xebudget.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

%                               xebudget.m
%  Scope:   This MATLAB program determines the error budget for a specified 
%           input data set.
%  Usage:   xebudget
%  Inputs:  - input data from keyboard as follows
%             (1)  space segment error
%             (2)  control segment error
%             (3)  user segment, tropo error
%             (4)  user segment, iono error
%             (5)  user segment, multipath error
%             (6)  user segment, receiver error
%             (7)  PDOP value
%             (8)  HDOP value
%             (9)  VDOP value
%             (10) TDOP value
%             A complete default data set is provided. 
%  Outputs: - selected input data 
%           - computed quantities, namely
%             (1)  URE (User Range Error), in meters
%             (2)  UEE (User Equipment Error), in meters
%             (3)  URE (User Equivalent Range Error), in meters
%             (4)  SEP (Spherical Error Probable, 50 percentage), in meters
%             (5)  CEP (Circular Error Probable, 50 percentage), in meters
%             (6)  LEP (Linear Error Probable, 50 percentage), in meters
%             (7)  Time Error (50 percentage), in nanoseconds
%             (8)  3-D (Spherical) Position Error (95 percentage), in meters
%             (9)  2-D (Horizontal) Position Error (95 percentage), in meters
%             (10) Actual 2-D (Horizontal) Position Error (95 percentage), in meters
%             (11) Vertical Position Error (95 percentage), in meters
%             (12) Actual Vertical Position Error (95 percentage), in meters
%             (13) Time Error (95 percentage), in nanoseconds
%             (14) Actual Time Error (95 percentage), in nanoseconds
%  Remarks:
%  1) For 2-D Horizontal Position Error (95 percentage) the real percentage is in 
%     the range of 95.4% to 98.2%. The "Actual" is adjusted for a circular distribution.
%  2) For Vertical Position Error (95 percentage) and Time Error (95 percentage) the
%     real percentage is 95.4% rather than 95%. The "Actual" quantities are adjusted
%     for this difference.
%  Last update:  01/17/01
%  Copyright (C) 1996-01 by LL Consulting. All Rights Reserved.

clear 
yes = 'y';

disp('   ');
answer1 = input('Do you want to use the default data set? (y/n)[y] --> ','s');
if isempty(answer1)
   answer1 = yes;
end   
disp('   ');
if (strcmp(answer1,yes) == 1)
%  Default data  (C/A, single frequency, state 5, no SA)
   space_segment = 1.9;
	control_segment = 3.5;
	tropo = 2.;
	iono = 5.;
	multipath = 1.4;
	pr_error = 3.;
	pdop = 2.18;
	hdop = 1.36;
	vdop = 1.7;
	tdop = 0.95;
else
   space_segment = input('Enter space segment error, in meters (1-sigma) -->  ');
   control_segment = input('Enter control segment error, in meters (1-sigma) -->  ');
   tropo = input('Enter tropo error, in meters (1-sigma) -->  ');
   iono = input('Enter iono error, in meters (1-sigma) -->  ');
   multipath = input('Enter multipath error, in meters (1-sigma) -->  ');
   pr_error = input('Enter receiver (pseudorange) error, in meters (1-sigma) -->  ');
   pdop = input('Enter PDOP value -->  ');
   hdop = input('Enter HDOP value -->  ');
   vdop = input('Enter VDOP value -->  ');
   tdop = input('Enter TDOP value -->  ');
   disp('  ');
end

%  Computation of error budget quantities

ure = sqrt(space_segment^2 + control_segment^2);
uee = sqrt(tropo^2 + iono^2 + multipath^2 + pr_error^2);
uere = sqrt(ure^2 + uee^2);

sep = 0.8881 * pdop * uere;
cep = 0.8325 * hdop * uere;
lep = 0.6745 * vdop * uere;
spherical95 = 1.614 * pdop * uere;
herror95 = 2. * hdop * uere;
true_herror95 = 1.7308 * hdop * uere;
verror95 = 2. * vdop * uere;
true_verror95 = 0.995807 * verror95;
terror50 = 0.6745 * 3.3 * tdop * uere;
terror95 = 2. * 3.3 * tdop * uere;
true_terror95 = 0.995807 * terror95;

%  Save computed results into an external file or display on screen

disp('Enter the output desired (output file or on screen)');
answer2 = input('Do you want to display the results on screen? (y/n)[y] --> ','s');
disp('  ');
if isempty(answer2)
   answer2 = yes;
end   
disp('   ');
if (strcmp(answer2,yes) == 1)
   f2 = 1;          %  on screen
else
   f2 = input('Specify the output filename -->  ','s');
   disp('   ');
end

%  Display/save the results

fprintf(f2,'\n****************************************************************************\n');
fprintf(f2,'\n*****                      COMPUTATION OF ERROR BUDGET                 *****\n');
fprintf(f2,'\n****************************************************************************\n');
fprintf(f2,'\n*****                            Input data                           ******\n');
fprintf(f2,'\nSpace space segment error (meters, 1-sigma)      = %7.3f\n',space_segment);
fprintf(f2,'Space control segment error (meters, 1-sigma)    = %7.3f\n',control_segment);
fprintf(f2,'User segmnent, tropo error (meters, 1-sigma)     = %7.3f\n',tropo);
fprintf(f2,'User segmnent, iono error (meters, 1-sigma)      = %7.3f\n',iono);
fprintf(f2,'User segmnent, multipath error (meters, 1-sigma) = %7.3f\n',multipath);
fprintf(f2,'User segmnent, receiver error (meters, 1-sigma)  = %7.3f\n\n',pr_error);
fprintf(f2,'PDOP  = %8.4f\n',pdop);
fprintf(f2,'HDOP  = %8.4f\n',hdop);
fprintf(f2,'VDOP  = %8.4f\n',vdop);
fprintf(f2,'TDOP  = %8.4f\n\n',tdop);
fprintf(f2,'*****                      Results by using XEBUDGET                  ******\n\n');
fprintf(f2,'URE (User Range Error), in meters              = %8.4f\n',ure);
fprintf(f2,'UEE (User Equipment Error), in meters          = %8.4f\n',uee);
fprintf(f2,'UERE (User Equivalent Range Error), in meters  = %8.4f\n\n',uere);
fprintf(f2,'SEP (Spherical Error Probable), 3-D  50 percentage, in meters   = %8.4f\n',sep);
fprintf(f2,'CEP (Circular Error Probable, 2-D  50 percentage, in meters     = %8.4f\n',cep);
fprintf(f2,'LEP (Linear Error Probable), Vertical 50 percentage, in meters  = %8.4f\n',lep);
fprintf(f2,'Time Error (50 percentage), in nanoseconds        = %7.3f\n\n',terror50);
fprintf(f2,'3-D (Spherical) Position Error (95 percentage), in meters  = %7.3f\n',...
            spherical95);
fprintf(f2,'2-D (Horizontal) Position Error (95 percentage), in meters        = %7.3f\n',...
            herror95);
fprintf(f2,'Actual 2-D (Horizontal) Position Error (95 percentage), in meters = %7.3f\n',...
    			true_herror95);
fprintf(f2,'Vertical Position Error (95 percentage), in meters        = %7.3f\n',verror95);
fprintf(f2,'Actual Vertical Position Error (95 percentage), in meters = %7.3f\n',...
            true_verror95);
fprintf(f2,'Time Error (95 percentage), in nanoseconds        = %7.3f\n',terror95);
fprintf(f2,'Actual Time Error (95 percentage), in nanoseconds = %7.3f\n',true_terror95);      
fprintf(f2,'\n****************************************************************************\n');

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