[TowerTalk] How accurate are iPhone Compass apps?

[dotravel at aol.com]

No hi-tech required, during a sunny day when your tower's shadow is the shortest it will be pointing North. If you want to get fancy just input your Lat. Lon.

Into this program and you will have your local solar noon -- your tower's shadow will be pointing North at that time.
http://www.srrb.noaa.gov/highlights/sunrise/sunrise.html     

If you paint a stripe on your roof where the shadow points or add a rock in the yard etc.  you'll have a nice reminder which way north is -- Google earth works just fine too --- tools/ruler/line! 

Regards, John NA6L 

 


-----Original Message-----
From: William Hein <bill.aa7xt at gmail.com>
To: towertalk <towertalk at contesting.com>
Sent: Fri, Dec 30, 2011 10:43 am
Subject: [TowerTalk] How accurate are iPhone Compass apps?


I have the Commander Compass (paid version 3.3.6) app on my iPhone 4S.  It's an 
mpressive looking app - says its "Mil Spec" - however I am wonder how accurate 
t is.  The manual says "The precision of the readings of the built-­‐in 
ardware sensors affects all of the Spyglass features. Spyglass averages the 
nput from the sensors over time and uses the basic motion dampening in order to 
chieve a better precision."  So I guess its down to the accuracy of the iPhone 
S GPS.
Sitting on my kitchen table it indicates an elevation of between 6893 and 6909 
eet.  If I average elevation readings over time will I improve the accuracy?  I 
sed the app's Location feature - it overlays an arial photo with crosshairs of 
he devices position and it looks to be VERY accurate, I'd say within a few feet 
it has a cross hair over my kitchen an I'm sitting at the kitchen table).  Is 
he elevation measurement equally accurate.
I also wonder how good this would be for finding true north and aligning Yagi 
ntennas and rotators.  Again, looks pretty accurate and seems to take 
eclination into account.
73
ill AA7XT

Date: Fri, 30 Dec 2011 10:22:10 -0600
rom: Richard Thorne <rmthorne at att.net>
ubject: Re: [TowerTalk] FAA & Towers, continued
o: towertalk at contesting.com
essage-ID: <4EFDE532.70506 at att.net>
ontent-Type: text/plain; charset=ISO-8859-1; format=flowed
My new iPhone 4S has a compass application with GPS coordinates.
Rich - N5ZC
On 12/30/2011 8:51 AM, William Hein wrote:
 Thanks for all for the great advice and info!  TowerTalk really proving its 
alue to me here.
 
 I am filing out FAA form 7460-1 online right now.  It asks for the exact 
ltitude ASL of my tower(s).  How do I find this out?  I can extrapolate from 
oogle Maps but that won't be accurate to a foot, neither will be my consumer 
rade GPS.
 
 73
 Bill
-----
illiam Hein, AA7XT
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