subroutine syncmsk(cdat,npts,jpk,ipk,idf,rmax,snr,metric,decoded) ! Attempt synchronization, and if successful decode using Viterbi algorithm. use iso_c_binding, only: c_loc,c_size_t use packjt use hashing use timer_module, only: timer parameter (NSPM=840,NSAVE=2000) character*85 pchk_file,gen_file complex cdat(npts) !Analytic signal complex cb(72) !Complex waveform for bit-reversed B11 complex cd(0:11,0:3) complex c(0:NSPM-1) !Complex data for one message length complex c2(0:NSPM-1) complex cb3(1:NSPM,3) real r(12000) real rdat(12000) real ss1(12000) real symbol(140) real rdata(140) real rd2(128) real rsave(NSAVE) real xp(29) real pp(12) !Half-sine pulse shape real cbi(72),cbq(72) complex z,z0,z1,z2,z3,cfac integer*1 e1(128) integer*1, target :: d8(13) integer*1 i1hash(4) integer*1 i1 integer*4 i4Msg6BitWords(12) !72-bit message as 6-bit words integer mettab(0:255,0:1) !Metric table for BPSK modulation integer ipksave(NSAVE) integer jpksave(NSAVE) integer indx(NSAVE) integer b11(11) !Barker-11 code character*22 decoded character*72 c72 logical first equivalence (i1,i4) equivalence (ihash,i1hash) data first/.true./ data b11/1,1,1,0,0,0,1,0,0,1,0/ save first,cb,cd,pi,twopi,dt,f0,f1,mettab phi=0. if(first) then pchk_file="peg-128-80-reg3.pchk" gen_file="peg-128-80-reg3.gen" call init_ldpc(trim(pchk_file)//char(0),trim(gen_file)//char(0)) pi=4.0*atan(1.0) do i=1,12 angle=(i-1)*pi/12.0 pp(i)=sin(angle) enddo cbi(1:12)=(2*b11(11)-1)*pp cbi(13:24)=(2*b11(9)-1)*pp cbi(25:36)=(2*b11(7)-1)*pp cbi(37:48)=(2*b11(5)-1)*pp cbi(49:60)=(2*b11(3)-1)*pp cbi(61:72)=(2*b11(1)-1)*pp cbq(1:6)=0.0 cbq(7:18)=(2*b11(10)-1)*pp cbq(19:30)=(2*b11(8)-1)*pp cbq(31:42)=(2*b11(6)-1)*pp cbq(43:54)=(2*b11(4)-1)*pp cbq(55:66)=(2*b11(2)-1)*pp cbq(67:72)=0.0 print*,"cb" do i=1,72 print*,i,cbi(i),cbq(i) cb(i)=complex(cbi(i),cbq(i)) enddo first=.false. endif nfft=NSPM jz=npts-nfft decoded=" " ipk=0 jpk=0 metric=-9999 r=0. open(unit=78,file="blah.txt") call timer('sync1 ',0) do j=1,jz !Find the Barker-11 sync vectors z=0. ss=0. do i=1, 72 ss=ss + real(cdat(j+i-1))**2 + aimag(cdat(j+i-1))**2 z=z + cdat(j+i-1)*conjg(cb(i)) !Signal matching Barker 11 enddo ss=sqrt(ss/72.0)*72.0 r(j)=abs(z)/ss !Goodness-of-fit to Barker 11 ss1(j)=ss write(78,*) j,r(j),ss1(j) enddo z=0 dt=1.0/12000.0 do j=7,jz z=z+(cdat(j)*conjg(cdat(j-6)))**2 enddo fff=(atan2(aimag(z),real(z))-pi)/(4*pi*6*dt) print*,"Frequency error ",fff call timer('sync1 ',1) call timer('sync2 ',0) jz=npts-nfft rmax=0. ! n1=35, n2=69, n3=94 k=0 do j=1,jz !Find best full-message sync if(ss1(j).lt.85.0) cycle r1=r(j) + r(j+282) + r(j+768) ! 6*(12+n1) 6*(24+n1+n2) r2=r(j) + r(j+486) + r(j+1122) ! 6*(12+n2) 6*(24+n2+n3) r3=r(j) + r(j+636) + r(j+918) ! 