subroutine get_fst4_bitmetrics(cd,nss,hmod,nmax,nhicoh,bitmetrics,s4,badsync) include 'fst4_params.f90' complex cd(0:NN*nss-1) complex cs(0:3,NN) complex csymb(nss) complex, allocatable, save :: c1(:,:) ! ideal waveforms, 20 samples per symbol, 4 tones complex cp(0:3) ! accumulated phase shift over symbol types 0:3 complex csum,cterm integer isyncword1(0:7),isyncword2(0:7) integer graymap(0:3) integer ip(1) integer hmod logical one(0:65535,0:15) ! 65536 8-symbol sequences, 16 bits logical first logical badsync real bitmetrics(2*NN,4) real s2(0:65535) real s4(0:3,NN) data isyncword1/0,1,3,2,1,0,2,3/ data isyncword2/2,3,1,0,3,2,0,1/ data graymap/0,1,3,2/ data first/.true./,nss0/-1/ save first,one,cp,nss0 if(nss.ne.nss0 .and. allocated(c1)) deallocate(c1) if(first .or. nss.ne.nss0) then allocate(c1(nss,0:3)) one=.false. do i=0,65535 do j=0,15 if(iand(i,2**j).ne.0) one(i,j)=.true. enddo enddo twopi=8.0*atan(1.0) dphi=twopi*hmod/nss do itone=0,3 dp=(itone-1.5)*dphi phi=0.0 do j=1,nss c1(j,itone)=cmplx(cos(phi),sin(phi)) phi=mod(phi+dp,twopi) enddo cp(itone)=cmplx(cos(phi),sin(phi)) enddo first=.false. endif do k=1,NN i1=(k-1)*NSS csymb=cd(i1:i1+NSS-1) do itone=0,3 cs(itone,k)=sum(csymb*conjg(c1(:,itone))) enddo s4(0:3,k)=abs(cs(0:3,k)) enddo ! Sync quality check is1=0 is2=0 is3=0 is4=0 is5=0 badsync=.false. ibmax=0 do k=1,8 ip=maxloc(s4(:,k)) if(isyncword1(k-1).eq.(ip(1)-1)) is1=is1+1 ip=maxloc(s4(:,k+38)) if(isyncword2(k-1).eq.(ip(1)-1)) is2=is2+1 ip=maxloc(s4(:,k+76)) if(isyncword1(k-1).eq.(ip(1)-1)) is3=is3+1 ip=maxloc(s4(:,k+114)) if(isyncword2(k-1).eq.(ip(1)-1)) is4=is4+1 ip=maxloc(s4(:,k+152)) if(isyncword1(k-1).eq.(ip(1)-1)) is5=is5+1 enddo nsync=is1+is2+is3+is4+is5 !Number of correct hard sync symbols, 0-40 badsync=.false. if(nsync .lt. 16) then badsync=.true. return endif bitmetrics=0.0 do nseq=1,nmax !Try coherent sequences of 1, 2, and 4 symbols if(nseq.eq.1) nsym=1 if(nseq.eq.2) nsym=2 if(nhicoh.eq.0) then if(nseq.eq.3) nsym=3 if(nseq.eq.4) nsym=4 else if(nseq.eq.3) nsym=4 if(nseq.eq.4) nsym=8 endif nt=4**nsym do ks=1,NN-nsym+1,nsym s2=0 do i=0,nt-1 csum=0 cterm=1 do j=0,nsym-1 ntone=mod(i/4**(nsym-1-j),4) csum=csum+cs(graymap(ntone),ks+j)*cterm cterm=cterm*conjg(cp(graymap(ntone))) enddo s2(i)=abs(csum)**2 enddo ipt=1+(ks-1)*2 if(nsym.eq.1) ibmax=1 if(nsym.eq.2) ibmax=3 if(nsym.eq.3) ibmax=5 if(nsym.eq.4) ibmax=7 if(nsym.eq.8) ibmax=15 do ib=0,ibmax bm=maxval(s2(0:nt-1),one(0:nt-1,ibmax-ib)) - & maxval(s2(0:nt-1),.not.one(0:nt-1,ibmax-ib)) if(ipt+ib.gt.2*NN) cycle bitmetrics(ipt+ib,nseq)=bm enddo enddo enddo call normalizebmet(bitmetrics(:,1),2*NN) call normalizebmet(bitmetrics(:,2),2*NN) call normalizebmet(bitmetrics(:,3),2*NN) call normalizebmet(bitmetrics(:,4),2*NN) return end subroutine get_fst4_bitmetrics