Tuesday, June 22, 2010

NGS Releases New Version of Software

The June 15 release of a newly updated version of NGS' PAGE-NT Global Positioning System (GPS) software will allow NGS state geodetic advisors, contractors, and state geodetic agencies to achieve better height accuracy (and horizontal accuracy) when positioning sites near the coast. In some areas, such as southern Alaska, the weight of the ocean's tides pressing down on the earth's crust can cause site motions of up to 6 centimeters in height and 5 mm horizontally. With relative positioning these effects are small when the distances between sites are small, because the sites tend to move up and down by the same amount. But when distances between sites are greater, and particularly when sessions are significantly different than 12 or 24 hours, these effects can cause height errors of several centimeters. The new software also includes a program which can be used to concatenate (append) two or three orbits files together when processing 24-hour sessions, thereby allowing users to be more efficient and to handle the latest GPS orbit format. For more information, contact Steve Hilla (301) 713-2851 x208.