Azimuth Question??

[Greg Mueller]

I guess the part that bothers me is the way the building inspector said that the readings were not repeatable in his review. Put it on once and it says one thing and the next time it says something else (according to him). Since he tried to use it professionally and couldn't, it turns on a little warning light for me

 

[N6BY]

I guess the part that bothers me is the way the building inspector said that the readings were not repeatable in his review. Put it on once and it says one thing and the next time it says something else (according to him). Since he tried to use it professionally and couldn't, it turns on a little warning light for me

The state inspector said " it never matches the reading of my original smart level and I just don't trust it". It depends on how close of a match he expects. Maybe he's got some gunk on the bottom of one of the levels. Even the smallest amount would affect it greatly.

1/10th of a degree is exceedingly small. On a 10 inch level, 0.1 degree is 0.017 inch difference from end to end. The calculation for this is as follows: 10*tan(0.1) = 0.017 or about 1/60th of an inch. In a construction environment, I can see how the slightest bump on a piece of lumber or a patch of concrete would give a different reading.

Since I use my LaserTrac level on smooth metal surfaces (satellite dishes and poles), I get the +- 0.1 degree accruacy.

 

[Greg Mueller]

Ok whatever
By the way I've been a machinist for 25 years and am used to dealing with small angles and measurements.
I own CNC machines and use Cadcam software.
Repeatability is a bench mark of accuracy in my world. If you are happy with your Craftsman level more power to you. I wouldn't have Craftsman anything in my shop.
To each his own.

 

[N6BY]

... I wouldn't have Craftsman anything in my shop. ...

That's fine, and I'm happy that you have alternative tool companies.

But I try not to criticize things that I have never tried using personally.

 

[Greg Mueller]

Good

 

[deaner]

To understand remarks you must understand people and products. Check with older people on sears products in the past and it is very enlightening. Sears has come a very long ways and now has a much better product Than it had for many years. We all need to try to be better understanding of others and what they say. This includes myself. Many times a statement is a statement and nothing is meant to offend. Just my two cents worth.

 

[Greg Mueller]

I guess the mistake I made was thinking that there was a quest for knowledge going on on this BB. Speaking only for myself, I am eager to listen to what a professional in any given field, with decades of experience, has to say concerning their field of expertise. But then, I like to learn things. It seems what I have accomplished is bruising egos instead of education. For that I apologize and promise to never give a professional opinion or impart the least amount of my accumulated knowledge ever again on this BB.

Good day

 

[N6BY]

...For that I apologize and promise to never give a professional opinion or impart the least amount of my accumulated knowledge ever again on this BB.

Good day

We're just talking about a laser level -- no one was trying to offend anyone here. I acknowledge that you are a professional machinist with decades of experience.

All I was saying was that it works great for me. And if you haven't tried it yourself then you cannot possible give a useful evaluation of it.

 

[N6BY]

...For that I apologize and promise to never give a professional opinion or impart the least amount of my accumulated knowledge ever again on this BB.

Good day

We're just talking about a laser level -- no one was trying to offend anyone here. I acknowledge that you are a professional machinist with decades of experience.

All I was saying was that it works great for me. And if you haven't tried it yourself then you cannot possibly give a useful evaluation of it.

 

[B.J.]

BTW, I received the Sears level yesterday, and had a chance to play around with it today, and so far I really like it, and think it's a great value for the price.

I generated some angles using the laser aimed at a wall 10' away from the back of the level, and measured how much higher up the wall the laser spot hit when the front of the level was raised, then compared the indicated angle to the angle calculated from the tangent obtained by the measurements.

In the few experimental measurements I tried, the level seems to be repeatable AND accurate to the +/- 0.1 deg specs. All calculated angles, when rounded off to 0.1 hit the indicated angle right on. (I didn't use the zero function, but rather subtracted my zero indication from the measured angle.) And 0.1 deg is more than accurate enough for 99% of TVRO'ers, mainly because unless you have a really big dish, none of us can observe any difference caused by a 0.1 deg difference in aim, plus there are other innaccuracies involved in a typical consumer satellite dish that are much greater than the accuracy specs of this level.

