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Progress on jtmsk 72ms messages.
git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@6710 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
This commit is contained in:
Steven Franke
parent
4d0bf9027b
commit
d68062f9d6
@ -39,8 +39,8 @@ program JTMSKsim
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call genmsk144(msg,ichk,msgsent,itone,itype)
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call genmsk144(msg,ichk,msgsent,itone,itype)
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twopi=8.d0*atan(1.d0)
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twopi=8.d0*atan(1.d0)
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dphi0=twopi*1000/12000.0
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dphi0=twopi*(freq-500)/12000.0
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dphi1=twopi*2000/12000.0
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dphi1=twopi*(freq+500)/12000.0
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phi=0.0
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phi=0.0
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indx=0
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indx=0
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do i=1,144
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do i=1,144
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@ -125,7 +125,7 @@ subroutine genmsk144(msg0,ichk,msgsent,i4tone,itype)
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enddo
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enddo
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call ldpc_encode(msgbits,codeword)
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call ldpc_encode(msgbits,codeword)
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write(*,*) 'codeword',codeword
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j=0
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j=0
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do i=1,nsym/2 !Reorder the encoded bits
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do i=1,nsym/2 !Reorder the encoded bits
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j=j+1
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j=j+1
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@ -1,10 +1,10 @@
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subroutine jtmsk_decode(id2,narg,line)
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subroutine jtmsk_decode(id2,narg,line)
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! Decoder for JTMSK mode
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! Calls the experimental decoder for JTMSK 72ms ldpc messages
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parameter (NMAX=30*12000)
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parameter (NMAX=30*12000)
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parameter (NFFTMAX=512*1024)
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parameter (NFFTMAX=512*1024)
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parameter (NSPM=840) !Samples per JTMSK long message
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parameter (NSPM=864) !Samples per JTMSK long message
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integer*2 id2(0:NMAX) !Raw i*2 data, up to T/R = 30 s
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integer*2 id2(0:NMAX) !Raw i*2 data, up to T/R = 30 s
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integer hist(0:32868)
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integer hist(0:32868)
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real d(0:NMAX) !Raw r*4 data
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real d(0:NMAX) !Raw r*4 data
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@ -54,10 +54,9 @@ subroutine jtmsk_decode(id2,narg,line)
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!### Would it be better to set median rms to 1.0 ?
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!### Would it be better to set median rms to 1.0 ?
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! d(0:npts-1)=d(0:npts-1)/rms !Normalize so that rms=1.0
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! d(0:npts-1)=d(0:npts-1)/rms !Normalize so that rms=1.0
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call mskdt(d,npts,ty,yellow,nyel)
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call mskdt(d,npts,ty,yellow,nyel)
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print*,nyel
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! do i=1,nyel
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do i=1,nyel
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! print*,i,ty(i),yellow(i)
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print*,i,ty(i),yellow(i)
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! enddo
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enddo
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nyel=min(nyel,5)
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nyel=min(nyel,5)
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@ -65,17 +64,17 @@ subroutine jtmsk_decode(id2,narg,line)
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nfft=min(2**n,1024*1024)
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nfft=min(2**n,1024*1024)
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call analytic(d,npts,nfft,c) !Convert to analytic signal and filter
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call analytic(d,npts,nfft,c) !Convert to analytic signal and filter
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nbefore=NSPM
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nafter=NSPM
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nafter=4*NSPM
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! Process ping list (sorted by S/N) from top down.
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! Process ping list (sorted by S/N) from top down.
