How to calculate distance (m) from reference position

[Aaron76]

Hello everyone,

this is my first post on this forum so apologies for being naive or making a fool of myself! My question relates to calculating the difference (in metres) from a reference point.

Essentially I need to ask if I've done this right....

I have a surveyed antenna position, and for a laugh I wanted to see how accurate my GPS receiver actually is. I logged a few hours of data and managed to get it into a *.csv format (so I have time, lat, long and altitude).

I wanted to plot the difference from truth (in metres) from the surveyed point in order to plot a lat/long difference scatter plot. I calculated the difference (in degrees) from the reference point and my logged data for lat/long, I then needed to get this in terms of metres and this is where I'm a bit lost.

From what I've read on the net the following is applicable:

(i) 1 degree Latitude = 111319.5 m
(ii) 1 degree Longitude = R*cos m

where R is 111319.5*COS(Ref latitude)

So, multiplying the latitude difference by (i) gave me the error (distance from truth) in metres, and multiplying the longitude by (ii) gives error in m from ref longitude.

Can anybody confirm that this approach is correct?

I'm keen to hear your opinions.

Best regards

Aaron

[lbendlin]

Why don't you simply use VisualGPS ? it does all this for you automatically.
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Lutz

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[Aaron76]

I want to be able to calculate it for myself, as I might be using the data for a report I'm putting together.

If VisualGPS permits data to be loaded in a reference point to be added then it could be useful. I'd still like to know how to calculate the error (m) manually, I'm sad that way!

Thanks for the info - I've never heard of this software.

[Kepler]

Here's a useful link which should give you the answer:
http://williams.best.vwh.net/avform.htm#flat

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