites that you are going to receive.

2] Select the dish, LNBF, switches, receiver, motor and mast hardware that
you are going to use for the installation.

3] Install the mast and level it and wait for the concrete to set.

4] Determine your true south satellite.

5] Determine your angles.

6] Set your angles in roughly.

7] Find a signal from your due south satellite.

8] Peak the signal quality for that sat.

9] Pan east and west and peak the signal quality for all sats.

10] Adjust and tweak as required.

11] Enjoy your creation!

Next time you set in a dish, it will be much faster. Once you have a strategy and timeline outlined, it just breezes along. It will become much more simple than you imagine. Getting the basics down first is key and having a methodical setup approach is necessary - i.e. a step by step set of instructions that you always follow.

Trust me, it becomes so much easire if you plan your entire set up from the start to the finish. Don't just go outside and say that you are going to install a dish today, plan it!

RADAR
 

B.J.

SatelliteGuys Pro
Oct 15, 2008
2,029
1
Western Maine
Here is the myth: Once you set the motor lattitude, don't ever change it.
I don't agree at all. I set mine, and never changed it until I had to take the motor apart to re-seat the coax connector.
Here is the reason why this is a myth: You have to set it correctly the first time!

How do you overcome this so that you set it correctly the first time?
Well sure, but this is hardly a reason to say it's a myth that you can't set the motor elevation then never touch it again. I think the number one reason that some people get frustrated with aligning a sat dish is that they can't resist the temptation to keep going back and re-adjust the motor elevation. This almost always makes things worse.
First of all, you need to understand that the motor elevation the motor latitude angles add up to 90 degrees. Ok, that is simple.

Now, you have to know that your motor latitude must be set to the same degree as your site latitude coordinate. If you live at 87.4 W longitude / 42.5 N latitude, then you must set your motor latitude to 42.5 degrees.

Now, why is this a problem for so many people? It is because of two items...

1] The mast or post that the motor is attached / mounted to is not plumb. This screws all angles period! You simply cannot start with this condition. Reset the mast properly to correct this problem.
You *CAN* align a dish with a sloping mast, but yes, it makes things MUCH more difficult.
2] The angle markers on the motor bracket are not refined or precise enough to determine if you are truly set at 42.5 degrees latitude. You may be at 42.3 or 42.6 or 42.7 degrees. How will you judge this accurately so that you know you are right on the mark?

Ok, what needs to be done in the case of item #2 is to remove the dish and motor tube from the motor. Then, slap a inclinometer (a good quality one) on the belly of the motor and read out the degree shown. This is going to be the motor ELEVATION! Now, remember that I said that elevation + latitude = 90 degrees. You want to set the motor LATITUDE to your site's LATITUDE.

However, the inclinometer is reading motor ELEVATION. Therefore, you must subract that from 90 degrees to know the latitude angle that you are setting the motor to.
Every inclinometer I've seen will read either in the latitude scale or elevation scale, depending upon which surface of the usually square inclinometer you put against the motor. What I usually do, is put the inclinometer up to the surface you're going to use for your measurement, then tilt the inclinometer down toward the southern horizon. if the readings go down, then you're measuring elevation. If the readings go up, then you're measuring latitude. But yeah, if you only have an inclination indication, such as with a digital level, then yes, you'll need to subtract from 90.
In this scenario or example, we want the motor latitude to be 42.5 degrees. So, set the motor ELEVATION as read from the inclinometer to read 47.5 degrees and you will then be correct. 90 - 42.5 = 47.5.

Now, when you have this latitude angle set, you will know that it is correct and NOW you do not move it (ever).
Now this is where I really disagree. If you've done this, your dish will NEVER be able to track the arc. You cannot track the arc if you have your motor latitude set to your latitude or elevation set to 90 minus latitude. The "*right* angle to set it to is an angle approximately 0.6 more than your latitude (or subtract 0.6 from elevation). I have a calculator that gives a close approximation to the angle you should use at BJDISCALC2 , however for most purposes the 0.6 adjustment will be OK. As mentioned several times, the reason for this 0.6 is that to see the sats, you also have to set the declination via the dish elevation, and the declination will be more for sats to your south than it is for sats to your east or west by approximately this 0.6 deg amount. The only way to deal with this is to use the declination of an extreme east/west sat, but this will require you to then alter the latitude setting in order to properly track sats to your south.
The biggest problem with this is that it is hard to judge if you are attaching the inclinometer on the motor belly properly to get an accurate reading. You cannot really do this with the dish reflector attached nor with the motor tube attached. This is a preliminary step that must be done prior to attaching those components.
Yeah, this is true. There usually isn't enough room to get most inclinometers in there once you have the dish attached. In some cases you can put a straight edge or a small carpenter's square on the surface to be measured, and put the inclinomer on that, but since you'll never need to touch this again, it's really best to do it before putting the dish on.
The inclinometer must set fully flush and parallel to the flat bottom of the motor housing. Motors may vary in style and make this more difficult if they have raised areas on the belly of the motor. Keep this in mind and apply the inclinometer as needed to read the accurate motor elevation. The seam along the side of the motor where the upper and lower shells of the motor housing meet is an excellent leveling marker, if you can figure out how to utilize it.

