Basic GPS Concept - Fundamentals of Global Positioning System Receivers: A Software Approach - page 29

for k = 1:3;
gu(k) = gu(k) + dl(k);

%** find new position

end
erro=dl(1)^2+dl(2)^2+dl(3)^2; % find error
for j = 1:nsat;
rao(j)=((gu(1)-sp(1,j))^2+(gu(2)-
sp(2,j))^2+(gu(3)-sp(3,j))^2)^.5; % find new rao
without clock bias

end
end

% ***** Final result in spherical coordinate system *****
xuser = gu(1); yuser = gu(2); zuser = gu(3); bias = bu;

rsp = (xuser^2+yuser^2+zuser^2)^.5; % radius of spherical
earth

% Eq 2.17
Lc = atan(zuser/(xuser^2+yuser^2)^.5); % latitude of sperical
% earth Eq 2.18
lsp = atan(yuser/xuser)*180/pi; % longitude spherical and
flat

% earth Eq 2.19

% ***** Converting to practical earth shape *****

e=1/298.257223563;
Ltemp=Lc;
erro1=1;

while erro1>1e-6; % calculating latitude by Eq. 2.51
L=Lc+e*sin(2*Ltemp);
erro1=abs(Ltemp-L);
Ltemp=L;

end
Lflp=L*180/pi; % latitude of flat earth
re=6378137;
h=rsp-re*(1-e*(sin(L)^2)); % altitude of flat earth
lsp = lsp; % longitude of flat earth
upos = [xuser yuser zuser bias rsp Lflp lsp h]';