subroutine msk144_decode(id2,npts,nutc,nprint,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 msk144dt(d,npts,ty,yellow,nyel) nyel=min(nyel,20) 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=2*NSPM nbefore=NSPM ! Process ping list (sorted by S/N) from top down. do n=1,nyel ia=ty(n)*12000.0 - nbefore if(ia.lt.1) ia=1 ib=ia + nbefore + 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,msg,freq,nutc,t0) 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))) y=yellow(n)-1.5 nsnr=y*10 ! this should be 10*db (centibels?) if( nsnr .gt. 999 ) nsnr=99 if(nsnr.gt.nsnr0 .and. nline.gt.0) then write(line(nline),1020) nutc,nsnr,t0,nint(freq),msg if(nprint.ne.0) 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