A highly accurate inclinometer will allow you to get the motor latitude set correctly if you do it right.

Once this is accomplished, then DO NOT CHANGE IT EVER.
I agree, but why do you call it a myth in your first sentence then proceed to discuss a method that will absolutely require to change the setting or be off by 0.6 deg?

Anyway, we all tend to tell people to set the latitude setting to your latitude, just because it is easier to explain that way, plus for many people, being off by 0.6 deg will be close enough. The problem is, that if someone sets the motor to their latitude, you WILL eventually need to change this. However I really think that if people would start off by using the so called "modified declination", which also requires a "modified latitude" setting, then it is really true that you won't ever have to touch that adjustment again, unless your pole moves or something.

One other thing though. The above applies mainly to small offset dishes, because the motor elevation is more accurately set than the declination, so that setting the motor elevation can be done, then the declination (dish elevation) can be used to fine adjust the alignment. With some prime focus dishes, it is often more accurate to set the declination first, and then never touch THAT again, and do the fine adjustment via the latitude setting. It's just a question of which of the two settings can be done most accurately or most easily.
 

AcWxRadar

Thread Starter
SatelliteGuys Pro
Apr 26, 2006
4,575
4
40 miles NW of Omaha. Omaha?
I don't agree at all. I set mine, and never changed it until I had to take the motor apart to re-seat the coax connector.

Well, now that is obviously a different circumstance altogether.

Well sure, but this is hardly a reason to say it's a myth that you can't set the motor elevation then never touch it again. I think the number one reason that some people get frustrated with aligning a sat dish is that they can't resist the temptation to keep going back and re-adjust the motor elevation. This almost always makes things worse.

This is exactly what I mean to express. Adjusting the motor latitude should not be a temptation while tweaking and fine adjusting the arc. If it is set properly right from the start, it should remain there. I am using the term "myth" rather loosely, but that is in order to make the point.

You *CAN* align a dish with a sloping mast, but yes, it makes things MUCH more difficult.

Oh, yes! This wouldn't be too bad if you were setting up a fixed point dish. You could compensate for this without too much trouble. But, with a motorized dish? Uh uh!

Every inclinometer I've seen will read either in the latitude scale or elevation scale, depending upon which surface of the usually square inclinometer you put against the motor. What I usually do, is put the inclinometer up to the surface you're going to use for your measurement, then tilt the inclinometer down toward the southern horizon. if the readings go down, then you're measuring elevation. If the readings go up, then you're measuring latitude. But yeah, if you only have an inclination indication, such as with a digital level, then yes, you'll need to subtract from 90.

The inclinometers that you can buy from Menards or most any hardware store like I use (if placed against the flat belly of the motor) always read out the angle of the ELEVATION. Since the motor stem extends at a right angle or 90 degrees from this surface, the angle of the motor stem is what needs to be set to the same angle as the latitude. On my SG-2100 and DG-XXX series motors, the belly of the motor is the most true and flat surface to take the elevation reading.

Now this is where I really disagree. If you've done this, your dish will NEVER be able to track the arc. You cannot track the arc if you have your motor latitude set to your latitude or elevation set to 90 minus latitude. The "*right* angle to set it to is an angle approximately 0.6 more than your latitude (or subtract 0.6 from elevation). I have a calculator that gives a close approximation to the angle you should use at BJDISCALC2 , however for most purposes the 0.6 adjustment will be OK. As mentioned several times, the reason for this 0.6 is that to see the sats, you also have to set the declination via the dish elevation, and the declination will be more for sats to your south than it is for sats to your east or west by approximately this 0.6 deg amount. The only way to deal with this is to use the declination of an extreme east/west sat, but this will require you to then alter the latitude setting in order to properly track sats to your south.