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! do n=1,nyel
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! do n=1,nyel
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do n=1,1
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do n=1,nyel
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ia=ty(n)*12000.0 - nbefore
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ia=ty(n)*12000.0 - NSPM/2
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if(ia.lt.1) ia=1
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if(ia.lt.1) ia=1
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ib=ia + nafter
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ib=ia + 2*nafter-1
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if(ib.gt.NFFTMAX) ib=NFFTMAX
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if(ib.gt.NFFTMAX) ib=NFFTMAX
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iz=ib-ia+1
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iz=ib-ia+1
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cdat2(1:iz)=c(ia:ib) !Select nlen complex samples
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cdat2(1:iz)=c(ia:ib) !Select nlen complex samples
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write(*,*) ty(1),ia,ib,iz
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ja=ia/NSPM + 1
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ja=ia/NSPM + 1
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jb=ib/NSPM
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jb=ib/NSPM
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t0=ia/12000.0
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t0=ia/12000.0
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@ -86,7 +85,7 @@ subroutine jtmsk_decode(id2,narg,line)
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if(abs(idf1).gt.ntol) exit
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if(abs(idf1).gt.ntol) exit
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fpk=idf1 + nrxfreq
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fpk=idf1 + nrxfreq
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call tweak1(cdat2,iz,1500.0-fpk,cdat)
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call tweak1(cdat2,iz,1500.0-fpk,cdat)
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call syncmsk(cdat,iz,jpk,ipk,idf,rmax,snr,metric,msg)
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call syncmsk144(cdat,iz,jpk,ipk,idf,rmax,snr,metric,msg,freq)
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if(metric.eq.-9999) cycle !No output if no significant sync
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if(metric.eq.-9999) cycle !No output if no significant sync
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if(msg(1:1).eq.' ') call jtmsk_short(cdat,iz,narg,tbest,idfpk,msg)
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if(msg(1:1).eq.' ') call jtmsk_short(cdat,iz,narg,tbest,idfpk,msg)
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if(msg(1:1).eq.'<' .and. naggressive.eq.0 .and. &
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if(msg(1:1).eq.'<' .and. naggressive.eq.0 .and. &
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@ -96,15 +95,10 @@ subroutine jtmsk_decode(id2,narg,line)
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nline=nline+1
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nline=nline+1
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nsnr0=-99
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nsnr0=-99
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endif
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endif
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freq=fpk+idf
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t0=(ia+jpk)/12000.0
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t0=(ia+jpk)/12000.0
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y=10.0**(0.1*(yellow(n)-1.5))
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y=10.0**(0.1*(yellow(n)-1.5))
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nsnr=max(-5,nint(db(y)))
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nsnr=max(-5,nint(db(y)))
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if(nsnr.gt.nsnr0 .and. nline.gt.0) then
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if(nsnr.gt.nsnr0 .and. nline.gt.0) then
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call rectify_msk(cdat2(jpk:jpk+NSPM-1),msg,narg(13),freq2)
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freq=freq2
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if(msg(1:1).eq.'<') freq=freq2+idfpk
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!### Check freq values !!!
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write(line(nline),1020) nutc,nsnr,t0,nint(freq),msg
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write(line(nline),1020) nutc,nsnr,t0,nint(freq),msg
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1020 format(i6.6,i4,f5.1,i5,' & ',a22)
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1020 format(i6.6,i4,f5.1,i5,' & ',a22)
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nsnr0=nsnr
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nsnr0=nsnr
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@ -1,4 +1,4 @@
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subroutine syncmsk(cdat,npts,jpk,ipk,idf,rmax,snr,metric,decoded)
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subroutine syncmsk144(cdat,npts,jpk,ipk,idf,rmax,snr,metric,decoded)
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! Attempt synchronization, and if successful decode using Viterbi algorithm.
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! Attempt synchronization, and if successful decode using Viterbi algorithm.
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@ -7,264 +7,252 @@ subroutine syncmsk(cdat,npts,jpk,ipk,idf,rmax,snr,metric,decoded)
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use hashing
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use hashing
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use timer_module, only: timer
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use timer_module, only: timer
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parameter (NSPM=840,NSAVE=2000)
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parameter (NSPM=864,NSAVE=2000)
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character*22 msgreceived
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character*85 pchk_file,gen_file
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character*85 pchk_file,gen_file
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complex cdat(npts) !Analytic signal
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complex cdat(npts) !Analytic signal
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complex cb(72) !Complex waveform for bit-reversed B11
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complex c(NSPM)
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complex cd(0:11,0:3)
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complex ctmp(6000)
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complex c(0:NSPM-1) !Complex data for one message length
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complex cb(42) !Complex waveform for sync word
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complex c2(0:NSPM-1)
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complex csum,cfac,cca,ccb
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complex cb3(1:NSPM,3)
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complex cc(npts)
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real r(12000)
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complex cc1(npts)
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real rdat(12000)
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complex cc2(npts)
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real ss1(12000)
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complex cc3(npts)
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real symbol(140)
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integer s8(8),hardbits(144),hardword(128),unscrambledhardbits(128)
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real rdata(140)
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integer*1, target:: i1Dec8BitBytes(10)
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real rd2(128)
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integer, dimension(1) :: iloc