I'm sure that there are applications which need greater precision and accuracy, and a more expensive device is probably a better value for someone who needs more accurate measurements, but if the level is being purchased for TVRO or home shop use, I think this is a good value.

 

[N6BY]

B.J.,

Glad to hear yours arrived and that you like it. I think its great for satellite dish elevation measurement (and many other uses).

In using mine I noticed one small thing to watch out for -- if you set the level on soil, the magnet might pick up iron particles that could affect the flatness of the level. Its no big deal if you can remember to brush them off. But I'm really glad it does have a magnetic bottom -- its strong and it sticks to the metal sat dish while adjusting the elevation.

I've got a 10' motorized BUD and right now it picks up all the FTA channels on the C/KU arc from 72W to 135W. (I'm at 121W). I think the azimuth adjustment is very slightly off and it affects the western side of my dish's arc the most.

The problem I'm having is getting the dish pointed perfectly south when it is at the peak of its arc. I can easily adjust the dish to pick up 121W (my true south satellite), but when I do that I can't tell if my dish is at its highest angle. Even the 0.1 degree accuracy is not enough to determine the precise peak for my dish. Any ideas how I can do this?

 

[B.J.]

The problem I'm having is getting the dish pointed perfectly south when it is at the peak of its arc. I can easily adjust the dish to pick up 121W (my true south satellite), but when I do that I can't tell if my dish is at its highest angle. Even the 0.1 degree accuracy is not enough to determine the precise peak for my dish. Any ideas how I can do this?

My first thought was that this wasn't that critical. I've always just eye-balled this, but you started me thinking, and I've started thinking that it could depend on what kind of mount you have.

On some mounts, there are surfaces that would be vertical or horizontal when at the top of the arc, and it shouldn't be too hard to figure out. You might be able to use the laser and create lines parallel to the aim on each side of mount, and see if they tracks back to the pole. I really think that if you set your elevation to 0.1 deg, you'd be fine, and you can set the declination by peaking while even being off by a degree or so of being at the top of the arc, I doubt that you could tell any difference.

However it isn't so clear what to do on MY mount, which is one of those Orbitron Spinclination things. Ie, when the mount itself is at the top of it's arc, the dish itself is aiming several degrees to the west of due south, and when the dish is aiming due south, the mount is not at it's highest point, so the question is, with a spinclination mount, do you peak on your true south sat (when not at the highest point of the mount), or do you have the mount at it's highest point, and peak on a sat to the west of your true south? This never really occurred to me in the past, but I think that I luckily did the right thing. Ie with the spinclination, I can set the declination pretty accurately, but then I set the elevation of the rotation axis by peaking on a sat. When I first set up my dish, there wasn't a sat due south of me, so I peaked on a sat that was a couple degrees west of my due south, which I think was what I should have done. Later on, there WAS a sat due south of me, but there was a tree in the way, so I still used the sat a few deg west. Recently though, I cut that tree down, and for the past year, I've been peaking on my true south sat, and my alignment hasn't been quite as good since. You may have got me realizing why that is.

Since I'm setting declination via spinclination, and peaking to set the elevation of the rotation axis, I think when it warms up a bit, I'm going to take this new level out there and see how close to the proper elevation I am. However the fact that the dish itself might not be aiming perpindicular to it's mount connections, or the feedhorn might not be centered, etc, even with 0.1 deg accuracy, I think that the level might be OK for setting the axis elevation, but shouldn't be used for declination. If my elevation is off, I'm thinking that I should reconsider relying upon the spinclination for declination.

Anyway, having this 0.1 deg accuracy creates a lot of things to think about that I hadn't considered before. My brain is starting to get tired thinking about that spinclination aiming west of due south while at top of arc. Interesting.

But for non-spinclination mounts, I don't think there is much of a problem.

 

[N6BY]

I found a link to a discussion on this forum about the Orbitron Spinclination mount and adjustment. Its at http://www.satelliteguys.us/c-band-satellite-discussion/160988-orbitron-spin-o-something.html That might help you. I guess they designed it so they would not need a separate declination adjustment.

Mine has a conventional polar mount with a separate declination adjustment. I've got it set for 6.1 degrees declination, which should be correct for my 38.8 degree latitude.

All the satellites east of 121W degrees are aligned perfectly. However, satellites 137W and farther west do not have enough signal quality to receive.

