diff --git a/lib/msk144_decode.f90 b/lib/msk144_decode.f90 new file mode 100644 index 000000000..77033beb6 --- /dev/null +++ b/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