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<p><font size="+1">In order to make widely available some wise
advice, I'm sending to this list a message I received from Neil
B. In addition to Neil's message below, I want to mention that
Nicolas Cadieux also provided similar information, saying I'd
have to pay around $1,000 for equipment that gives consistently
accurate location coordinates. And thanks, also to Falk
Huettmann and Bernd Vogelgesang for their replies. </font><br>
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<div class="moz-forward-container">Message from Neil B:<br>
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<div class="moz-forward-container">Hello Stephen.
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<div dir="ltr">Glad that you're having success. I would like to
start off by saying that it is best to always reply to the
mailing list and not directly to the person who submitted the
email. Mailing lists work really well in that there is a pool
of people out there who may be able to offer advice or may
have an alternate method to solve the problem that may turn
out to be a better way. On the flip side by maintaining the
email chain through the mailing list, the follow up emails
that provide information are stored in the archives which
benefits anyone searching the internet to have the complete
trail of information.</div>
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<div>As far as your results they are acceptable for the device
you're using. GPS in phones are never built to precision
survey standards and there is no reason for them to be. If
you're within 30ft of where the phone thinks you should be
then you can easily navigate the rest of the way by visual
sight. High end equipment to achieve sub-inch accuracy is
probably in the range of thousands of dollars. One thing to
keep in mind is there is a difference between the accuracy of
a device and to what level of precision they display. While
the app on the phone may display 8 decimal places of a
lat/long coordinate and tell you if you have moved a foot, it
doesn't help that the coordinate it is displaying is out +/-
30 feet. The accuracy of a device can also be affected by the
environment where the device is being operated. In regards to
cell phones, they use multiple sources to determine location
such as GPS, cell phone towers, and wifi points to perform the
triangulation. Lack of line of sight to satellites, signals
from cell towers bouncing off of surrounding buildings, or
someone's wireless router using inaccurate position
information can all affect the accuracy of what is being
displayed on your phone.</div>
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<div>So the question is how are you determining that the
coordinates are wrong? If you have information that you trust
to be authoritative then adjust your points to those values
and carry on. I have no advice or opinions on inexpensive
devices that may help with a more accurate reading.</div>
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<div>Please do not respond directly to me. This email account is
not actively monitored and I don't always have the time to
follow up with the emails. All the best with your endeavours.</div>
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<div>~Neil B.</div>
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<div dir="ltr" class="gmail_attr">On Fri, May 15, 2020 at 7:52
PM Stephen Sacks <<a href="mailto:sacks44@earthlink.net"
moz-do-not-send="true">sacks44@earthlink.net</a>>
wrote:<br>
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<p><font size="+1">Hi Neil, <br>
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<p> With your help, I have successfully brought the
corners of our gardens back from Pennsylvania to the
Promenade here in Brooklyn Heights, New York. Thank
you.<br>
At the risk of wearing out my welcome, I'm now asking
for more advice. My point features are approximately
where they should be but not exactly, some points are
just a few feet off and some are 10 or even 30 feet
off. I imported the data trying both EPSG 4326 and
4269.<br>
I'm now convinced that the problem is due to (1) my
Google Pixel 3 cellphone, (2) the app I'm using
("Latitude Longitude" published by gps-coordinates),
and especially (3) my less-than-steady hands. I
capture coordinates by standing at spot, waiting for the
blue dot to settle, and then touching the blue dot.
Often I don't touch the screen at exactly the right
place. I tried another app ("GPS Coordinates" published
by Financept) which is better in that it allows me to
zoom in, but I'm still not always getting it right.<br>
I'm thinking now that I need specialized equipment.
That is what I want to ask you. Can you recommend some
inexpensive device that will allow me to simply press a
button to record accurately the coordinates of the point
where I'm standing? Keep in mind that this is a
community project with no funding. I live on Social
Security and a university pension, but I'm willing to
pay something in the range of $50 or a bit more. Do you
know of anything at such a modest price, or would I have
to pay much more? Or perhaps you know of better
software for my Android Pixel 3 phone.<br>
Thanks in advance for any advice you might offer.<br>
Steve<br>
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