mirror of https://github.com/saitohirga/WSJT-X.git
87 lines
2.4 KiB
Fortran
87 lines
2.4 KiB
Fortran
subroutine msk144_decode(id2,npts,nutc,nprint,line)
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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 (NFFTMAX=512*1024)
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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 hist(0:32868)
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real d(0:NMAX) !Raw r*4 data
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real ty(NMAX/512) !Ping times
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real yellow(NMAX/512)
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complex c(NFFTMAX) !Complex (analytic) data
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complex cdat(24000) !Short segments, up to 2 s
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complex cdat2(24000)
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character*22 msg,msg0 !Decoded message
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character*80 line(100) !Decodes passed back to caller
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equivalence (hist,d)
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nsnr0=-99
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nline=0
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line(1:100)(1:1)=char(0)
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msg0=' '
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msg=msg0
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hist=0
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do i=0,npts-1
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n=abs(id2(i))
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hist(n)=hist(n)+1
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enddo
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ns=0
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do n=0,32768
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ns=ns+hist(n)
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if(ns.gt.npts/2) exit
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enddo
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fac=1.0/(1.5*n)
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d(0:npts-1)=fac*id2(0:npts-1)
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! rms=sqrt(dot_product(d(0:npts-1),d(0:npts-1))/npts)
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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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call msk144dt(d,npts,ty,yellow,nyel)
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nyel=min(nyel,20)
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n=log(float(npts))/log(2.0) + 1.0
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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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nafter=2*NSPM
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nbefore=NSPM
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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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ia=ty(n)*12000.0 - nbefore
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if(ia.lt.1) ia=1
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ib=ia + nbefore + nafter - 1
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if(ib.gt.NFFTMAX) ib=NFFTMAX
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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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t0=ia/12000.0
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call syncmsk144(cdat2,iz,msg,freq,nutc,t0)
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if(msg(1:1).ne.' ') 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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! y=10.0**(0.1*(yellow(n)-1.5))
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! nsnr=max(-5,nint(db(y)))
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y=yellow(n)-1.5
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nsnr=y*10 ! this should be 10*db (centibels?)
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if( nsnr .gt. 999 ) nsnr=99
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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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if(nprint.ne.0) write(*,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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msg0=msg
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endif
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enddo
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900 continue
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return
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end subroutine msk144_decode
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