Jan Kouba
Geodetic Survey of Canada
Natural Resources Canada (NRCan)
616 Booth Street
ottawa, Ontario, Canada KIA 0E9
Fortran 77 source code for transforming GPS orbit files in SP3 format between different realizations of ITRF's used by the International GPS Service (IGS) since 1994. The code can also be used for transforming a set of station coordinates at the same epoch to and from different ITRF's. Optionally, an ERP file in the IGS ERP format can be transformed to and from different ITRF's. The related technical paper was published in GPS Solutions, Volume 5, Number 3, Winter 2002.
The link below has the latest source code from the Geodetic Survey of Canada (and files to transform between NAD83 and ITRF2008/IGS08)
Link to the Geodetic Survey of Canada website (source code file trnfsp3n.f is in trnfsp3.tar).
This link is to an older *.zip file with the original source code (and numerous files to transform between various older ITRF frames)
The *.zip file with the original code (trnfsp3n_dos.zip)
2021