subroutine decode65a(dd,npts,newdat,nqd,f0,nflip,mode65,ntrials, & naggressive,ndepth,mycall,hiscall,hisgrid,nexp_decode,sync2, & a,dt,nft,qual,nhist,nsmo,decoded) ! Apply AFC corrections to a candidate JT65 signal, then decode it. use jt65_mod use timer_module, only: timer parameter (NMAX=60*12000) !Samples per 60 s real*4 dd(NMAX) !92 MB: raw data from Linrad timf2 complex cx(NMAX/8) !Data at 1378.125 sps complex cx1(NMAX/8) !Data at 1378.125 sps, offset by 355.3 Hz complex c5x(NMAX/32) !Data at 344.53125 Hz complex c5a(512) real s2(66,126) real a(5) logical first character decoded*22,decoded_best*22 character mycall*12,hiscall*12,hisgrid*6 data first/.true./,jjjmin/1000/,jjjmax/-1000/ data nhz0/-9999999/ save ! Mix sync tone to baseband, low-pass filter, downsample to 1378.125 Hz call timer('filbig ',0) call filbig(dd,npts,f0,newdat,cx,n5,sq0) if(mode65.eq.4) call filbig(dd,npts,f0+355.297852,newdat,cx1,n5,sq0) call timer('filbig ',1) ! NB: cx has sample rate 12000*77125/672000 = 1378.125 Hz ! Find best DF, drift, curvature, and DT. Start by downsampling to 344.53125 Hz call timer('fil6521 ',0) call fil6521(cx,n5,c5x,n6) call timer('fil6521 ',1) fsample=1378.125/4. call timer('afc65b ',0) ! Best fit for DF, drift, banana-coefficient, and dt. fsample = 344.53125 S/s dtbest=dt call afc65b(c5x,n6,fsample,nflip,a,ccfbest,dtbest) call timer('afc65b ',1) dtbest=dtbest+0.003628 ! remove decimation filter and coh. integrator delay dt=dtbest !return new, improved estimate of dt sync2=3.7e-4*ccfbest/sq0 !Constant is empirical if(mode65.eq.4) cx=cx1 ! Apply AFC corrections to the time-domain signal ! Now we are back to using the 1378.125 Hz sample rate, enough to ! accommodate the full JT65C bandwidth. a(3)=0 call timer('twkfreq ',0) call twkfreq65(cx,n5,a) call timer('twkfreq ',1) ! Compute spectrum for each symbol. nsym=126 nfft=512 df=1378.125/nfft j=int(dtbest*1378.125) call timer('sh_ffts ',0) c5a=cmplx(0.0,0.0) do k=1,nsym do i=1,nfft j=j+1 if(j.ge.1 .and. j.le.NMAX/8) then c5a(i)=cx(j) else c5a(i)=0. endif enddo call four2a(c5a,nfft,1,1,1) do i=1,512 jj=i if(i.gt.256) jj=i-512 s1(jj,k)=real(c5a(i))**2 + aimag(c5a(i))**2 enddo enddo call timer('sh_ffts ',1) call timer('dec65b ',0) qualbest=0. maxsmo=0 if(mode65.eq.2) maxsmo=5 if(mode65.eq.4) maxsmo=10 nn=0 do ismo=0,maxsmo if(ismo.gt.0) then do j=1,126 call smo121(s1(-255,j),512) if(j.eq.1) nn=nn+1 if(nn.ge.4) then call smo121(s1(-255,j),512) if(j.eq.1) nn=nn+1 endif enddo endif do i=1,66 jj=i if(mode65.eq.2) jj=2*i-1 if(mode65.eq.4) then ff=4*(i-1)*df - 355.297852 jj=nint(ff/df)+1 endif s2(i,1:126)=s1(jj,1:126) enddo call decode65b(s2,nflip,mode65,ntrials,naggressive,ndepth, & mycall,hiscall,hisgrid,nexp_decode,nqd,nft,qual,nhist,decoded) if(nft.eq.1) then nsmo=ismo exit else if(nft.eq.2) then !### Should also deal with nft=2 solutions if(qual.gt.qualbest) then decoded_best=decoded qualbest=qual nnbest=nn nsmobest=ismo endif ! print*,'A',nn,ndepth,ntrials,ismo,qual,decoded endif enddo if(nft.eq.2) then decoded=decoded_best qual=qualbest nsmo=nsmobest param(9)=nsmo endif call timer('dec65b ',1) return end subroutine decode65a