[time-nuts] Computing GPS Distance Error in Time

Chris Albertson albertson.chris at gmail.com
Sat Nov 9 12:08:15 EST 2013


If you are dealing with positions that are only up to 5,000 feet distance,
you can assume the Earth is flat and simply plot locations using maybe
"gnuplot"  For such a small area the conversion of latitude and longitude
to (x,y) is linear.

Over larger areas you may want to integrate your data with maps and need
access to function to compute bearing angles and distances  on a spheroid
which is non-trivial.  GIS software like GQIS allows you to plot data on
the Earth's surface.


On Thu, Nov 7, 2013 at 10:41 AM, Bob Stewart <bob at evoria.net> wrote:

> Hi Mark,
>
> What I was hoping for was some canned software that will plot position on
> the display until told to clear it so I can get a visual.  I've tried
> foxtrotgps, but it clears its screen at any and every opportunity, so
> barring getting into the code that's not going to work.  But I can capture
> the position data from my Adafruit and add it to the plot I'm already doing
> for timing.  So that will work.
>
> thanks,
>
> bob
>
>
>
>
>
> >________________________________
> > From: Mark Sims <holrum at hotmail.com>
> >To: "time-nuts at febo.com" <time-nuts at febo.com>
> >Sent: Thursday, November 7, 2013 12:14 PM
> >Subject: [time-nuts] Computing GPS Distance Error in Time
> >
> >
> >I'm not using any special surveying software,  just some code that I
> wrote.  The controller box and remote box both have GPS units in them.  The
> controller periodically requests the remote unit's position and just
> calculates the vector distance/bearing between the two units.  The
> application was intended to work with the boxes spaced 50-5000 feet apart.
>  I was rather surprised how well they worked very close together.  The next
> step is to add a magnetic compass module to the controller box so that it
> can draw a map of the remote units in relation to the orientation of the
> controller box.
> >--------------
> >What type of real-time surveying software are you using?  I'm looking for
> surveying/plotting software for Linux to keep a close on the timing
> stability of my Adafruit.
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> >
> >
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-- 

Chris Albertson
Redondo Beach, California


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