I have considered your notion regarding this compensation of 0.6 degrees. However, I had not utilized this when I first set up my motor and dish as I was unaware of this at the time. I just set the motor to the precise latitude degree of the site and all was well - I did not have to make any compensations when aligning to the arc and I am able to cover an arc of 118 degrees spot on for every satellite. But, I promise to incorporate it during my next dish installation to see how everything works out. If it improves results for me, I will apply this.

Yeah, this is true. There usually isn't enough room to get most inclinometers in there once you have the dish attached. In some cases you can put a straight edge or a small carpenter's square on the surface to be measured, and put the inclinomer on that, but since you'll never need to touch this again, it's really best to do it before putting the dish on.

Exactly.

I agree, but why do you call it a myth in your first sentence then proceed to discuss a method that will absolutely require to change the setting or be off by 0.6 deg?.

Well, I guess I was using the term a bit loosely. It is not a myth, but rather a taboo. As you also have stated, it is that temptation to dabble with this angle setting when a person is not achieving the desired results right off. And, as you say, it just compounds their misery.

Anyway, we all tend to tell people to set the latitude setting to your latitude, just because it is easier to explain that way, plus for many people, being off by 0.6 deg will be close enough. The problem is, that if someone sets the motor to their latitude, you WILL eventually need to change this. However I really think that if people would start off by using the so called "modified declination", which also requires a "modified latitude" setting, then it is really true that you won't ever have to touch that adjustment again, unless your pole moves or something..

You are likely quite correct, but as you also say, that 0.6 degree compensation may not be entirely necessary - it will likely be close enough for most. And, it indeed is easier to explain when you are communicating the way we are - i.e. using the web and a forum where you are not directly speaking face to face with the person you are helping.

One other thing though. The above applies mainly to small offset dishes, because the motor elevation is more accurately set than the declination, so that setting the motor elevation can be done, then the declination (dish elevation) can be used to fine adjust the alignment. With some prime focus dishes, it is often more accurate to set the declination first, and then never touch THAT again, and do the fine adjustment via the latitude setting. It's just a question of which of the two settings can be done most accurately or most easily.

Yes. I was directing the overall scope of the discussion to an offset, smaller Ku band dish and not a prime focus dish.


B.J.

You have really picked my theory and information to the bare bones! :) However, your arguments seem to help support it (except for your addition of the modified declination) which is something very beneficial to consider here.

The main point I was trying to infer is to get the latitude setting correct right off the bat and then never alter it. Many people were, as you say, getting frustrated and wanting to adjust this later to compensate for some other error that they could not identify. This of course leads to a big mess and more frustrations. It is the WRONG direction for them to go.

When I set up my first motor, I was a bit like that, too. It bothered me that there was so much space in between the degree markings on both the motor bracket and the dish assembly and I thought to myself that this would leave a huge margin for error. So, using a very sensitive and accurate inclinometer and bubble level, I set out to determine a more refined approach (measurement).

In other words, the motor latitude adjustment should not be considered as a variable. Just the same as having the mast plumb. These should both be constants and then you will be left with just barely two variables. The azimuth alignment and the dish elevation. The dish elevation (I have found) is less than a variable, too. If everything else is set correctly, then this too will be so doggone close to what is calculated that it is unreal. But, alas - the angle markings on the dish are vague and leave the exact adjustment angle up to interpretation.

RADAR
 
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hd fan

SatelliteGuys Pro
Jan 1, 2009
754
0
Ontario
BJ, What about the Stab motor? It does not have a declination setting therefore as per STAB and the motor documentation the Elevation should be set to your exact Latitude (no 0.6 degree difference). The scale on the motor has 0.1 degree tolerance or error margin. I have always set the ones I have installed to the exact Latitude 43.X (I do not travel far , lol)

**** The tolerance is acctually 1 degree, so I can only set it half way between 43 and 44. ****
 
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B.J.

SatelliteGuys Pro
Oct 15, 2008
2,029
1
Western Maine
BJ, What about the Stab motor? It does not have a declination setting therefore as per STAB and the motor documentation the Elevation should be set to your exact Latitude (no 0.6 degree difference). The scale on the motor has 0.1 degree tolerance or error margin. I have always set the ones I have installed to the exact Latitude 43.X (I do not travel far , lol)

Re Stab motor & declination... You don't really set the declination with the motor, you set declination via the dish elevation. However different motors have a different angle of bend in the motor shaft, which is a preset declination MUCH more than you need, that allows you to set a negative declination by adding a positive dish elevation (ie if your declination is 5 degrees, and the bend in the shaft is 30, then you use 25 deg to get 25-30=-5.... if that makes sense.