I think I need to determine if the dish is too high or too low for the western side of the arc. If my dish is too high I need to move it east and lower the elevation, and if its too low I need to go west and raise the elevation.

Getting every satellite on the arc seems like no minor achievement! Especially if you can get all the KU sats.

 

[B.J.]

I found a link to a discussion on this forum about the Orbitron Spinclination mount and adjustment. Its at http://www.satelliteguys.us/c-band-satellite-discussion/160988-orbitron-spin-o-something.html That might help you. I guess they designed it so they would not need a separate declination adjustment.

The spinclination allows you to set declination very accurately, probably as accurate as the 0.1 deg you get with the level. I set my declination about 13 years ago, and haven't touched it since. However it complicates other aspects of the alignment.

Mine has a conventional polar mount with a separate declination adjustment. I've got it set for 6.1 degrees declination, which should be correct for my 38.8 degree latitude.

All the satellites east of 121W degrees are aligned perfectly. However, satellites 137W and farther west do not have enough signal quality to receive.

Using that 6.1 deg declination, you'll be off as much as 0.6 deg on some sats. You are much better off using the so called "modified" declination, ie ~5.45 for your latitude. See:
Footprints by Dish Size - Latitude Declination Chart - C/Ku-Band Satellite Listing
and
BJDISCALC2

I think I need to determine if the dish is too high or too low for the western side of the arc. If my dish is too high I need to move it east and lower the elevation, and if its too low I need to go west and raise the elevation.

Getting every satellite on the arc seems like no minor achievement! Especially if you can get all the KU sats.

If you use the proper declination, and elevation and get the elevation via tuning on your south sat, or by using the modified angles with your level, then usually all you need to do is go to your far western or eastern sat, and peak that by rotating the whole mount on the pole very slightly, peaking with the motor after each adjustment to see if you've made it better or worse. Basically a 2 step process, and you should be within 0.1 deg across the arc if everything goes well.

 

[Greg Mueller]

Once you have the declination angle set and the dish at is highest point on the axis mount, you should aim it due south by peaking it on 123W.

After you have it peaked for 123W, you can move the actuator and see if some of the satellites to the east and west are properly tracked. It took some trial and error for me to get mine to track the entire arc.

Without the 0.1 degree accuracy of the Craftsman Level, I would probably never have been able to align my dish to the satellite arc.

I found a link to a discussion on this forum about the Orbitron Spinclination mount and adjustment. Its at http://www.satelliteguys.us/c-band-satellite-discussion/160988-orbitron-spin-o-something.html
All the satellites east of 121W degrees are aligned perfectly. However, satellites 137W and farther west do not have enough signal quality to receive.

I think I need to determine if the dish is too high or too low for the western side of the arc. If my dish is too high I need to move it east and lower the elevation, and if its too low I need to go west and raise the elevation.

Getting every satellite on the arc seems like no minor achievement! Especially if you can get all the KU sats.

Priceless.......:clap

 

[N6BY]

Using that 6.1 deg declination, you'll be off as much as 0.6 deg on some sats. You are much better off using the so called "modified" declination, ie ~5.45 for your latitude. See:
Footprints by Dish Size - Latitude Declination Chart - C/Ku-Band Satellite Listing
and
BJDISCALC2

I am using a declination of 6.1 which is according to the formula (table 1). Also, the declination table at Sadoun http://www.sadoun.com/Sat/Installation/DECLINATION-ANGLE-TABLE.htm makes no mention of the modified values -- it uses the calculated values. Anyway, I'm really not sure which table (calculated or modified) is correct for my dish. My best guess is that the 'modified' declination table is for dishes/mounts that sag down at the ends of the arc due to a weak mount or slightly loose bolts. This will require experimentation.

I had my dish tracking the entire arc last week for C-band.

KU band has been more difficult. Yesterday I had all KU except for the western end. Today I finally tweaked it to get the entire KU band arc. There's much less room for error in KU band.

B.J., did you get your Spinclination setup tracking everything?

 

[Lak7]

Today I finally tweaked it to get the entire KU band arc. There's much less room for error in KU band.

Nice job!
To me at least, Ku on a BUD has no room for error.

