Spectra Precision Survey Pro CE v3.60 GPS User Manual - Manual (Page 19)

GPS Coordinates
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Geoid Models in TDS Software
Survey Pro has several geoid models in the coordinate system
database. All of the geoid models use data files in geoid grid file
(*.GGF) format.
Note: To use a geoid model, geoid data files (*.GGF) must be in the
Geodata directory.
• Users in the U.S.A., Mexico, and the Caribbean can use either the
NGS Geoid96 or the NGS Geoid99 models. This coverage
includes the continental United States, Alaska, Hawaii, Mexico,
and the Caribbean.
• Users in Canada can use the Geodetic Survey Division CGG2000
model. See the GSD web site for available data sets.
• Users anywhere in the world can use the NIMA worldwide 15-
minute geoid height grid data file, WW15mGH.ggf. This file
covers the entire globe on a 15’ x 15’ grid.
• Users in Australia can use the AUSGEOID98 data set. This data
set is available in several overlapping sub grid files in the *.GGF
format at the TDS web site.
Note: To use any of these geoids with Survey Pro, you need to
convert the files from their native format into the *.GGF format. This
is done with the Geoid Sub Grid function in survey Link. The
required NGS and the NIMA geoid model data files are supplied free
of charge on the TDS Survey Works CD. The Canadian GSD geoid
models are a licensed data set, so you have to contact Natural
Resources Canada to obtain the data in the NGS.bin format to use
with the Survey Link Geoid Sub Grid extraction utility. The
Australian geoid model is available in *.GGF format for download at
the TDS web site on the GPS page.
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6 Go to www.tdsway.com and select Downloads.