GPS Question

SWMODave

Sergeant Major
Thread Medic
Joined
Jul 23, 2017
Location
Southwest Missouri
I apologize if this is the wrong place to ask this but I figure relic hunters might be good people to ask.

If someone were to give you a GPS coordinate, and then tell you to go so many feet east and so many feet south from that coordinate, with just those instructions would one be able to figure out the new GPS coordinate without actually walking it first?

And if so, can you point me to the best layman's website that can teach me how to figure it out for myself.

TIA
 
One way or another, I expect you will have to plot the original postion and then recalculate from that. You might try using Google Earth, that has plotting and measuring tools that will allow you plot and read the new location fairly precisely.

Here's a made-up example with the original coordinates (top), and a measure position 500 feet south and 200 feet west of it:

Sample.jpg
 
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I apologize if this is the wrong place to ask this but I figure relic hunters might be good people to ask.

If someone were to give you a GPS coordinate, and then tell you to go so many feet east and so many feet south from that coordinate, with just those instructions would one be able to figure out the new GPS coordinate without actually walking it first?

And if so, can you point me to the best layman's website that can teach me how to figure it out for myself.

TIA

You could but it's a bit mathematically complicated. That's because the earth is not flat (not going to argue that here) and so the degrees, minutes, seconds change with regard to curvature. Think of it as having a Z element in addition to just X and Y. That's why a degree gets smaller on the ground the closer to the poles you go.

The UTM coordinates you see on a USGS topo quad (in addition to the Lat and Long) are a way to eliminate the Z element so one can just measure on a square grid (only really works on small areas due to increasing error). So, short answer: take your device with you or use UTM.
 
@AndyHall, is correct but you have to remember that GPS is not in feet. Here is a link to a app for your cell that I use when I relic hunt that helps me track what I find, where I found it and tracks everywhere I walk. At first I was like yea right, but it works

I'm a metal detectorist from England, and a long term member of detectorist .co.uk. I have recently made a metal detectorists Android tracking app. I've called Tect O Trak. I thought you might like to try it. This is the app I couldn't find.. So I made it myself. This application allows the user to track their movements within a pre defined area. You can save and resume searches, add / revisit findspots, and make detailed records. Get it here https://play.google.com/store/apps/d....tectotraklite
 
Google Earth allows you to mark off distances in almost any unit -- feet, meters, yards, smoots, etc.
 
@AndyHall Really how do I convert it feet?
 
Google Earth will display coordinates in degree, minutes, seconds; degrees, decimal minutes, or UTM. You first navigate to the reference point provides, and place a Google Earth landmark there. Then using the measuring tool, mark off lines of whatever distance and direction required (in the example above, 500 feet south and 200 feet west). Then that will give you the desired position. Put another mark there and it will so you the desired coordinates of the new location.

Here is the same example as above using UTM coordinates:

Sample 2.jpg
 
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Most areas have three easts and souths. Magnetic east, true east, and grid east. If you are talking feet and not yards or miles the difference is not too much.
 
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