Howdy,For rigorous treatment professors Ghilani and Leick have on-line courses at:

Howdy,FWIW, here is a photo of an NGS T4 in action. Observer is Ross Mackay, now the Geodetic Advisor Branch Chief.NGS T-4 in operation showing tripod...

Using Google Translate we get:HTH,DMM

Howdy,Does this help?I agree with the authors on the desirability of the adoption of a well-documented geoid information file format. Cheers,DMM

Howdy,I thought the new WGS84 realization was released in February? See:- Effective date February 08, 2012 For some interesting technical information...

Geoid12 interactive tool available nowHowdy,The interactive Geoid2012 tool at

Howdy,No doubt there are many approximate conversion factors, offset values from a variety of sources. The official US government Federal Register not...

Howdy,Yes, VERTCON is the official federal government conversion tool. Not knowing your accuracy requirements I cannot determine whether it is appropr...

ellipsoid heights to orthometric heightsHowdy,You need to be more specific. If h is ellipsoid height, H is orthometric height and N is the ellipsoid-g...

Howdy,I don't think this clarifies matters especially well but the NGS Glossary has these definitions:height - (1) The distance, in the direction of t...

Howdy,Mr Frame provides a good list of factors to consider in the determination of a GPS-derived height. When dealing with short baselines (<10 KM)...

Howdy,Are you sure they do not mean: determine the height of the control tower cab floor? This obviously must be done by conventional (not GPS) method...

Howdy,There are area requiring this purging. Many areas do not. While the monuments were purged in S La due to subsidence issues don't they remain acc...

Howdy,First of all, it is a little more complicated than merely comparing NAD83 to WGS84. At the time both systems were implemented they could be cons...

Level Run Confirms disk isn't the one onNGS DatasheetHowdy,I agree completely with Bill. Users who refuse to read and understand the contents of an N...

Howdy,You are correct about the 20 second collection interval. This was the default for Ashtech receivers. When GPS software merges data from differ...

Howdy,If you have a dual frequency receiver and antenna with a phase model, can set up a tripod and measure the height of the antenna reference point ...

Howdy again,In the event there is confusion on the matter, a RESET is not set to the original monument's height. A reset is set nearby the original m...