%
satPositions =[654521.924219358,-16672583.5535756,-18808700.1235432,-5625385.49668232;...
               -26410472.714435,15211201.3079099,-7290186.59129119,16770256.8394436;...
               3463374.83499896,-13989910.5530641,17255070.2946831,-19831374.5989722];
[x y z]=llh2xyz(21,105,0)
userxyz=[x y z];
speedOfLight=299792458;
lengthOfChips=speedOfLight/1.023e6;
for i=1:4
    dist(i)=norm(userxyz-satPositions(:,i)')/;
end;