Global Positioning System Reference
In-Depth Information
% DECODE2.M decode navigation data in subfram 2 into
ephermeris data
clear angmat navd rymkmat
load d:
\
gps
\
big data
\
srvy8210;
angmat=ang;
ptnumat=transpt;
rymkmat=fintime;
[st navd]=navdat(angmat); %*find naviga data (20ms) & first
angle transition
[points, navdata]=matsubf(navd); %*find start pt of subfram 2
prod 0 1s
nsat=length(points);
for m=1:nsat;
iode2(m,:)=navdata(m,points(m)-1+61:points(m)-1+68);
crs(m)=comp2dec(navdata(m,points(m)-1+84:-
1:points(m)
1+69),-5);
deln(m)=comp2dec(navdata(m,points(m)-1+106:-1:points(m)-
1+91),-43)*pi;
m01=navdata(m,points(m)-1+114:-1:points(m)-1+107);
m02=navdata(m,points(m)-1+144:-1:points(m)-1+121);
m03=[m02 m01];
m0(m)=comp2dec(m03,-31)*pi;
clear m01 m02 m03;
cuc(m)=comp2dec(navdata(m,points(m)-1+166:-1:points(m)-
1+151),-29);
e1=navdata(m,points(m)-1+174:-1:points(m)-1+167);
e2=navdata(m,points(m)-1+204:-1:points(m)-1+181);
e3=[e2 e1];
e(m)=bi2de(e3)*2^(-33);
clear e1 e2 e3;
cus(m)=comp2dec(navdata(m,points(m)-1+226:-1:points(m)-
1+211),-29);
sa1=navdata(m,points(m)-1+234:-1:points(m)-1+227);
sa2=navdata(m,points(m)-1+264:-1:points(m)-1+241);
sa3=[sa2 sa1];
sa(m)=bi2de(sa3)*2^(-19);
clear sa1 sa2 sa3;
toe(m)=bi2de(navdata(m,points(m)-1+286:-1:points(m)-
1+271))*2^4;
end
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