Re the motor directions telling you to use your latitude, yeah, that's what bothers me, because their manuals are simply wrong. I think they do that just because it's easier, and the 0.6 deg won't make any difference to many people. However what I've seen in forums like this, is that when someone's latitude is say 40.4, they will round off to 40, which puts them even further away, ie a whole degree. Then I see people using these complicated methods of going to the extremes, and seeing if lifting up or pulling down improves or makes it better, then altering the declination, which results in you having to change the latitude adjustment...... or people just see that they can get some improvement when they used the exact latitude, and start changing things randomly, and end up making things worse.
My whole point was, that if you make a good effort to set the latitude adjustment right in the first place, and best if that right is the modified numbers, then I agree with Radar's statement that you set it and never touch it again. For many cases, particularly with smaller dishes, you may not notice any difference due to being off 0.6 deg.
 

SatelliteAV

SatelliteGuys Master
Lifetime Supporter
Sep 3, 2004
6,486
183
Roseville, CA
It is so great to see the effort being put into creating a base of information for motor installs!

If only the scale readings and mechanical tolerances of a HH motor were within a fraction of a degree! :D The tolerances of the HH motor samples usually is nowhere near a single degree. This discussion is dealing with theory and not a typical installation reality.

Having installed hundreds of HH motors over the years, I stick with the perfectly plum and level post, set the motor angle using the Latitude scale, set the dish elevation angle as per the table provided with the motor. Once the Latitude adjustment is correct and set, lock 'er down...... If the post is not loose or sloppy, the tracking will usually be fine tuned with slight adjustments to the dish elevation setting.

:rant: (Climbing onto soapbox in the busy city center, Brian clears his throat and begins to speak......) "Who cares what satellite is true South?" :eek: The process of fixating a newbie on the reception of his True South satellite and aiming for that satellite before anything else is the downfall of many a new installation. It just isn't necessary to locate and lock onto the true south satellite. I know that this will ruffle some feathers, but USALS has changed the way that HH motorized dishes can be installed

Using USALS, drive the motor to an active and appropriate satellite with the receiver placed on an active transponder in the southern sky will result in a successful install. I usually start with any satellite orbital position that is close to the installation Longitude, but that isn't necessary. There is the old school way of trial and error in driving the motor to an approximate heading while correlating the azimuth and declination settings, then there is the USALS method. Both will work, but USALS takes the much of the "geek factor" out of installing the motor!

There is an easy way to install a motorized dish then there is the process using protractors, slide rules, Texas Instrument scientific calculators, reverse calculations, degrees per scale mark, angle finders on every conceivable part of the dish or motor with angle calculations appropriate and applicable to each.

We offered a HH motor install demo to a dozen SatelliteGuys members attending an installation workshop a few years ago and demonstrated that the dish could be put on the arc in less than 30 minutes. It takes more time to Blind Scan the arc of satellites than it does to install the HH motor!

We all have our way of installing gear.... I love the fact that we have a sticky thread dedicated to motor installations!!!
 

hd fan

SatelliteGuys Pro
Jan 1, 2009
754
0
Ontario
I might just set a temporary dish with a motor and spend some time just to test the accuracy of the 0.6 degrees statement. I am not saying you are not right in terms that there is 0.6 degree factor to consider with other motors (specially the ones that requiere a declination setting), I am just saying that at least with Stab , so far , I have set the Latitude dead on and it works beautifully. I am assuming that when they built their motors they take into consideration this and therefore the scale is mark accordingly.

My problem with your argument is that depending on the motor brand then it might not be the optimal setting for someone using a Stab motor.

This is all speculation of course, I might send an email to Stab asking for clarification on the matter.

BTW out of memory in my last post I made a mistake on the Stab motor Elevation scale tolerance. I said it was 0.1 degree and this is incorrect. It is acctually 1 degree.

My latitude is 43.6 and therefore I always set it halfway between 43 and 44 but to be statistically precise other than 43 or 44 degrees the motor has no accuracy on its scale to guarantee any other value.

In any case this is very interesting information you have given. At least when there is no good programming there is another reason to play with the motorised set up, lol.
 

B.J.

