fpbias_g.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

%                             fpbias_g.m
%  Scope:   This MATLAB macro computes the value of a function used to determine
%           the parity bias (pbiasb) for the 5 satellite case with Gaussian 
%           distribution [1].
%  Usage:   xoutput = fpbias_g(x)
%  Description of parameters:
%           x       - input, scalar independent variable 
%           pmd     - input, global constant, probability of missed detection
%           td      - input, global constant, normalized threshold
%           xoutput - output, computed value of the function; when 
%                     x = pbiasb then the value of the expression is 0.  
%  Reference: 
%           [1] Brown, R. G., Chin, G. V., GPS RAIM: Calculation of thresholds 
%               and protection radius using Chi-square methods - A geometric 
%               approach. RTCA Paper No. 491-94/SC159-584, Nov. 1994
%  Remark:  The value of td (fault detection normalized threshold) can be a 
%           priori determined by using the program XFDNT.
%  Last update: 04/12/00
%  Copyright (C) 1998-00 by LL Consulting. All Rights Reserved.

function  xoutput = fpbias_g(x)

global    pmd td

%  Example:  for pfa = 3.33333e-7
%  pmd = 0.001;      %  probability of missed detection
%  td = 5.10364;     %  normalized threshold td (td = sqrt(a), where a is the 
                     %  integration upper limit)

temp = sqrt(2);
temp1 = x/temp;
temp2 = td/temp;
  
xoutput = erf(temp1 + temp2) - erf(temp1 - temp2) - (pmd + pmd);