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https://github.com/saitohirga/WSJT-X.git
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First working decoder for experimental jtmsk 72ms ldpc-coded messages.
git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@6711 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
This commit is contained in:
Steven Franke
parent
d68062f9d6
commit
374282920c
@ -32,6 +32,8 @@ program JTMSKsim
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read(arg,*) snrdb
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call getarg(5,arg)
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read(arg,*) nfiles
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!sig is the peak amplitude of the ping.
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sig=sqrt(2.0)*10.0**(0.05*snrdb)
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h=default_header(12000,NMAX)
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@ -62,8 +64,7 @@ program JTMSKsim
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endif
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call makepings(pings,NMAX,width,sig)
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! pings=0.0
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! pings(12345:24000)=sig
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do ifile=1,nfiles !Loop over requested number of files
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write(fname,1002) ifile !Output filename
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1002 format('000000_',i4.4)
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@ -75,7 +76,6 @@ program JTMSKsim
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j=mod(j+1,864)
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xx=gran()
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wave(i)=pings(i)*waveform(j) + fac*xx
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! write(*,*) pings(i),fac,waveform(j),wave(j)
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iwave(i)=30.0*wave(i)
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enddo
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@ -51,7 +51,6 @@ subroutine genmsk144(msg0,ichk,msgsent,i4tone,itype)
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save
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if( first ) then
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print*,"Initializing ldpc"
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first=.false.
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nsym=128
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pchk_file="peg-128-80-reg3.pchk"
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@ -86,33 +86,34 @@ subroutine jtmsk_decode(id2,narg,line)
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fpk=idf1 + nrxfreq
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call tweak1(cdat2,iz,1500.0-fpk,cdat)
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call syncmsk144(cdat,iz,jpk,ipk,idf,rmax,snr,metric,msg,freq)
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print*,'returned message :',msg
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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.'<' .and. naggressive.eq.0 .and. &
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narg(13)/8.ne.narg(12)) msg=' '
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if(msg(1:1).ne.' ') then
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if(msg.ne.msg0) then
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! if(msg.ne.msg0) then
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nline=nline+1
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nsnr0=-99
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endif
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! endif
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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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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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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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nsnr0=nsnr
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go to 900
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endif
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! go to 900
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! endif
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msg0=msg
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if(nline.ge.maxlines) go to 900
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! if(nline.ge.maxlines) go to 900
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endif
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enddo
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! print*,'c',nutc,n,nint(yellow(n)-4.0),freq,freq2
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print*,'c',nutc,n,nint(yellow(n)-4.0),freq,freq2
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enddo
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900 continue
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! print*,'d',nutc,n,nint(yellow(n)-4.0),freq,freq2
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print*,'d',nutc,n,nint(yellow(n)-4.0),freq,freq2
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if(line(1)(1:6).eq.' ') line(1)(1:1)=char(0)
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return
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@ -1,4 +1,4 @@
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subroutine syncmsk144(cdat,npts,jpk,ipk,idf,rmax,snr,metric,decoded)
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subroutine syncmsk144(cdat,npts,jpk,ipk,idf,rmax,snr,metric,msgreceived,fest)
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! Attempt synchronization, and if successful decode using Viterbi algorithm.
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@ -22,10 +22,11 @@ subroutine syncmsk144(cdat,npts,jpk,ipk,idf,rmax,snr,metric,decoded)
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integer s8(8),hardbits(144),hardword(128),unscrambledhardbits(128)
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integer*1, target:: i1Dec8BitBytes(10)
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integer, dimension(1) :: iloc
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integer*4 i4Msg6BitWords(12) !72-bit message as 6-bit words
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integer*4 i4Msg6BitWords(12) !72-bit message as 6-bit words
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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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integer*1 i1hashdec
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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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@ -36,14 +37,7 @@ subroutine syncmsk144(cdat,npts,jpk,ipk,idf,rmax,snr,metric,decoded)
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real softbits(144)
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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 i1hash(4)
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integer*1 i1
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character*72 c72
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logical first
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equivalence (i1,i4)
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equivalence (ihash,i1hash)
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data first/.true./
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data s8/0,1,1,1,0,0,1,0/
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@ -57,7 +51,7 @@ subroutine syncmsk144(cdat,npts,jpk,ipk,idf,rmax,snr,metric,decoded)
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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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twopi=8d0*datan(1d0)
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dt=1.0/12000.0
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do i=1,12
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angle=(i-1)*pi/12.0
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@ -141,14 +135,14 @@ subroutine syncmsk144(cdat,npts,jpk,ipk,idf,rmax,snr,metric,decoded)
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iloc=maxloc(dd)
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ic2=iloc(1)
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write(*,*) ic1,ic2
