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Thank you, Richard Langley, for providing this information and giving
an idea on the sort of attainable accuracy with consumer products.

Marcel

On Thu, Apr 11, 2013 at 3:48 PM, Richard B. Langley  wrote:
> ________________________________
>
> Sorry for being late in providing more information but the life of a prof is
> a busy one, well, at least for me. You want to determine a height difference
> of a few metres at the same location with an accuracy of hopefully 10%. If
> the height difference is 3 metres, say. then you are looking for 30 cm, one
> sigma. Then you will need to make carrier-phase measurements using a
> survey-grade GNSS (GNSS = global navigation satellite systems, including
> GPS, GLONASS, etc.) receiver and process them using either the precise point
> positioning technique or double-differencing with respect to a reference
> station. I think pseudorange measurements are just too noisy to give you the
> desired accuracy even in differential mode.
>
> Attached are a few slides from my external Differential GNSS Course (to be
> given next in Nashville in September at the ION meeting). The first shows
> the different kinds of positioning available with GNSS, then horizontal and
> vertical positioning accuracies with standalone pseudorange measurements
> (like those used by handheld receivers) but as determined at some FAA
> monitoring stations, then WAAS-corrected position accuracies using the same
> stations.
>
> To get back to celnav, I will have to determine the height of my eye when I
> go to the Big Island of Hawaii a couple of weeks from now at a house up from
> Kona with a nice view of the Pacific. I'll do some GPS height averaging but
> as I'm just taking my plastic Davis sextant, I'm not looking for high
> accuracy, just a bit of fun, to break up the monotony of sitting around the
> pool. ;-)
>
> -- Richard Langley
>
>
>
>
> On 2013-04-10, at 3:45 PM, Marcel Tschudin wrote:
>
>>
>> @ Richard Langley
>>
>> I noticed from your contributions and publications that you seem to be
>> more deeply involved in the subject of GPS. May I therefore ask you:
>> Do you have an idea on the sort of accuracy one may "generally" expect
>> when measuring with GPS at the same location (few tenths of meter
>> distance) height *differences* between about 2 and 5 m ? Would it be
>> possible to measure at the two locations the height and obtain their
>> difference to about +/- 20% or even better to e.g. +/- 10% and what
>> type of equipment would this require?
>>
>> Thanks in advance for some hints.
>
> [[rest snipped]]
>
> -----------------------------------------------------------------------------
> | Richard B. Langley                            E-mail: lang---ca         |
> | Geodetic Research Laboratory                  Web: http://www.unb.ca/GGE/
> |
> | Dept. of Geodesy and Geomatics Engineering    Phone:    +1 506 453-5142
> |
> | University of New Brunswick                   Fax:      +1 506 453-4943
> |
> | Fredericton, N.B., Canada  E3B 5A3
> |
> |        Fredericton?  Where's that?  See: http://www.fredericton.ca/
> |
> -----------------------------------------------------------------------------
>
>
> Attached File: 123517.slides_from_ion_dgnss_course.pdf (no preview
> available)
>
> : http://fer3.com/arc/m2.aspx?i=123517

   

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