Welcome to the NavList Message Boards.


A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

Compose Your Message

Add Images & Files
    Re: Estimating height of eye
    From: Marcel Tschudin
    Date: 2013 Apr 11, 19:38 +0300

    Thank you, Richard Langley, for providing this information and giving
    an idea on the sort of attainable accuracy with consumer products.
    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:
    >> {at} 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)
    > View and reply to this message: http://fer3.com/arc/m2.aspx?i=123517

    Browse Files

    Drop Files


    What is NavList?

    Join NavList

    (please, no nicknames or handles)
    Do you want to receive all group messages by email?
    Yes No

    You can also join by posting. Your first on-topic post automatically makes you a member.

    Posting Code

    Enter the email address associated with your NavList messages. Your posting code will be emailed to you immediately.

    Email Settings

    Posting Code:

    Custom Index

    Start date: (yyyymm dd)
    End date: (yyyymm dd)

    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site