subroutine get_ft4s_bitmetrics(cd,hmod,bitmetrics,badsync) include 'ft4s_params.f90' parameter (NSS=20) complex cd(0:NN*NSS-1) complex cs(0:3,NN) complex csymb(NSS) complex c1(NSS,0:3) ! ideal waveforms, 20 samples per symbol, 4 tones complex ccor(0:3,NN) ! correlations with each ideal waveform, for each symbol complex cp(0:3) ! accumulated phase shift over symbol types 0:3 complex csum,cterm integer icos4a(0:3),icos4b(0:3) integer icos4c(0:3),icos4d(0:3) integer icos4e(0:3),icos4f(0:3) integer graymap(0:3) integer ip(1) 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 icos4a/0,1,3,2/ data icos4b/1,0,2,3/ data icos4c/2,3,1,0/ data icos4d/3,2,0,1/ data icos4e/0,2,3,1/ data icos4f/1,2,0,3/ data graymap/0,1,3,2/ data first/.true./ save first,one,c1,cp if(first) then 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 is6=0 badsync=.false. ibmax=0 do k=1,4 ip=maxloc(s4(:,k)) if(icos4a(k-1).eq.(ip(1)-1)) is1=is1+1 ip=maxloc(s4(:,k+28)) if(icos4b(k-1).eq.(ip(1)-1)) is2=is2+1 ip=maxloc(s4(:,k+56)) if(icos4c(k-1).eq.(ip(1)-1)) is3=is3+1 ip=maxloc(s4(:,k+84)) if(icos4d(k-1).eq.(ip(1)-1)) is4=is4+1 ip=maxloc(s4(:,k+112)) if(icos4e(k-1).eq.(ip(1)-1)) is5=is5+1 ip=maxloc(s4(:,k+140)) if(icos4f(k-1).eq.(ip(1)-1)) is6=is6+1 enddo nsync=is1+is2+is3+is4+is5+is6 !Number of correct hard sync symbols, 0-24 badsync=.false. ! if(nsync .lt. 8) then ! badsync=.true. ! return ! endif do nseq=4,1,-1 !Try coherent sequences of 1, 2, and 4 symbols if(nseq.eq.1) nsym=1 if(nseq.eq.2) nsym=2 if(nseq.eq.3) nsym=4 if(nseq.eq.4) nsym=8 nt=4**nsym do ks=1,NN-nsym+1,nsym !87+16=103 symbols. 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) enddo ipt=1+(ks-1)*2 if(nsym.eq.1) ibmax=1 if(nsym.eq.2) ibmax=3 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_ft4s_bitmetrics