subroutine demod64a(s3,nadd,afac1,mrsym,mrprob,mr2sym,mr2prob,ntest,nlow) ! Demodulate the 64-bin spectra for each of 63 symbols in a frame. ! Parameters ! nadd number of spectra already summed ! mrsym most reliable symbol value ! mr2sym second most likely symbol value ! mrprob probability that mrsym was the transmitted value ! mr2prob probability that mr2sym was the transmitted value implicit real*8 (a-h,o-z) real*4 s3(64,63),afac1 real*8 fs(64) integer mrsym(63),mrprob(63),mr2sym(63),mr2prob(63) if(nadd.eq.-999) return afac=afac1 * float(nadd)**0.64 scale=255.999 ! Compute average spectral value ave=sum(s3)/(64.*63.) i1=1 !Silence warning i2=1 ! Compute probabilities for most reliable symbol values do j=1,63 s1=-1.e30 fsum=0. do i=1,64 x=min(afac*s3(i,j)/ave,50.d0) fs(i)=exp(x) fsum=fsum+fs(i) if(s3(i,j).gt.s1) then s1=s3(i,j) i1=i !Most reliable endif enddo s2=-1.e30 do i=1,64 if(i.ne.i1 .and. s3(i,j).gt.s2) then s2=s3(i,j) i2=i !Second most reliable endif enddo p1=fs(i1)/fsum !Normalized probabilities p2=fs(i2)/fsum mrsym(j)=i1-1 mr2sym(j)=i2-1 mrprob(j)=scale*p1 mr2prob(j)=scale*p2 enddo nlow=0 do j=1,63 if(mrprob(j).le.5) nlow=nlow+1 enddo ntest=sum(mrprob)/63.0 return end subroutine demod64a