Add file needed by msk144d.

git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@6717 ab8295b8-cf94-4d9e-aec4-7959e3be5d79

lib/msk144_decode.f90

@@ -0,0 +1,83 @@
+subroutine msk144_decode(id2,npts,nutc,line)
+
+! Calls the experimental decoder for JTMSK 72ms ldpc messages
+
+  parameter (NMAX=30*12000)
+  parameter (NFFTMAX=512*1024)
+  parameter (NSPM=864)               !Samples per JTMSK long message
+  integer*2 id2(0:NMAX)                !Raw i*2 data, up to T/R = 30 s
+  integer hist(0:32868)
+  real d(0:NMAX)                       !Raw r*4 data
+  real ty(NMAX/512)                    !Ping times
+  real yellow(NMAX/512)
+  complex c(NFFTMAX)                   !Complex (analytic) data
+  complex cdat(24000)                  !Short segments, up to 2 s
+  complex cdat2(24000)
+  character*22 msg,msg0                !Decoded message
+  character*80 line(100)               !Decodes passed back to caller
+  equivalence (hist,d)
+
+  nsnr0=-99
+  nline=0
+  line(1:100)(1:1)=char(0)
+  msg0='                      '
+  msg=msg0
+
+  hist=0
+  do i=0,npts-1
+     n=abs(id2(i))
+     hist(n)=hist(n)+1
+  enddo
+  ns=0
+  do n=0,32768
+     ns=ns+hist(n)
+     if(ns.gt.npts/2) exit
+  enddo
+  fac=1.0/(1.5*n)
+  d(0:npts-1)=fac*id2(0:npts-1)
+!  rms=sqrt(dot_product(d(0:npts-1),d(0:npts-1))/npts)
+!### Would it be better to set median rms to 1.0 ?
+!  d(0:npts-1)=d(0:npts-1)/rms          !Normalize so that rms=1.0
+
+  call mskdt(d,npts,ty,yellow,nyel)
+
+  nyel=min(nyel,100)
+
+  n=log(float(npts))/log(2.0) + 1.0
+  nfft=min(2**n,1024*1024)
+  call analytic(d,npts,nfft,c)         !Convert to analytic signal and filter
+
+  nafter=NSPM
+! Process ping list (sorted by S/N) from top down.
+  do n=1,nyel
+     ia=ty(n)*12000.0 - NSPM/2
+     if(ia.lt.1) ia=1
+     ib=ia + 2*nafter-1
+     if(ib.gt.NFFTMAX) ib=NFFTMAX
+     iz=ib-ia+1
+     cdat2(1:iz)=c(ia:ib)               !Select nlen complex samples
+     t0=ia/12000.0
+     call syncmsk144(cdat2,iz,metric,msg,freq)
+     if(metric.eq.-9999) cycle             !No output if no significant sync
+     if(msg(1:1).ne.' ') then
+!      if(msg.ne.msg0) then
+         nline=nline+1
+         nsnr0=-99
+!      endif
+       y=10.0**(0.1*(yellow(n)-1.5))
+       nsnr=max(-5,nint(db(y)))
+!      if(nsnr.gt.nsnr0 .and. nline.gt.0) then
+!      write(line(nline),1020) nutc,nsnr,t0,nint(freq),msg
+       write(*,1020) nutc,nsnr,t0,nint(freq),msg
+1020   format(i6.6,i4,f5.1,i5,' & ',a22)
+       nsnr0=nsnr
+!      go to 900
+!    endif
+     msg0=msg
+     endif
+  enddo
+
+900 continue
+
+  return
+end subroutine msk144_decode