Computing Satellite Velocity using the Broadcast Ephemeris
(includes C code)
The technical paper which describes the bc_velo.c program is published in
GPS Solutions, Volume 8, Number 2, 2004 (in press). "Computing Satellite
Velocity using the Broadcast Ephemeris", by Benjamin W. Remondi
A set of equations has been derived which allows one to compute the velocity
vector for a GPS satellite using time derivatives of the Keplerian elements
and correction terms broadcast from the GPS satellites, as described in the
GPS Interface Control Document (ICD-GPS-200). This document is available
from the U.S. Coast Guard website at
http://www.navcen.uscg.gov/pubs/gps/icd200/default.htm.
A complete main program written in C (bc_velo.c) is included here to
illustrate how these equations can easily be incorporated into source code
to yield accurate velocity components. The reader can use this C code to
create a similar subroutine or function which will compute the position and
velocity of a satellite given the broadcast ephemeris data, the PRN name,
and a requested GPS time (transmission time) in units of GPS week and
seconds-of-week. In practice, a pointer to a broadcast structure would be
passed to a similar C function. It should be pointed out that the ambiguity
with respect to the GPS week has been ignored in this simple example
program.
Example main program (bc_velo.c)
Windows executable program (bc_velo.exe)
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