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Azimuth And Gps?


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An azimuth angle is the number of degrees from north (either true north or magnetic north). The easiest way to do this with a GPSr might be to mark a waypoint at your location and then project a waypoint at 152° from that waypoint for, say, 20 or 30 feet. Then navigate to the projected waypoint and set a stake (or just stick a sharp stick into the ground). The stick is then at 152° from the original spot. It would lie at roughly 5 o'clock on a clock dial oriented north. (5 o'clock is 150°)

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It really doesn't matter if you go clockwise or counter-clockwise. 152 degrees is 152 degrees from North. Whether you spin left or spin right to get there, you'll still end up at 152 degrees. You'll just spin a little more if you go counter-clockwise.

 

A more important question would be is that 152 degrees from Magnetic North, or 152 degrees from True North? Depending on where you are, there could be a difference of 20 degrees or more!

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But of course if you spin counter clockwise, you'll need to rotate 208° to land at 152°, so that is taking the long way.

 

Good point magnetic vs. true. If they say to use a compass, they are using magnetic bearings. If they don't say, then, well, I don't know.

 

How much it matters depends upon where you are. You can check here.

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An azimuth angle is the number of degrees from north (either true north or magnetic north). The easiest way to do this with a GPSr might be to mark a waypoint at your location and then project a waypoint at 152° from that waypoint for, say, 20 or 30 feet. Then navigate to the projected waypoint and set a stake (or just stick a sharp stick into the ground). The stick is then at 152° from the original spot. It would lie at roughly 5 o'clock on a clock dial oriented north. (5 o'clock is 150°)

Sputnik gives a good way. I'd project the waypoint though much furthur - let's say a mile. Then walk towards the projected waypoint and set a stake after 20-30 feet. If you project the waypoint itself for 20 feet, the inherent error of the GPS will throw you off.

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A 30 foot hike no matter how far your projection is, will be very inaccurate for aiming an antenna. Also, this will not actually put you at an accurately known position until you reach the projection.

 

With a 20 foot error in the GPS, you need a target some 500 feet away to get an accurate bearing. It might be better if you did a reverse bearing. Set the antenna as your destination waypoint and walk out a distance until your bearing back to the antenna is 180 + 152 or 332. Then aim the antenna toward this point.

 

Oh, and unless they say differently, I would expect the azimuth angle to be true, not magnetic. But then the angle depends on where you are located, so you should check with the source of the info. Around here the difference is 11 degrees, but other places it can be as much as 30 or more.

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You said this was for aiming a Dish. I have one of those. For me I used the angle to get close, but then it was trial and error and bumping it a little left or right in order to get the signal. It takes two people, one on the house and one watching the TV screen to check the signal bars. The original method described by Sputnik 57 will get you close. Or you could just set the electronic compass to display degrees, and turn it until it reads 152.

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Why not simply use a good magnetic compass, then do essentially what tossedsalad said: Go out 500' or so and do a back bearing to the antenna? Or---if there is a landmark of some sort conveniently located at 152° from the antenna---just aim the antenna at that. It seems like a gps is overkill here and unless you live near a large magnetite deposit a compass will probably be more accurate (although, admittedly, maybe not as much fun).

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I am always confused with this when asked.

 

I alway thingk when they say 152 degrees they mean a angle that the dish needs to point at in the air from a flat surface. As in 90 degrees would point straight up and 152 would be the spot of the satellite orbit.

 

So I would get my 180 degree protractor out and then set the angle of 152 degress for the angle of the cone to sit.

 

I know friends who can't use a dish because of tall buildings or tree that block the signal.

 

So to set up a dish you really need to have e a compass degree to face and azimuth to aim at.

 

:unsure:

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I don't own a dish, but I would think you would need two angles, one for altitude and one for azimuth, just as you do for aiming telescope that doesnt have an equitorial mount. The altitude angle is the angle skyward (with 0° at the horizon and 90° at zenith). The azimuth angle is the direction around the imaginary plane of the earth (0° North, 90° East, 180° South, etc.). The OP was asking about the azimuth angle.

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