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real rsave(NSAVE)
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integer*4 i4Msg6BitWords(12) !72-bit message as 6-bit words
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real xp(29)
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integer*4 i4Dec6BitWords(12)
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integer*1 decoded(80)
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integer*1, allocatable :: message(:)
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logical ismask(6000)
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real cbi(42),cbq(42)
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real tonespec(6000)
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real rcw(12)
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real dd(npts)
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real pp(12) !Half-sine pulse shape
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real pp(12) !Half-sine pulse shape
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real cbi(72),cbq(72)
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real*8 dt, df, fs, twopi
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complex z,z0,z1,z2,z3,cfac
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real softbits(144)
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integer*1 e1(128)
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real*8 unscrambledsoftbits(128)
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real lratio(128)
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integer*1, target :: d8(13)
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integer*1, target :: d8(13)
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integer*1 i1hash(4)
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integer*1 i1hash(4)
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integer*1 i1
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integer*1 i1
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integer*4 i4Msg6BitWords(12) !72-bit message as 6-bit words
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integer mettab(0:255,0:1) !Metric table for BPSK modulation
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integer ipksave(NSAVE)
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integer jpksave(NSAVE)
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integer indx(NSAVE)
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integer b11(11) !Barker-11 code
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character*22 decoded
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character*72 c72
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character*72 c72
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logical first
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logical first
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equivalence (i1,i4)
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equivalence (i1,i4)
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equivalence (ihash,i1hash)
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equivalence (ihash,i1hash)
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data first/.true./
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data first/.true./
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data b11/1,1,1,0,0,0,1,0,0,1,0/
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save first,cb,cd,pi,twopi,dt,f0,f1,mettab
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phi=0.
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data s8/0,1,1,1,0,0,1,0/
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save first,cb,cd,pi,twopi,dt,f0,f1
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if(first) then
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if(first) then
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print*,"Initializing ldpc."
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pchk_file="peg-128-80-reg3.pchk"
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pchk_file="peg-128-80-reg3.pchk"
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gen_file="peg-128-80-reg3.gen"
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gen_file="peg-128-80-reg3.gen"
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call init_ldpc(trim(pchk_file)//char(0),trim(gen_file)//char(0))
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call init_ldpc(trim(pchk_file)//char(0),trim(gen_file)//char(0))
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pi=4.0*atan(1.0)
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! define half-sine pulse and raised-cosine edge window
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pi=4d0*datan(1d0)
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twopi=4d0*datan(1d0)
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dt=1.0/12000.0
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do i=1,12
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do i=1,12
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angle=(i-1)*pi/12.0
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angle=(i-1)*pi/12.0
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pp(i)=sin(angle)
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pp(i)=sin(angle)
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rcw(i)=(1-cos(angle))/2
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enddo
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enddo
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cbi(1:12)=(2*b11(11)-1)*pp
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! define the sync word waveform
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cbi(13:24)=(2*b11(9)-1)*pp
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s8=2*s8-1
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cbi(25:36)=(2*b11(7)-1)*pp
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cbq(1:6)=pp(7:12)*s8(1)
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cbi(37:48)=(2*b11(5)-1)*pp
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cbq(7:18)=pp*s8(3)
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cbi(49:60)=(2*b11(3)-1)*pp
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cbq(19:30)=pp*s8(5)
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cbi(61:72)=(2*b11(1)-1)*pp
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cbq(31:42)=pp*s8(7)
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cbq(1:6)=0.0
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cbi(1:12)=pp*s8(2)
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cbq(7:18)=(2*b11(10)-1)*pp
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cbi(13:24)=pp*s8(4)
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cbq(19:30)=(2*b11(8)-1)*pp
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cbi(25:36)=pp*s8(6)
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cbq(31:42)=(2*b11(6)-1)*pp
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cbi(37:42)=pp(1:6)*s8(8)
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cbq(43:54)=(2*b11(4)-1)*pp
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cb=cmplx(cbi,cbq)
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cbq(55:66)=(2*b11(2)-1)*pp
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! print*,"cb"
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cbq(67:72)=0.0
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! do i=1,42
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print*,"cb"
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! print*,i,cbi(i),cbq(i)
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do i=1,72
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! enddo
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print*,i,cbi(i),cbq(i)
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cb(i)=complex(cbi(i),cbq(i))
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enddo
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first=.false.
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first=.false.
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endif
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endif
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nfft=NSPM
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jz=npts-nfft
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decoded=" "
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ipk=0
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jpk=0
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metric=-9999
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r=0.
