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Interesting DirecTV aiming issue re Alaska -- my thoroughly basic mistake revealed
This thread has 9 replies. Displaying all posts.
Post 1 made on Sunday January 19, 2014 at 02:26
Ernie Gilman
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edit: it only took ten posts for me to see what someone was trying to say here. Totally basic DUH mistake at the get-go.

original text of this post:

Well, it's interesting to me, anyway.

I've had to provide some DirecTV aiming information for Cordova, Alaska. I found the zip code; looked in my HR24 for the coordinates; found that azimuth is given in compass direction, i.e. re magnetic north (106 degrees, which for DirecTV equals 16 degrees E of due South); converted magnetic north to reference true north; and concluded that the dish should be pointed 3 degrees west of due South.

Any serious boat owners out there? Navigators? The problem is, it occurred to me today, that if one pointed due south from there, one would point to a location in the sky at -145 degrees, while the satellites are, for sake of argument, at -101. (Minus indicates west here.) And three degrees west of due south is NOT closer to 101!

So is this at all possible? One of many reasons I'm not a rocket scientist is that I cannot envision, three dimensionally, tangents to spheres crossing orbit lines. The fact that the sun shines on the north sides of buildings here in CA at 34 degrees N both in the morning and before sunset baffles me enough to wonder if my 3 degrees W of S is possible.

In New York, dishes point west of south. In California, they point east of south. In the middle of the country they point more or less due south. How could being at 63 degrees latitude make the correct azimuth for the dish be the same as some place east of Texas?

Any ideas?


edit: added "re Alaska" to thread title.

Last edited by Ernie Gilman on January 20, 2014 12:46.
A good answer is easier with a clear question giving the make and model of everything.
"The biggest problem in communication is the illusion that it has taken place." -- G. “Bernie” Shaw
Post 2 made on Sunday January 19, 2014 at 09:18
william david design
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[Link: satsig.net]
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Post 3 made on Sunday January 19, 2014 at 11:41
JustinG
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On January 19, 2014 at 09:18, william david design said...
[Link: satsig.net]

Also check out, http://www.dishpointer.com they have a handy smartphone app as well.
Post 4 made on Sunday January 19, 2014 at 12:08
Fins
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We cannot answer this question without all of the details. We need the zip code, the actual model of DTV receivers, and which dish is being used.


How do you expect any correct answer without every detail? Also, what color is the house?
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Post 5 made on Sunday January 19, 2014 at 12:25
vwpower44
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Zing! Nice jab Fins!!
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OP | Post 6 made on Sunday January 19, 2014 at 13:21
Ernie Gilman
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On January 19, 2014 at 12:08, Fins said...
We cannot answer this question without all of the details. We need the zip code, the actual model of DTV receivers, and which dish is being used.

How do you expect any correct answer without every detail? Also, what color is the house?

You completely ASSume it's a house. Anything more I might say about that is irrelevant.

In keeping with many others who ask questions here, I've supplied enough information for you to waste YOUR time doing YOUR own research so YOU can give ME, for FREE, the results of YOUR VALUABLE consulting time.

Is that offensive? I think so, but people do it here all the time. Why do you only object when I do it?

About 350 people live at the location. There's one zip. You have google maps. I truly doubt that different dishes will have different azimuths. I'm sorry if I challenged you to figure that out for yourself, too... and on a weekend when there are football games!
A good answer is easier with a clear question giving the make and model of everything.
"The biggest problem in communication is the illusion that it has taken place." -- G. “Bernie” Shaw
Post 7 made on Monday January 20, 2014 at 01:57
3FG
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These satellites are in geostationary orbit which means that they are 22,200 miles up-- always directly above the earth's equator.  Two of the DirecTV satellites used in North America are at 103W, and another is a 99W.

Now consider houses at 30N latitude.  If the house is located at 103W, the dish needs to point south (with some elevation).  That's an azimuth of 180 degrees if the azimuth were measured with respect to true north, and closer to 168 or so if measured wrt magnetic north.  If the house is located further west, the azimuth needs to be less. For my area of California, the dish needs to point more in an eastern direction, and the required azimuth is 146 or more like 131 wrt magnetic north.

Cordova is shown as needing an azimuth of 103.8 (magnetic), or about 130 wrt true north. In other words, it needs to point within 5 degrees of south east.





 
OP | Post 8 made on Monday January 20, 2014 at 08:48
Ernie Gilman
Yes, That Ernie!
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3FG,
I believe there is still a satellite with SD programming at 101, and this client is not going to spend the money on HD. I believe that the LNB arm of all varieties of dishes point at the 101, so aiming at 101 is still the goal.

I completely get what you're talking about. In fact, the realization that DirecTV told me the azimuth for Cordova was 106 degrees is what confused me. That's 16 degrees E of S. A map showing the needed correction for magnetic North told me to correct this 19 degrees in a westerly direction (obviously I got that backwards), which brings us to 125 degrees.

Satsig.net says it's 131; dishpointer says it's 131; you say it's 146 but also say its' within 5 degrees of southeast. Southeast is 90 degrees (S) + 45 degrees = 135 degrees.

So all of this agrees except for the magnetic direction DirecTV gave me and the 146 that came up here somehow.

Thanks for the help!
A good answer is easier with a clear question giving the make and model of everything.
"The biggest problem in communication is the illusion that it has taken place." -- G. “Bernie” Shaw
Post 9 made on Monday January 20, 2014 at 11:46
3FG
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Ernie,
The 146 degrees I mentioned is for my house.  I described Cordova as 103.8 magnetic-- as obtained from the DirecTV app-- or about 130 wrt to true north.

I guess I need to be more blunt.  You have a basic misunderstanding.  South is 180 degrees of azimuth, not 90.   So SE is 135, but it is measured as 90 from north to east, and then an additional 45 to get to from east to southeast.  That's why I gave the example of the azimuth required for a dish at 103W.  You can use the DirecTV app with Lamar, CO, which is close to 103W.  The required azimuth is shown as about 167, which is close to 180 wrt true north.

 
OP | Post 10 made on Monday January 20, 2014 at 12:44
Ernie Gilman
Yes, That Ernie!
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On January 20, 2014 at 11:46, 3FG said...
Ernie,
The 146 degrees I mentioned is for my house.  I described Cordova as 103.8 magnetic-- as obtained from the DirecTV app-- or about 130 wrt to true north.

I see. Somehow I thought you meant it to be for Cordova.

I guess I need to be more blunt.  

I believe it is necessary to be blunt and not hint around when speaking of technical issues. Blunt is, after all, accurate.

You have a basic misunderstanding.  South is 180 degrees of azimuth, not 90.  

It sure is! In fact, D'oh!

There it is: the absolutely basic problem I've had with this; a stupid mistake. When I said 106 was 16 degrees east of due south, I should have realized that 106 is 74 degrees east of due south. Now, not that it's of much help, but that's also 16 degrees south of due east. Add in the magnetic correction that I had, 19 degrees... clockwise is the best way I can say that! -- and I've got 135 degrees.

The rest of your latest post is correct, but I was too stuck on my ridiculous mistake of S being 90 to learn anything from it. Thanks for the blunt, dude!
A good answer is easier with a clear question giving the make and model of everything.
"The biggest problem in communication is the illusion that it has taken place." -- G. “Bernie” Shaw


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