xsvpeph.m

GPS TOOLBOX包含以下内容： 1、GPS相关常量和转换因子； 2、角度变换； 3、坐标系转换： &#61656 点变换； &#61656 矩阵变换； &#61656 向量变换

%                                xsvpeph.m
%  Scope:   This MATLAB program computes ECEF satellite position based on 
%           satellite ephemeris data; WGS-84 constants are used.
%  Usage:   xsveph
%  Inputs:  - tsim, GPS system time at time of transmission, i.e. GPS time
%             corrected for transit time (range/speed of light), in seconds
%           - satellite ephemeris data from a specified data file; default 
%             data are given. The ephemeris satellite data are specified in
%             the following order (each record is for a different satellite):
%             - satellite number
%             - toe, reference time ephemeris, in seconds         
%             - smaxis, satellite semi-major axis (a), in meters
%             - ecc, satellite eccentricity (e) 
%             - izero, inclination angle at reference time (I_0), in radians 
%             - razero, right ascension at reference time (OMEGA_0), in radians 
%               (longitude of ascending node of orbit plane at weekly epoch)
%             - argper, argument of perigee (omega), in radians
%             - mzero, mean anomaly at reference time (M_0), in radians      
%             - radot, rate of right ascension (OMEGA_DOT), in radians/second 
%             - deln, mean motion difference from computed value (delta_n), in 
%               radians/second 
%             - idot, rate of inclination angle (I_DOT), in radians/second 
%             - cic, amplitude of the cosine harmonic correction term to the
%               angle of inclination, in radians
%             - cis, amplitude of the sine harmonic correction term to the
%               angle of inclination, in radians
%             - crc, amplitude of the cosine harmonic correction term to the
%               orbit radius, in meters
%             - crs, amplitude of the sine harmonic correction term to the
%               orbit radius, in meters
%             - cuc, amplitude of the cosine harmonic correction term to the
%               argument of latitude, in radians
%             - cus, amplitude of the sine harmonic correction term to the
%               argument of latitude, in radians
%           - name of the input data file (optional)
%           - name of the output file (optional)
%  Outputs: - input/output data stored on the selected output file or
%             displayed on screen
%  External Matlab macros used:  svpeph, wgs84con
%  Last update:  11/11/00
%  Copyright (C) 1996-00 by LL Consulting. All Rights Reserved.

clear 
yes = 'y';

%  Specify the ephemeris data for the satellite

disp('  ');
answer1 = input('Do you want to use the default data? (y/n)[y] ','s');
if isempty(answer1)
   answer1 = yes;
end   
disp('  ');
svid = [];
if (strcmp(answer1,yes) == 1)
   tsim   =  238205.;            %  GPS system time at time of transmission,
                                 %  i.e. GPS time corrected for transit time 
                                 %  (range/speed of light), in seconds
   eph(1) = 1;                   %  default value
   eph(2) =  244800.;            %  reference time ephemeris (toe), in seconds     
   eph(3) =  26560360.0409;      %  semi-major axis (a), in  meters
   eph(4) =  0.00528036116157;   %  satellite eccentricity (e)
   eph(5) =  0.970306409202;     %  inclination angle at reference time (I_0), 
                                 %  in radians
   eph(6) =  -3.09805209344;     %  right ascension at reference time (OMEGA_0), 
                                 %  in radians (longitude of ascending node
                                 %  of orbit plane at weekly epoch)
   eph(7) =  2.88898057517;      %  argument of perigee (omega), in radians
   eph(8) =  -0.784710884484;    %  mean anomaly at reference time (M_0),in rads.
   eph(9) =  -7.84889836669e-9;  %  rate of right ascension (OMEGA-DOT), in rad/s
   eph(10) = 4.22624746874e-9;   %  mean motion difference from computed 
                                 %  value (delta_n), in radians/second
   eph(11) =  -5.7145237e-12;    %  rate of inclination angle (I_DOT),in rad/sec.
   eph(12) =   3.72529029846e-8; %  cic, in radians
   eph(13) =  -2.421438694e-8;   %  cis, in radians
   eph(14) =  176.59375;         %  crc, in meters  
   eph(15) =  -72.09375;         %  crs, in meters  
   eph(16) =  -3.73087823391e-6; %  cuc, in radians
   eph(17) =  1.07381492853e-5;  %  cus, in radians
   nrow = 1;  
else
   tsim = input('Specify the time of simulation, tsim, e.g. 238205., --> ');
   disp('  ');
   fname = input('Specify the ephemeris data filename (with extension) --> ','s');
   eph = load(fname);
   [nrow,ncol] = size(eph);
   if  nrow ~= 17
      disp('XSVPEPH - Error: check the input data ');
      disp('  ');
      break;
   end   
end

%  Select the output file

answer2 = input('Do you want to save the generated data? (y/n)[y] ','s');
if  isempty(answer2)
   answer2 = yes;
end
disp('  ');
if strcmp(answer2,yes) == 1
   f2 = input('Specify the output filename  -->  ','s');
else
   f2 = 1;     %   output to the screen
end

disp('  ');
fprintf(f2,'******************************************************************\n');
fprintf(f2,'\n*****Simulation time  = %16.7e seconds\n',tsim);
for k = 1:nrow
   svid(k) = eph(k,1);
   temp = eph(k,2:17);
   
%  Compute the ECEF satellite position 

   pse = svpeph(tsim,temp);

%  Save the generated data into a specified file or displayed on screen

   fprintf(f2,'\n*****Satellite ephemeris data for satellite  %3.0f\n',svid(k));
   fprintf(f2,'toe    = %22.14e seconds\n',eph(1));
   fprintf(f2,'smaxis = %22.14e meters\n',eph(2));
   fprintf(f2,'ecc    = %22.14e \n',eph(3));
   fprintf(f2,'izero  = %22.14e radians\n',eph(4));
   fprintf(f2,'razero = %22.14e radians\n',eph(5));
   fprintf(f2,'argper = %22.14e radians\n',eph(6));
   fprintf(f2,'mzero  = %22.14e radians\n',eph(7));
   fprintf(f2,'radot  = %22.14e radians/second\n',eph(8));
   fprintf(f2,'deln   = %22.14e radians/second\n',eph(9));
   fprintf(f2,'idot   = %22.14e radians/second\n',eph(10));
   fprintf(f2,'cic    = %22.14e radians\n',eph(11));
   fprintf(f2,'cis    = %22.14e radians\n',eph(12));
   fprintf(f2,'crc    = %22.14e meters\n',eph(13));
   fprintf(f2,'crs    = %22.14e meters\n',eph(14));
   fprintf(f2,'cuc    = %22.14e radians\n',eph(15));
   fprintf(f2,'cus    = %22.14e radians\n\n',eph(16));
   fprintf(f2,'ECEF position for the selected satellite %3.0f based on ',svid(k));
   fprintf(f2,'ephemeris data\n');
   fprintf(f2,'x-component  = %22.14e meters\n',pse(1));
   fprintf(f2,'y-component  = %22.14e meters\n',pse(2));
   fprintf(f2,'z-component  = %22.14e meters\n\n',pse(3));
end
fprintf(f2,'******************************************************************\n\n');

disp('End of the program  XSVPEPH ');
disp('  ');