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Thank you, Brad, for finding this Android app for me. I presume that
the 1 m represent an absolute accuracy and that measurements of height
differences may possibly attain a higher accuracy. I will give this
affordable gadget a try and perform some tests with it.

Marcel


On Wed, Apr 10, 2013 at 6:28 PM, Brad Morris  wrote:
> ________________________________
>
> Hi Marcel
>
> 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.
>
> Brad
>
> On Apr 9, 2013 6:21 AM, "Marcel Tschudin"  wrote:
>>
>> ________________________________
>>
>> 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
>>
>> : http://fer3.com/arc/m2.aspx?i=123477
>
> : http://fer3.com/arc/m2.aspx?i=123498

   

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