Does Global Mapper Mobile Pro convert from WAAS (ITRF) to NAD83 on the fly?

bisenberger
bisenberger Global Mapper UserTrusted User
in GPS Features
I have a survey grade GPS that can use WAAS correction, but WAAS is based on an ITRF frame, so that a WAAS position varies from the NAD83 position by about a 1 meter. My map data is typically referenced to NAD83. Can Global Mapper Mobile Pro project the incoming GPS data that is corrected with WAAS to NAD83 on the fly to eliminate the 1 meter position difference?

Answers

  • bisenberger
    bisenberger Global Mapper User Trusted User

    On January 20, 2002, the latest realization of WGS 84, called WGS 84 (G1150) was adopted and is the current version. This realization is based on the ITRF 2000.

    Between the first implementation of WGS 84 (Original) and the current revision, the differences can be 1-2 meters. For North America, the following online datum transformation tool from the NGS can be used:
    http://www.ngs.noaa.gov/cgi-bin/HTDP/htdp.prl?f1=4&f2=1


    The above information was copied from this website:

    https://sxbluegps.com/a-word-about-datum/

  • bisenberger
    bisenberger Global Mapper User Trusted User

    The World Geodetic System 1984 - WGS 84 (TRANSIT), WGS 84 (G730), WGS 84 (G873) and WGS 84 (G1150)

    The Department of Defense (DoD) developed the WGS 84 reference system to support global activities involving mapping, charting, positioning and navigation. DoD established the original WGS 84 reference frame in 1987 using Doppler observations from the Navy Navigation Satellite System (NNSS) or TRANSIT and named it as WGS 84(TRANSIT). This original WGS 84 realization essentially agrees with NAD 83(1986). It is generally assumed that WGS 84 (TRANSIT) is identical to NAD 83 (1986) within the conterminous US.

    In 1994, DoD introduced a realization of WGS 84 that is based completely on GPS observations, instead of Doppler observations. This new realization is officially known as WGS 84 (G730) where the letter G stands for "GPS" and "730" denotes the GPS week number (starting at 0h UTC, 2 January 1994) when the National Imagery and Mapping Agency (NIMA) started expressing their derived GPS orbits in this frame. This realization is generally assumed to be identical to ITRF92( epoch 1994.0) at the few centimeter level.

    A third realization of WGS 84, called WGS 84(G873), was introduced in 29 September 1996 and adopted by the GPS Operational Control Segment in 29 January 1997. This realization is also based completely on GPS observations. Again, the letter G stands for "GPS" and "873" refers to the GPS week number starting at 0h UTC, 29 September 1996. This realization is generally assumed to be identical to ITRF 94 (epoch 1997.0) at few centimeter level.

    The latest realization of WGS 84, adopted in 20 January 2002, is termed WGS 84 (G1150). It is generally assumed to be identical to ITRF 2000 (epoch 1997.0) at one centimeter level. This latest realization differs from NAD 83 (1986) by about 2 meters.

    Source website:

    https://vdatum.noaa.gov/docs/datums.html#:~:text=The latest realization of WGS,1986) by about 2 meters.

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