My best guess is that the 'modified' declination table is for dishes/mounts that sag down at the ends of the arc due to a weak mount or slightly loose bolts.

No, dish must be secure.

Modified Polar angle chart expalined:

However, upon
practice, it has been discovered that using the latitude as the
elevation angle, (first chart below),
the satellites at the top of the arc, in a tracking mount system,
were in perfect alignment with the satellite dish, i.e. were
tracked perfectly by the polar mount, whereas the satellites
at the lower ends of the arc where not tracking correctly. Conversely,
if the satellites at the ends of the arc, on the horizon, were
tracking correctly then the central satellites, at the top of
the arc would be slightly off target. This effect is caused by
the slight deviation from the true north/south line, caused by
the act of the tilting of the dish, as the dish moves to view
satellites lower on the arc, i.e. closer to the horizon. With
this in mind, it was formulated the elevation/declination angles
of the modified polar mount (second chart
below) whose application has no effect on seeing satellites
at the top of the arc but has the effect of better tracking on
the sides and low end of the arc. This effect is accomplished
by slightly increasing the elevation angle and accordingly slightly
decreasing the declination angle by the same amount.

Footprints by Dish Size - Latitude Declination Chart - C/Ku-Band Satellite Listing

 

[B.J.]

I am using a declination of 6.1 which is according to the formula (table 1). Also, the declination table at Sadoun Declination Angle Table makes no mention of the modified values -- it uses the calculated values. Anyway, I'm really not sure which table (calculated or modified) is correct for my dish. My best guess is that the 'modified' declination table is for dishes/mounts that sag down at the ends of the arc due to a weak mount or slightly loose bolts. This will require experimentation.

The charts and calculators that you mention are based on the declination of a sat to your south. The declination of sats to your east or west will be up to about 0.6 degrees less than that, because they are further away from you. You cannot get accurate tracking using those charts. The modified declinations are based on the declination of sats to your far west or east. Of course you would likewise be off by 0.6 deg in the middle of your arc if you just used that declination too, however what you do is increase your latitude setting (decrease elevation) by that same 0.6 degrees. Notice that the modified chart also shows a latitude setting different from you latitude. This does not affect the aim near the east/west horizons since it's an orthogonal movement, however it allows you to track to within less than 0.1 deg across the arc. Basically the charts at Sadoun, and other places including most dish manuals, are all poor approximations. Using those numbers, you can get close enough for Ku on a 3' dish, or close enough for C-band on a 10' dish, but you can't do Ku on a 10' dish with those numbers. The modified numbers are the correct numbers. What you find on Sadoun and other sites are simply a crude approximation that is good enough for some users, and usually ends up with people tweaking this and that, trying to get it to track. If they do get it tracking, the angles will end up being the modified numbers.

I had my dish tracking the entire arc last week for C-band.

KU band has been more difficult. Yesterday I had all KU except for the western end. Today I finally tweaked it to get the entire KU band arc. There's much less room for error in KU band.

B.J., did you get your Spinclination setup tracking everything?

Yeah, until the trees grew up around me, I was tracking from about 135 in the west, down to somewhere around 30 in the east, which was where the trees got me back then. Now, the trees only allow me to see from around 58-127, with 3 or 4 sats in that range lost to specific trees in the way. Plus my dish is quite dented now due to hitting it with a broom. But it tracked the arc pretty well when it was young and the trees were shorter.

 

[N6BY]

The charts and calculators that you mention are based on the declination of a sat to your south. The declination of sats to your east or west will be up to about 0.6 degrees less than that, because they are further away from you....

Thanks for the explanation. I had thought they were all the same distance from us, but you're right, I did the trigonometry and verified that the sats at the ends of the arc are further away.

Due to my neighbors trees, my arc can go +- 60 degrees from my due south sat. So at 60 degrees from due south, I calculated the sat distance from my lat/long as 25,161 miles. My due south sat distance is less, at 23,475 miles.

The angular difference from these two distances is about 0.4 degree. If I wanted to go horizon to horizon then I would probably need the 0.6 degree angular difference as suggested by the modified table.

Right now I am getting all the satellites, but the ends of the arc are not coming in as strong as the middle. I'll drop the declination from 6 to 5.4 and see what happens.