xsdop.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

%                              xsdop.m
%  Scope:   This MATLAB program computes sub-dilution of precision (sub-DOP) 
%           quantities, i.e. DOP quantities for all satellites subsets obtained
%           from eliminating one satellite from the original set.
%  Inputs:   - name of the output file containing the results if selected; the 
%              default in on screen
%            - name of the input file containing line-of-sight unit vectors;
%              each row contains a line-of-sight unit vector
%  Outputs:  - input/output data stored on the selected output file or
%              displayed on screen
%  Remarks: Five or more satellites are needed for the computation of sub-DOP.
%           The sub-HDOP is useful in the RAIM detection process [1], [2].
%  References: 
%           [1] Brown, A. K., Sturza, M. A., The effect of geometry on 
%               integrity monitoring performance. The Institute of Navigation
%               46th Annual Meeting, June 1990, pp. 121-129. 	
%           [2] Brown, R. G., A baseline RAIM scheme and a note on the
%               equivalence of three RAIM methods. Proceedings of the National
%               Technical Meeting, Institute of Navigation, San Diego, CA,
%               Jan. 27-29, 1992, pp. 127-137.
%  Usage:   xsdop
%  External Matlab macros used: sdop
%  Last update:  08/05/00
%  Copyright (C) 1997-00 by LL Consulting. All Rights Reserved.

clear  
yes = 'y';

%  Save the generated data into a specified file if desired

disp('  ');
answer1 = input('Do you want to save the generated data? (y/n)[n] ','s');
if  isempty(answer1)
   answer1 = 'n';
end
if strcmp(answer1,yes) == 1
   f2 = input('Specify the output file name (with extension) --> ','s');
else
   f2 = 1;        %  output to the screen
end

answer2 = yes;
while (strcmp(answer2,yes) == 1)
   clear   tt dops sgdop spdop shdop svdop stdop
   disp('  ');
   f1 = input('Specify the input filename (with extension) --> ','s');

%  Read the input data file

   tt = load(f1);
   [nrow,ncol] = size(tt);

   if  (ncol ~= 3) | (nrow < 5)
      disp('Error - XSDOP; check the input data file ');
      disp('  ');
      return
   end

%  Compute sub-DOP quantities

   [sgdop,spdop,shdop,svdop,stdop,dops] = sdop(tt);

%  Save input data and results into an external file

   fprintf(f2,'\n*********************************************************');
   fprintf(f2,'\n\n*****   Input data   ****** \n\n');

   for k = 1:nrow
      fprintf(f2,'LOS # %2.0f --> %12.7f %12.7f %12.7f\n',k,tt(k,1:3));
   end

   fprintf(f2,'\n*****   Results from the macro XSDOP.m   ***** \n\n');

   fprintf(f2,'Geometric Dilution of Precision (GDOP)  = %9.4f\n',dops(1));
   fprintf(f2,'Position Dilution of Precision (PDOP)   = %9.4f\n',dops(2));  
   fprintf(f2,'Horizontal Dilution of Precision (HDOP) = %9.4f\n',dops(3));  
   fprintf(f2,'Vertical Dilution of Precision (VDOP)   = %9.4f\n',dops(4));  
   fprintf(f2,'Time Dilution of Precision (TDOP)       = %9.4f\n\n',dops(5));  

   for k = 1:nrow
      fprintf(f2,'sub-GDOP %2.0f  = %9.4f\n',k,sgdop(k)); 
   end
   fprintf(f2,'max{sub-GDOP) = %9.4f\n',max(sgdop)); 
   fprintf(f2,'\n');

   for k = 1:nrow
      fprintf(f2,'sub-PDOP %2.0f  = %9.4f\n',k,spdop(k)); 
   end
   fprintf(f2,'max{sub-PDOP) = %9.4f\n',max(spdop)); 
   fprintf(f2,'\n');

   for k = 1:nrow
      fprintf(f2,'sub-HDOP %2.0f  = %9.4f\n',k,shdop(k)); 
   end
   fprintf(f2,'max{sub-HDOP) = %9.4f\n',max(shdop)); 
   fprintf(f2,'\n');

   for k = 1:nrow
      fprintf(f2,'sub-VDOP %2.0f  = %9.4f\n',k,svdop(k)); 
   end
   fprintf(f2,'max{sub-VDOP) = %9.4f\n',max(svdop)); 
   fprintf(f2,'\n');

   for k = 1:nrow
      fprintf(f2,'sub-TDOP %2.0f  = %9.4f\n',k,stdop(k)); 
   end
   fprintf(f2,'max{sub-TDOP) = %9.4f\n\n',max(stdop)); 

   fprintf(f2,'*********************************************************\n');

%  Select another computation, if desired

   disp('  ');
   answer2 = input('Do you want another computation? (y/n)[n] ','s');
   if  isempty(answer2)
      answer2 = 'n';
   end

end

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