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open(unit=78,file="blah.txt")
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call timer('sync1 ',0)
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do j=1,jz !Find the Barker-11 sync vectors
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z=0.
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ss=0.
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do i=1, 72
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ss=ss + real(cdat(j+i-1))**2 + aimag(cdat(j+i-1))**2
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z=z + cdat(j+i-1)*conjg(cb(i)) !Signal matching Barker 11
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enddo
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ss=sqrt(ss/72.0)*72.0
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r(j)=abs(z)/ss !Goodness-of-fit to Barker 11
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ss1(j)=ss
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write(78,*) j,r(j),ss1(j)
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enddo
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z=0
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! Coarse carrier frequency sync
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dt=1.0/12000.0
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! look for tones near 2k and 4k in the analytic signal spectrum
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do j=7,jz
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! search range for coarse frequency error is +/- 100 Hz
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z=z+(cdat(j)*conjg(cdat(j-6)))**2
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fs=12000.0
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enddo
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nfft=6000 !using a zero-padded fft to get 2 Hz bins
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fff=(atan2(aimag(z),real(z))-pi)/(4*pi*6*dt)
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df=fs/nfft
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print*,"Frequency error ",fff
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call timer('sync1 ',1)
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call timer('sync2 ',0)
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ctmp=cmplx(0.0,0.0)
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jz=npts-nfft
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ctmp(1:npts)=cdat**2
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rmax=0.
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ctmp(1:12)=ctmp(1:12)*rcw
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! n1=35, n2=69, n3=94
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ctmp(npts-11:npts)=ctmp(npts-11:npts)*rcw(12:1:-1)
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k=0
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call four2a(ctmp,nfft,1,-1,1)
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do j=1,jz !Find best full-message sync
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tonespec=abs(ctmp)**2
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if(ss1(j).lt.85.0) cycle
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ismask=.false.
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r1=r(j) + r(j+282) + r(j+768) ! 6*(12+n1) 6*(24+n1+n2)
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ismask(1901:2101)=.true. ! high tone search window
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r2=r(j) + r(j+486) + r(j+1122) ! 6*(12+n2) 6*(24+n2+n3)
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iloc=maxloc(tonespec,ismask)
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r3=r(j) + r(j+636) + r(j+918) ! 6*(12+n3) 6*(24+n3+n1)
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ihpk=iloc(1)
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if(r1.gt.rmax) then
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ah=tonespec(ihpk)
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rmax=r1
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ismask=.false.
