function?[pos?el?az?dop]?=?leastSquarePos（satpos?obs?settings）
%Function?calculates?the?Least?Square?Solution.
%
%[pos?el?az?dop]?=?leastSquarePos（satpos?obs?settings）;
%
%???Inputs:
%???????satpos??????-?Satellites?positions?（in?ECEF?system:?[X;?Y;?Z;]?-
%???????????????????one?column?per?satellite）
%???????obs?????????-?Observations?-?the?pseudorange?measurements?to?each
%???????????????????satellite:
%???????????????????（e.g.?[20000000?21000000?....?....?....?....?....]）
%???????settings????-?receiver?settings

nmbOfIterations?=?7;

dtr?????=?pi/180;
pos?????=?zeros（4?1）;
X???????=?satpos;
nmbOfSatellites?=?size（satpos?2）;

A???????=?zeros（nmbOfSatellites?4）;
omc?????=?zeros（nmbOfSatellites?1）;
az??????=?zeros（1?nmbOfSatellites）;
el??????=?az;

%===?Iteratively?find?receiver?position?===================================
for?iter?=?1:nmbOfIterations

????for?i?=?1:nmbOfSatellites
????????if?iter?==?1
????????????%---?Initialize?variables?at?the?first?iteration?--------------
????????????Rot_X?=?X（:?i）;
????????????trop?=?2;
????????else
????????????%---?Update?equations?-----------------------------------------
????????????rho2?=?（X（1?i）?-?pos（1））^2?+?（X（2?i）?-?pos（2））^2?+?...
???????????????????（X（3?i）?-?pos（3））^2;
????????????traveltime?=?sqrt（rho2）?/?settings.c?;

????????????%---?Correct?satellite?position?（do?to?earth?rotation）?--------
????????????Rot_X?=?e_r_corr（traveltime?X（:?i））;

????????????%---?Find?the?elevation?angel?of?the?satellite?----------------
????????????[az（i）?el（i）?dist]?=?topocent（pos（1:3?:）?Rot_X?-?pos（1:3?:））;

????????????if?（settings.useTropCorr?==?1）
????????????????%---?Calculate?tropospheric?correction?--------------------
????????????????trop?=?tropo（sin（el（i）?*?dtr）?...
?????????????????????????????0.0?1013.0?293.0?50.0?0.0?0.0?0.0）;
????????????else
????????????????%?Do?not?calculate?or?apply?the?tropospheric?corrections
????????????????trop?=?0;
????????????end
????????end?%?if?iter?==?1?...?...?else?

????????%---?Apply?the?corrections?----------------------------------------
????????omc（i）?=?（obs（i）?-?norm（Rot_X?-?pos（1:3）?‘fro‘）?-?pos（4）?-?trop）;

????????%---?Construct?the?A?matrix?---------------------------------------
????????A（i?:）?=??[?（-（Rot_X（1）?-?pos（1）））?/?obs（i）?...
?????????????????????（-（Rot_X（2）?-?pos（2）））?/?obs（i）?...
?????????????????????（-（Rot_X（3）?-?pos（3）））?/?obs（i）?...
?????????????????????1?];
????end?%?for?i?=?1:nmbOfSatellites

????%?These?lines?allow?the?code?to?exit?gracefully?in?case?of?any?errors
????if?rank（A）?~=?4
????????pos?????=?zeros（1?4）;
????????return
????end

????%---?Find?position?update?---------------------------------------------
????x???=?A?\?omc;
????
????%---?Apply?position?update?--------------------------------------------
????pos?=?pos?+?x;
????
end?%?for?iter?=?1:nmbOfIterations

pos?=?pos‘;

%===?Calculate?Dilution?Of?Precision?===============

?屬性????????????大小?????日期????時間???名稱
-----------?---------??----------?-----??----

?????文件???????3572??2012-07-24?17:18??leastSquarePos.m

-----------?---------??----------?-----??----

?????????????????3572????????????????????1