A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Brad Morris
Date: 2013 Apr 10, 11:25 -0400
There is an app in the Android market called "Precision GPS Pro". The cost is US$0.99
It claims a 1 meter elevation accuracy after averaging, although they do not indicate how long an average you require to achieve that.
The free version of this app does not do elevation averaging.
I have not tried this app.
In my sunset observations the guesstimates for the HoE of probably not better than +/- 20% are indeed a weak point. But how weak? The dip is proportional to the square root of the HoE which means that the estimated dip error is only half of the estimated HoE error. For the average HoE of 3.5m the "normal" dip is 3.3 moa and a 10% error of it therefore +/- 0.33 moa. This corresponds in the photo to slightly more than one pixel which is 18 seconds of arc. Frank, you mentioned estimating HoE within about +/-5%. I'm wondering whether you would also be able to attain such an accuracy by climbing over the rocks as shown in my photo: https://mail-attachment.googleusercontent.com/attachment/u/0/?ui=2&ik=b33d2c81ba&view=att&th=13ddab531282f2e7&attid=0.1&disp=inline&realattid=f_hf5h7cfp0&safe=1&zw&saduie=AG9B_P-DvbGAuAxTxtruQd29-avq&sadet=1365502394438&sads=w4N-7jPt0vbdfN6eZHKSEaR8vQ0 For my average of 3.5 m this would correspond to less than 20 cm or what might be more familiar to you to about half a foot. In order to verify my guesstimates I do indeed consider to perform some additional measurements. I'm wondering how good I could measure it using GPS and also the Russian version of it. I have no experience in using these systems. I understand that I would have to measure both levels, eye and sea level and then take the difference. Is there an Android application which I could load on my Samsung pad allowing to collect measurements over a longer time period which then calculates a mean altitude and its standard deviation? What are the sort of result one could obtain this way? Marcel
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