subroutine demod64a(signal,nadd,mrsym,mrprob, + mr2sym,mr2prob,ntest,nlow) C Demodulate the 64-bin spectra for each of 63 symbols in a frame. C Parameters C nadd number of spectra already summed C mrsym most reliable symbol value C mr2sym second most likely symbol value C mrprob probability that mrsym was the transmitted value C mr2prob probability that mr2sym was the transmitted value implicit real*8 (a-h,o-z) real*4 signal(64,63) real*8 fs(64) integer mrsym(63),mrprob(63),mr2sym(63),mr2prob(63) afac=1.1 * float(nadd)**0.64 scale=255.999 C Compute average spectral value sum=0. do j=1,63 do i=1,64 sum=sum+signal(i,j) enddo enddo ave=sum/(64.*63.) C Compute probabilities for most reliable symbol values do j=1,63 s1=-1.e30 fsum=0. do i=1,64 x=min(afac*signal(i,j)/ave,50.d0) fs(i)=exp(x) fsum=fsum+fs(i) if(signal(i,j).gt.s1) then s1=signal(i,j) i1=i !Most reliable endif enddo s2=-1.e30 do i=1,64 if(i.ne.i1 .and. signal(i,j).gt.s2) then s2=signal(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 sum=0. nlow=0 do j=1,63 sum=sum+mrprob(j) if(mrprob(j).le.5) nlow=nlow+1 enddo ntest=sum/63 return end