6*(12+n3) 6*(24+n3+n1) if(r1.gt.rmax) then rmax=r1 jpk=j ipk=1 endif if(r2.gt.rmax) then rmax=r2 jpk=j ipk=2 endif if(r3.gt.rmax) then rmax=r3 jpk=j ipk=3 endif rrmax=max(r1,r2,r3) if(rrmax.gt.1.9) then k=min(k+1,NSAVE) if(r1.eq.rrmax) ipksave(k)=1 if(r2.eq.rrmax) ipksave(k)=2 if(r3.eq.rrmax) ipksave(k)=3 jpksave(k)=j rsave(k)=rrmax endif enddo call timer('sync2 ',1) kmax=k call indexx(rsave,kmax,indx) call timer('sync3 ',0) do kk=1,kmax k=indx(kmax+1-kk) ipk=ipksave(k) jpk=jpksave(k) rmax=rsave(k) c=conjg(cb3(1:NSPM,ipk))*cdat(jpk:jpk+nfft-1) smax=0. dfx=0. idfbest=0 do itry=1,25 idf=itry/2 if(mod(itry,2).eq.0) idf=-idf idf=4*idf twk=idf call tweak1(c,NSPM,-twk,c2) z=sum(c2) if(abs(z).gt.smax) then dfx=twk smax=abs(z) phi=atan2(aimag(z),real(z)) !Carrier phase offset idfbest=idf endif enddo idf=idfbest call tweak1(cdat,npts,-dfx,cdat) cfac=cmplx(cos(phi),-sin(phi)) cdat=cfac*cdat sig=0. ref=0. rdat(1:npts)=cdat iz=11 do k=1,234 !Compute soft symbols j=jpk+6*(k-1) z0=2.0*dot_product(cdat(j:j+iz),cd(0:iz,0)) z1=2.0*dot_product(cdat(j:j+iz),cd(0:iz,1)) z2=2.0*dot_product(cdat(j:j+iz),cd(0:iz,2)) z3=2.0*dot_product(cdat(j:j+iz),cd(0:iz,3)) !### Maybe these should be weighted by yellow() ? if(j+1404+iz.lt.npts) then z0=z0 + dot_product(cdat(j+1404:j+1404+iz),cd(0:iz,0)) z1=z1 + dot_product(cdat(j+1404:j+1404+iz),cd(0:iz,1)) z2=z2 + dot_product(cdat(j+1404:j+1404+iz),cd(0:iz,2)) z3=z3 + dot_product(cdat(j+1404:j+1404+iz),cd(0:iz,3)) endif if(j-1404.ge.1) then z0=z0 + dot_product(cdat(j-1404:j-1404+iz),cd(0:iz,0)) z1=z1 + dot_product(cdat(j-1404:j-1404+iz),cd(0:iz,1)) z2=z2 + dot_product(cdat(j-1404:j-1404+iz),cd(0:iz,2)) z3=z3 + dot_product(cdat(j-1404:j-1404+iz),cd(0:iz,3)) endif sym=max(abs(real(z2)),abs(real(z3))) - max(abs(real(z0)),abs(real(z1))) if(sym.lt.0.0) then phi=atan2(aimag(z0),real(z0)) sig=sig + real(z0)**2 ref=ref + aimag(z0)**2 else phi=atan2(aimag(z1),real(z1)) sig=sig + real(z1)**2 ref=ref + aimag(z1)**2 endif n=k if(ipk.eq.2) n=k+47 if(ipk.eq.3) n=k+128 if(n.gt.234) n=n-234 ibit=0 if(sym.ge.0) ibit=1 symbol(n)=sym enddo snr=db(sig/ref-1.0) ! rdata(1:35)=symbol(12:46) ! rdata(36:104)=symbol(59:127) ! rdata(105:198)=symbol(140:233) ! Re-order the symbols and make them i*1 j=0 do i=1,99 i4=128+rdata(i) !### Should be nint() ??? ### if(i4.gt.255) i4=255 if(i4.lt.0) i4=0 j=j+1 e1(j)=i1 rd2(j)=rdata(i) i4=128+rdata(i+99) if(i4.gt.255) i4=255 if(i4.lt.0) i4=0 j=j+1 e1(j)=i1 rd2(j)=rdata(i+99) enddo ! Decode the message nb1=87 call vit213(e1,nb1,mettab,d8,metric) ihash=nhash(c_loc(d8),int(9,c_size_t),146) ihash=2*iand(ihash,32767) decoded=' ' if(d8(10).eq.i1hash(2) .and. d8(11).eq.i1hash(1)) then write(c72,1012) d8(1:9) 1012 format(9b8.8) read(c72,1014) i4Msg6BitWords 1014 format(12b6.6) call unpackmsg(i4Msg6BitWords,decoded) !Unpack to get msgsent endif if(decoded.ne.' ') exit enddo call timer('sync3 ',1) return end subroutine syncmsk