We are using ArcPad 10 and Trimble GeoXH to position electric transmission structures. We use the ArcPad "Find" tool to enter coordinates for the required position. We will use the Oregon Real-Time GPS Network to get corrections in the field.
In order to confirm GPS accuracy we want to use the "Find" tool to enter the coordinates of a known monument and compare the coordinates returned by the unit.
I have read that NAD83(91) (which I assume is an Oregon HARN epoch) would be equivalent to WGS84 (i.e. no transformation is required) and also read that there is an approximately 1 meter difference in coordinates expressed in WGS84 and NAD83 HARN datums.
Given that the ArcPad "GPS Preferences" are set to Datum = D_WGS_1984 (6326), Spheroid = WSG_1984 (7030) and the coordinates of the known point are Latitude and Longitude in NAD83(91); what, if any, transformation should be used?
Thanks,
Neal Myers
GIS Supervisor
Central Lincoln PUD