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jpk=j
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ismask(901:1101)=.true. ! window for low tone
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ipk=1
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iloc=maxloc(tonespec,ismask)
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endif
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ilpk=iloc(1)
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if(r2.gt.rmax) then
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al=tonespec(ilpk)
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rmax=r2
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if( ah .ge. al ) then
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jpk=j
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ferr=(ihpk-2001)*df/2.0
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ipk=2
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tot=sum(tonespec(1901:2101))
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endif
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q1=200*ah/(tot-tonespec(ihpk))
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if(r3.gt.rmax) then
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rmax=r3
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jpk=j
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ipk=3
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endif
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rrmax=max(r1,r2,r3)
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if(rrmax.gt.1.9) then
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k=min(k+1,NSAVE)
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if(r1.eq.rrmax) ipksave(k)=1
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if(r2.eq.rrmax) ipksave(k)=2
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if(r3.eq.rrmax) ipksave(k)=3
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jpksave(k)=j
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rsave(k)=rrmax
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endif
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enddo
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call timer('sync2 ',1)
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kmax=k
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call indexx(rsave,kmax,indx)
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||||||
|
|
||||||
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
|
else
|
||||||
phi=atan2(aimag(z1),real(z1))
|
ferr=(ilpk-1001)*df/2.0
|
||||||
sig=sig + real(z1)**2
|
tot=sum(tonespec(901:1101))
|
||||||
ref=ref + aimag(z1)**2
|
q1=200*al/(tot-tonespec(ilpk))
|
||||||
endif
|
endif
|
||||||
n=k
|
fdiff=(ihpk-ilpk)*df
|
||||||
if(ipk.eq.2) n=k+47
|
write(*,*) "Coarse frequency error: ",ferr
|
||||||
if(ipk.eq.3) n=k+128
|
write(*,*) "Tone / avg : ",q1
|
||||||
if(n.gt.234) n=n-234
|
write(*,*) "Tone separation : ",fdiff
|
||||||
ibit=0
|
|
||||||
if(sym.ge.0) ibit=1
|
! remove coarse freq error - should now be within a few Hz
|
||||||
symbol(n)=sym
|
call tweak1(cdat,npts,-(1500+ferr),cdat)
|
||||||
|
|
||||||
|
! correlate with sync word waveform
|
||||||
|
cc=0
|
||||||
|
cc1=0
|
||||||
|
cc2=0
|
||||||
|
cc3=0
|
||||||
|
do i=1,npts-448-41
|
||||||
|
cc1(i)=sum(cdat(i:i+41)*conjg(cb))
|
||||||
|
cc2(i)=sum(cdat(i+56*6:i+56*6+41)*conjg(cb))
|
||||||
enddo
|
enddo
|
||||||
snr=db(sig/ref-1.0)
|
cc=cc1+cc2
|
||||||
|
dd=abs(cc1)*abs(cc2)
|
||||||
|
iloc=maxloc(abs(cc))
|
||||||
|
ic1=iloc(1)
|
||||||
|
iloc=maxloc(dd)
|
||||||
|
ic2=iloc(1)
|
||||||
|
|
||||||
! rdata(1:35)=symbol(12:46)
|
write(*,*) ic1,ic2
|
||||||
! rdata(36:104)=symbol(59:127)
|
ic=ic2
|
||||||
! rdata(105:198)=symbol(140:233)
|
|
||||||
|
|
||||||
! Re-order the symbols and make them i*1
|
open(unit=78,file="blah.txt")
|
||||||
j=0
|
do i=1,npts-448-41
|
||||||
do i=1,99
|
write(78,*) i,abs(cc1(i)),abs(cc2(i)),abs(cc(i)),dd(i)
|
||||||
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
|
enddo
|
||||||
|
close(78)
|
||||||
|
|
||||||
! Decode the message
|
cca=sum(cdat(ic:ic+41)*conjg(cb))
|
||||||
nb1=87
|
ccb=sum(cdat(ic+56*6:ic+56*6+41)*conjg(cb))
