function [out]=mapping_header(datain,length);
data=double(datain);
p(7)=-1;
p(8)=1;
p(9)=-1;
p(10)=-1;
p(11)=-1;
p(12)=-1;
for i=1:(length/50)
    for j=1:50
        sym((i-1)*200+j)=data((i-1)*50+j);
        sym((i-1)*200+101-j)=conj(data((i-1)*50+j));
        sym((i-1)*200+100+j)=p(mod(i+6,127))*data((i-1)*50+j);
        sym((i-1)*200+100+101-j)=p(mod(i+6,127))*conj(data((i-1)*50+j));
    end
end
out=sym;