SatelliteGuys Pro
Oct 15, 2008
2,029
1
Western Maine
.... I am not saying you are not right in terms that there is 0.6 degree factor to consider with other motors (specially the ones that requiere a declination setting), I am just saying that at least with Stab , so far , I have set the Latitude dead on and it works beautifully. I am assuming that when they built their motors they take into consideration this and therefore the scale is mark accordingly.
I don't think it's possible that motors take this into consideration, because it isn't always 0.6 degrees. It's different depending upon your latitude. I've made a chart here (I don't guarantee the accuracy but it should be close):
45 0.69
40 0.69
35 0.66
30 0.61
25 0.54
20 0.46
15 0.36
10 0.25
5 0.13
0 0.00

Since most on the forum are in the US, I just call it 0.6 as an approximation. But unless the motor manufacturers sell motors that are designed for different latitudes, then they cannot be taking this effect into consideration. They SHOULD be giving you a chart, such as the "modified" chart at the geo-orbit page (Footprints by Dish Size - Latitude Declination Chart - C/Ku-Band Satellite Listing) . If you look at that chart, you will see that for each latitude they have a column that they call "elevation angle" (but really this is 90 minus elevation, ie the latitude angle). You'll see that for each latitude, the "elevation angle" is slightly more than the actual latitude, similar to adding the 0.6 factor to the latitude in my chart above. So you see, the motor scale really CANNOT take this into consideration. To take it into consideration, you have to put the scale on a setting a bit more than your latitude.

And there is absolutely no question that this "0.6 factor" is real. Basically this 0.6 (or the angle off the chart above) is the difference between the declination for a sat to your south vs the declination of a sat to your east or west. Declination is dependent on your latitude. Ie someone on the equator doesn't use ANY declination, and the further north you are, the more you have to add declination to look down to the equatorial plane. Declination is simply the angle who's tangent is your distance above the equatorial plane divided by your distance to the sat. Your distance above the equator is constant, and depends on your latitude, however the distance to the sat is different for each sat. Sats to your south are closer to you. Sats to your east or west are further away, so the declination will be smaller.
The motor manuals usually simplify things by telling you to set your motor elevation at 90 minus your latitude, ie setting your latitude on the latitude scale, however doing this means that when you peak on your south sat using dish elevation, you'll be setting your declination to the declination of your south sat, and you will by definition be off by the 0.6 angle (off the chart) for your latitude when you aim at a sat to your extreme east or west. The ONLY way to compensate for this effect is to instead use the modified declination/modified latitude setting, which basically uses the declination of a sat to your east/west and compensates for sats to your south by decreasing the elevation (increasing latitude setting) by the 0.6 degree factor. This factor is essentially pro-rated across the arc because elevation adjustments have no effect on sats to your east or west, and proportionally more effect the closer you get to south.
My problem with your argument is that depending on the motor brand then it might not be the optimal setting for someone using a Stab motor.
You need to take this into consideration with all mounts, whether small H-H motors or big C-band mounts. And as mentioned above, it cannot be taken into consideration by the manufacturer shifting the latitude scale, unless they sold different motors or mounts for different latitudes, which they don't. But if you are un-sure about what the motor scale really means, then you shoud use an inclinometer to set the motor instead of trusting the scale. Then there would be no question.
This is all speculation of course, I might send an email to Stab asking for clarification on the matter.
I'd be interested in what they say. THey're obviously giving you a chart which is just an approximation, and they just assume that most people won't notice the error.
BTW out of memory in my last post I made a mistake on the Stab motor Elevation scale tolerance. I said it was 0.1 degree and this is incorrect. It is acctually 1 degree.
Right. And it's obviously pretty hard to set this angle to accuracies smaller than 1 degree, and for most dish/receiver combinations, you can't tell the difference with errors that small. With bigger dishes, such as with a good 10' dish doing Ku, you can easily see the effect. I think that these motor manufacturers just tell you to use your latitude because it's easier, and the resolution of a 30" dish on Ku is so wide that you can't tell the difference when you're off by 0.6 degrees. But the bigger the dish or the the higher the frequency, the more important this factor becomes.
My latitude is 43.6 and therefore I always set it halfway between 43 and 44 but to be statistically precise other than 43 or 44 degrees the motor has no accuracy on its scale to guarantee any other value.
.

The situation when this factor becomes more important would be for people who say are at 43.4. I've seen posts from people who say that they just rounded 43.4 off to 43, when in fact the acual number they should be using would be 44. Ie by rounding off, they're increasing the error up to a whole degree. In your case, by splitting the difference and only off by about 0.7-0.8 degrees, and if you had rounded off to 44, you would have been closer. Basically, I realize that you really can't set these motors very accurately via the scales, but it helps if you at least start out trying to set the proper value, instead of a value that is off by the better portion of a degree.
 

