Gps datum conversion

[goodgps]

There is a secret station X which has lat / long / and MSL elevation (assumed NAVD88) info was provided . The station x was observed in 2001. using geoids etal applicable at that time.

the mission;
Observe some chosen points, establish the MSL at the chosen points and provide an accurate azimuth ties to secret station X.

Station X cannot be accessed.

The Chosen points were observed long static and processed thru OPUS.

OPUS provides Navd88 vertical datum (geoid03) and current NAD83.

It has been experienced that recent observations of "known" stations, yeilds different results both horizontal and vertical. to the tune of about 0.27 feet.

Is there a program or conversion formulae which can convert the secret station X datum to todays datum or Chosen back to Secret ?

G

[Stan_K]

You might have enought info to use NGS HTDP (Horizontal Time-Dependent Positioning) Program.
url\http://geodesy.noaa.gov/TOOLS/program_d ... l#HTDP\url

Stan

[goodgps]

Thanks Stan,

I will try that right away.

Using "classical methods" ie turning multiple angles to the center point of Station X, we missed the previous Geo coordinates by 0.68 feet.

maybe this correction will tighten that up a bit.