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write(*,*) "Syncs: ic1,ic2 ",ic1,ic2
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ic=ic2
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open(unit=78,file="blah.txt")
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do i=1,npts-448-41
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write(78,*) i,abs(cc1(i)),abs(cc2(i)),abs(cc(i)),dd(i)
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enddo
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close(78)
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! open(unit=78,file="blah.txt")
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! do i=1,npts-448-41
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! write(78,*) i,abs(cc1(i)),abs(cc2(i)),abs(cc(i)),dd(i),abs(cc3(i))
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! enddo
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! close(78)
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cca=sum(cdat(ic:ic+41)*conjg(cb))
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ccb=sum(cdat(ic+56*6:ic+56*6+41)*conjg(cb))
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@ -158,8 +152,8 @@ subroutine syncmsk144(cdat,npts,jpk,ipk,idf,rmax,snr,metric,decoded)
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write(*,*) "Fine frequency error: ",ferr2
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write(*,*) "Coarse Carrier phase : ",phase0
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f0=1500+ferr+ferr2
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write(*,*) "Estimated f0 : ",f0
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fest=1500+ferr+ferr2
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write(*,*) "Estimated f0 : ",fest
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! Remove fine frequency error
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call tweak1(cdat,npts,-ferr2,cdat)
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@ -167,7 +161,11 @@ subroutine syncmsk144(cdat,npts,jpk,ipk,idf,rmax,snr,metric,decoded)
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! Estimate final carrier phase
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cca=sum(cdat(ic:ic+41)*conjg(cb))
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ccb=sum(cdat(ic+56*6:ic+56*6+41)*conjg(cb))
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cfac=ccb*conjg(cca)
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ffin=atan2(imag(cfac),real(cfac))/(twopi*56*6*dt)
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phase0=atan2(imag(cca+ccb),real(cca+ccb))
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write(*,*) "Final freq error: ",ffin
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cfac=cmplx(cos(phase0),sin(phase0))
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cdat=cdat*conjg(cfac)
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@ -192,14 +190,13 @@ subroutine syncmsk144(cdat,npts,jpk,ipk,idf,rmax,snr,metric,decoded)
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hardbits(i)=1
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endif
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enddo
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write(*,*) hardbits(1:8)
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write(*,*) hardbits(57:57+7)
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! write(*,*) hardbits(1:8)
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! write(*,*) hardbits(57:57+7)
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hardword(1:48)=hardbits(9:9+47)
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hardword(49:128)=hardbits(65:65+80-1)
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unscrambledhardbits(1:127:2)=hardword(1:64)
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unscrambledhardbits(2:128:2)=hardword(65:128)
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! write(*,*) 'unscrambledhardbits',unscrambledhardbits
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sav=sum(softbits)/144
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s2av=sum(softbits*softbits)/144
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ssig=sqrt(s2av-sav*sav)
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@ -213,15 +210,18 @@ subroutine syncmsk144(cdat,npts,jpk,ipk,idf,rmax,snr,metric,decoded)
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unscrambledsoftbits(1:127:2)=lratio(1:64)
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unscrambledsoftbits(2:128:2)=lratio(65:128)
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max_iterations=50
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max_dither=1
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max_iterations=20
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max_dither=100
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call ldpc_decode(unscrambledsoftbits, decoded, max_iterations, niterations, max_dither, ndither)
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write(*,*) 'after decoder ',niterations, ndither
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write(*,*) 'Decoder used ',niterations,' and ',ndither,' dither trials.'
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if( niterations .lt. 0 ) then
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msgreceived=' '
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return
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endif
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if( niterations .ge. 0 ) then
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! The decoder found a codeword - compare decoded hash with calculated
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! Collapse 80 decoded bits to 10 bytes. Bytes 1-9 are the message, bute 10 is the hash
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! Collapse 80 decoded bits to 10 bytes. Bytes 1-9 are the message, byte 10 is the hash
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do ibyte=1,10
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itmp=0
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do ibit=1,8
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@ -236,22 +236,19 @@ subroutine syncmsk144(cdat,npts,jpk,ipk,idf,rmax,snr,metric,decoded)
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! Compare calculated hash with received byte 10 - if they agree, keep the message.
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i1hashdec=ihashdec
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if( i1hashdec .ne. i1Dec8BitBytes(10) ) then
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nbadhash=nbadhash+1
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nhashflag=1
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endif
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write(*,*) "Hashes",i1hashdec,i1Dec8BitBytes(10)
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! unpack 72-bit message
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do ibyte=1,12
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itmp=0
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do ibit=1,6
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itmp=ishft(itmp,1)+iand(1,decoded((ibyte-1)*6+ibit))
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enddo
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i4Dec6BitWords(ibyte)=itmp
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enddo
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call unpackmsg(i4Dec6BitWords,msgreceived)
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print*,"Received ",msgreceived
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endif
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if( i1hashdec .eq. i1Dec8BitBytes(10) ) then
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! Good hash --- unpack 72-bit message
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do ibyte=1,12
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itmp=0
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do ibit=1,6
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itmp=ishft(itmp,1)+iand(1,decoded((ibyte-1)*6+ibit))
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enddo
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i4Dec6BitWords(ibyte)=itmp
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enddo
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call unpackmsg(i4Dec6BitWords,msgreceived)
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endif
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return
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