AcWxRadar

Thread Starter
SatelliteGuys Pro
Apr 26, 2006
4,575
4
40 miles NW of Omaha. Omaha?
It is so great to see the effort being put into creating a base of information for motor installs!

If only the scale readings and mechanical tolerances of a HH motor were within a fraction of a degree! :D The tolerances of the HH motor samples usually is nowhere near a single degree. This discussion is dealing with theory and not a typical installation reality.

Having installed hundreds of HH motors over the years, I stick with the perfectly plum and level post, set the motor angle using the Latitude scale, set the dish elevation angle as per the table provided with the motor. Once the Latitude adjustment is correct and set, lock 'er down...... If the post is not loose or sloppy, the tracking will usually be fine tuned with slight adjustments to the dish elevation setting.

:rant: (Climbing onto soapbox in the busy city center, Brian clears his throat and begins to speak......) "Who cares what satellite is true South?" :eek: The process of fixating a newbie on the reception of his True South satellite and aiming for that satellite before anything else is the downfall of many a new installation. It just isn't necessary to locate and lock onto the true south satellite. I know that this will ruffle some feathers, but USALS has changed the way that HH motorized dishes can be installed

Using USALS, drive the motor to an active and appropriate satellite with the receiver placed on an active transponder in the southern sky will result in a successful install. I usually start with any satellite orbital position that is close to the installation Longitude, but that isn't necessary. There is the old school way of trial and error in driving the motor to an approximate heading while correlating the azimuth and declination settings, then there is the USALS method. Both will work, but USALS takes the much of the "geek factor" out of installing the motor!

There is an easy way to install a motorized dish then there is the process using protractors, slide rules, Texas Instrument scientific calculators, reverse calculations, degrees per scale mark, angle finders on every conceivable part of the dish or motor with angle calculations appropriate and applicable to each.

We offered a HH motor install demo to a dozen SatelliteGuys members attending an installation workshop a few years ago and demonstrated that the dish could be put on the arc in less than 30 minutes. It takes more time to Blind Scan the arc of satellites than it does to install the HH motor!

We all have our way of installing gear.... I love the fact that we have a sticky thread dedicated to motor installations!!!

Brian,

Excellent explanation and description that you have relayed here. I agree with your analysis and I have proven that your time estimate to align to the arc is easily accomplished. This is providing that you are not including setting up the mast, concreting it in and counting the time to haul all the equipment around to prepare to get underway.

If you don't count all this time, you can truly align to the arc in less than 30 minutes for certain. 7-15 minutes if you really try hard and have a set pattern to follow. Knowing the satellites and transponders which are strong and active in the location where you are setting up the dish is key. That allows you to use data and information from memory and not have to look up tables and calculate angles and all that matter.

Every bit of information and advice we share here, can only improve our setups and reduce our set-up time. So, we are definitely doing a good thing to discuss and post new ideas and information.

RADAR
 

hd fan

SatelliteGuys Pro
Jan 1, 2009
754
0
Ontario
Thanks so much BJ for all the valuable info. I will defineatelly be using this adjustment in future Stab motors installations. Sometimes being Stubborn has its merits, lol.
 

JohninSD

SatelliteGuys Family
Nov 7, 2009
79
1
San Diego
Electronic Inclinometer on sale

Stumbled on this thread and it inspired me to check the latitude setting on my setup. I used an electronic inclinometer I bought recently from Rockler for $30 on sale. It's for use in my shop but it works well for this too. It's supposed to be accurate to .1 degree and a quick check bears that out. I used a 6" steel machinist's square on the motor base and read the elevation off that. According to the Latitude + Elevation +0.6 formula I'm off about .15 degree - think I'll leave it alone. Right now I'm getting sats from 83W to 129W, though some of them are low Q - I'll do a little dish tweaking once I rig up a fine adjustment scheme for the dish elevation - just loosening the bolts and moving it in small increments is too iffy for me - sometimes it jumps right past where I wanted it and sometimes it won't move at all - also pushing on it flexes things a little and it's too hard to guess how far to go. Whew that was a long sentence.

John
 

SATisfied

SatelliteGuys Pro
Feb 22, 2006
286
0
Lineboro, MD
Excellent read, guys....I used the Sadoun website on setting up my motorised dish, but this thread has really been an education. Thanks for taking the time to share your knowledge (everyone)....much appreciated.
 
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