
Measuring GPS Precision - zdw
http://blog.oplopanax.ca/2014/03/measuring-gps-precision/
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olympus
This is a nifty tool, but it doesn't offer statistically independent samples.
For many people, they don't care, but calculating from just a single track is
really a measurement of how much your track "drifts" as satellite move across
the sky, and not so much your location error.

A better (but still not perfect) way to do this is to take measurements at
several known location benchmarks, and then repeat this over a few days. Your
local city government probably has a listing of known benchmarks, in Las Vegas
the website is:
[http://www.lasvegasnevada.gov/Find/survey_benchmark.htm](http://www.lasvegasnevada.gov/Find/survey_benchmark.htm)

Doing this over the course of several days is important because you get data
from several different GPS satellites from several different positions in the
sky. This is much more labor intensive, but you will get a much better spec of
how much you can trust your GPS.

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danpat
I do this with some vehicle tracking equipment I run at ski resorts.

They run the machines over the snow on a daily basis. After a week or so of
passes over the same trail, you get a much better idea of where the average
line is.

The data my clients typically initially supply me with is usually taken with a
single pass using a Garmin unit strapped to the handlebars of an ATV. They
often wonder why it differs so much from the results they're getting from the
vehicle tracking equipment.

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TheLoneWolfling
...Until you get a GPS that assumes slow movement is measurement error and you
calculate infinite precision regardless of what actually is the case.