|
||||||
call vit213(e1,nb1,mettab,d8,metric)
|
phase0=atan2(imag(cca+ccb),real(cca+ccb))
|
||||||
ihash=nhash(c_loc(d8),int(9,c_size_t),146)
|
cfac=ccb*conjg(cca)
|
||||||
ihash=2*iand(ihash,32767)
|
ferr2=atan2(imag(cfac),real(cfac))/(twopi*56*6*dt)
|
||||||
decoded=' '
|
write(*,*) "Fine frequency error: ",ferr2
|
||||||
if(d8(10).eq.i1hash(2) .and. d8(11).eq.i1hash(1)) then
|
write(*,*) "Coarse Carrier phase : ",phase0
|
||||||
write(c72,1012) d8(1:9)
|
|
||||||
1012 format(9b8.8)
|
f0=1500+ferr+ferr2
|
||||||
read(c72,1014) i4Msg6BitWords
|
write(*,*) "Estimated f0 : ",f0
|
||||||
1014 format(12b6.6)
|
|
||||||
call unpackmsg(i4Msg6BitWords,decoded) !Unpack to get msgsent
|
! Remove fine frequency error
|
||||||
|
call tweak1(cdat,npts,-ferr2,cdat)
|
||||||
|
|
||||||
|
! Estimate final carrier phase
|
||||||
|
cca=sum(cdat(ic:ic+41)*conjg(cb))
|
||||||
|
ccb=sum(cdat(ic+56*6:ic+56*6+41)*conjg(cb))
|
||||||
|
phase0=atan2(imag(cca+ccb),real(cca+ccb))
|
||||||
|
cfac=cmplx(cos(phase0),sin(phase0))
|
||||||
|
cdat=cdat*conjg(cfac)
|
||||||
|
|
||||||
|
open(unit=79,file="cdat.txt")
|
||||||
|
write(*,*) "npts = ",npts
|
||||||
|
do i=1,864
|
||||||
|
ii=ic+i-1
|
||||||
|
if( ii .gt. npts ) then
|
||||||
|
ii=ii-864
|
||||||
endif
|
endif
|
||||||
if(decoded.ne.' ') exit
|
c(i)=cdat(ii)
|
||||||
|
write(79,*) i,real(c(i)),imag(c(i))
|
||||||
enddo
|
enddo
|
||||||
call timer('sync3 ',1)
|
close(79)
|
||||||
|
do i=1,72
|
||||||
|
softbits(2*i-1)=imag(c(1+(i-1)*12))
|
||||||
|
softbits(2*i)=real(c(7+(i-1)*12))
|
||||||
|
enddo
|
||||||
|
hardbits=0
|
||||||
|
do i=1,144
|
||||||
|
if( softbits(i) .ge. 0.0 ) then
|
||||||
|
hardbits(i)=1
|
||||||
|
endif
|
||||||
|
enddo
|
||||||
|
write(*,*) hardbits(1:8)
|
||||||
|
write(*,*) hardbits(57:57+7)
|
||||||
|
|
||||||
|
hardword(1:48)=hardbits(9:9+47)
|
||||||
|
hardword(49:128)=hardbits(65:65+80-1)
|
||||||
|
unscrambledhardbits(1:127:2)=hardword(1:64)
|
||||||
|
unscrambledhardbits(2:128:2)=hardword(65:128)
|
||||||
|
! write(*,*) 'unscrambledhardbits',unscrambledhardbits
|
||||||
|
sav=sum(softbits)/144
|
||||||
|
s2av=sum(softbits*softbits)/144
|
||||||
|
ssig=sqrt(s2av-sav*sav)
|
||||||
|
softbits=softbits/ssig
|
||||||
|
|
||||||
|
sigma=0.65
|
||||||
|
lratio(1:48)=softbits(9:9+47)
|
||||||
|
lratio(49:128)=softbits(65:65+80-1)
|
||||||
|
lratio=exp(2.0*lratio/(sigma*sigma))
|
||||||
|
|
||||||
|
unscrambledsoftbits(1:127:2)=lratio(1:64)
|
||||||
|
unscrambledsoftbits(2:128:2)=lratio(65:128)
|
||||||
|
|
||||||
|
max_iterations=50
|
||||||
|
max_dither=1
|
||||||
|
call ldpc_decode(unscrambledsoftbits, decoded, max_iterations, niterations, max_dither, ndither)
|
||||||
|
write(*,*) 'after decoder ',niterations, ndither
|
||||||
|
|
||||||
|
if( niterations .ge. 0 ) then
|
||||||
|
! The decoder found a codeword - compare decoded hash with calculated
|
||||||
|
|
||||||
|
! Collapse 80 decoded bits to 10 bytes. Bytes 1-9 are the message, bute 10 is the hash
|
||||||
|
do ibyte=1,10
|
||||||
|
itmp=0
|
||||||
|
do ibit=1,8
|
||||||
|
itmp=ishft(itmp,1)+iand(1,decoded((ibyte-1)*8+ibit))
|
||||||
|
enddo
|
||||||
|
i1Dec8BitBytes(ibyte)=itmp
|
||||||
|
enddo
|
||||||
|
|
||||||
|
! Calculate the hash using the first 9 bytes.
|
||||||
|
ihashdec=nhash(c_loc(i1Dec8BitBytes),int(9,c_size_t),146)
|
||||||
|
ihashdec=2*iand(ihashdec,255)
|
||||||
|
|
||||||
|
! Compare calculated hash with received byte 10 - if they agree, keep the message.
|
||||||
|
i1hashdec=ihashdec
|
||||||
|
if( i1hashdec .ne. i1Dec8BitBytes(10) ) then
|
||||||
|
nbadhash=nbadhash+1
|
||||||
|
nhashflag=1
|
||||||
|
endif
|
||||||
|
|
||||||
|
! unpack 72-bit message
|
||||||
|
do ibyte=1,12
|
||||||
|
itmp=0
|
||||||
|
do ibit=1,6
|
||||||
|
itmp=ishft(itmp,1)+iand(1,decoded((ibyte-1)*6+ibit))
|
||||||
|
enddo
|
||||||
|
i4Dec6BitWords(ibyte)=itmp
|
||||||
|
enddo
|
||||||
|
call unpackmsg(i4Dec6BitWords,msgreceived)
|
||||||
|
print*,"Received ",msgreceived
|
||||||
|
endif
|
||||||
|
|
||||||
return
|
return
|
||||||
end subroutine syncmsk
|
|
||||||
|
end subroutine syncmsk144
|
||||||
|
|||||||
Loading…
x
Reference in New Issue
Block a user