mecefeci.m

GPS software toolbox for GPS receiver development

%                                mecefeci.m
%  Scope:   This MATLAB macro constructs the transformation matrix from ECEF 
%           frame to ECI (Earth Centered Inertial) frame; WGS-84 earth's 
%           rotation rate constant is used.
%  Usage:   moutput = mecefeci(dtime)
%  Description of parameters:
%           dtime    -  input, time elapsed since reference time, in seconds
%           moutput  -  output, two-dimensional real array containing the 
%                       transformation matrix from ECEF frame to ECI frame
%  Remarks: The ECEF to ECI transformation takes into account only Earth's 
%           rotation, i.e. no Earth's precession and mutation effects.
%  External Matlab macros used:  wgs84con
%  Last update:  04/05/00
%  Copyright (C) 1997-00 by LL Consulting. All Rights Reserved.

function   moutput = mecefeci(dtime)

wgs84con;
%  global constants used: rot_rate (WGS-84 earth rotation rate, in rad/sec)

swie = sin(rot_rate*dtime);
cwie = cos(rot_rate*dtime);

moutput = eye(3);  
moutput(1,1) =   cwie; 
moutput(1,2) = - swie;
moutput(2,1) =   swie;
moutput(2,2) =   cwie;