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https://github.com/saitohirga/WSJT-X.git
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318 lines
8.8 KiB
Fortran
318 lines
8.8 KiB
Fortran
subroutine q65_sync(nutc,iwave,nmax,mode_q65,codewords,ncw,nsps,nfqso,ntol, &
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xdt,f0,snr1,dat4,snr2,id1)
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! Detect and align with the Q65 sync vector, returning time and frequency
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! offsets and SNR estimate.
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! Input: iwave(0:nmax-1) Raw data
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! mode_q65 Tone spacing 1 2 4 8 16 (A-E)
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! nsps Samples per symbol at 12000 Sa/s
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! nfqso Target frequency (Hz)
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! ntol Search range around nfqso (Hz)
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! Output: xdt Time offset from nominal (s)
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! f0 Frequency of sync tone
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! snr1 Relative SNR of sync signal
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use packjt77
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parameter (NSTEP=8) !Step size nsps/NSTEP
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parameter (LN=2176*63) !LN=LL*NN; LL=64*(mode_q65+2), NN=63
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integer*2 iwave(0:nmax-1) !Raw data
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integer isync(22) !Indices of sync symbols
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integer itone(85)
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integer codewords(63,64)
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integer dat4(13)
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integer ijpk(2)
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logical unpk77_success
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character*77 c77,decoded*37
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real, allocatable :: s1(:,:) !Symbol spectra, 1/8-symbol steps
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real, allocatable :: s3(:,:) !Data-symbol energies s3(LL,63)
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real, allocatable :: ccf(:,:) !CCF(freq,lag)
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! real, allocatable :: ccfcw(:) ! Method 2
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! real, allocatable :: ccfpk(:) ! Method 2
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! integer cwpk(1) ! Method 2
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! integer, allocatable :: cwtone(:,:) ! Method 2
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real, allocatable :: ccf1(:) !CCF(freq) at best lag
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real s3prob(0:63,63) !Symbol-value probabilities
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real sync(85) !sync vector
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complex, allocatable :: c0(:) !Complex spectrum of symbol
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data isync/1,9,12,13,15,22,23,26,27,33,35,38,46,50,55,60,62,66,69,74,76,85/
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data sync(1)/99.0/
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save sync
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id1=0
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dat4=0
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LL=64*(2+mode_q65)
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nfft=nsps
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df=12000.0/nfft !Freq resolution = baud
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istep=nsps/NSTEP
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iz=5000.0/df !Uppermost frequency bin, at 5000 Hz
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txt=85.0*nsps/12000.0
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jz=(txt+1.0)*12000.0/istep !Number of quarter-symbol steps
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if(nsps.ge.6912) jz=(txt+2.0)*12000.0/istep !For TR 60 s and higher
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ia=ntol/df
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allocate(s1(iz,jz))
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allocate(s3(-64:LL-65,63))
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allocate(c0(0:nfft-1))
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allocate(ccf(-ia:ia,-53:214))
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allocate(ccf1(-ia:ia))
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! allocate(ccfcw(1:ncw)) ! Method 2
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! allocate(ccfpk(1:ncw)) ! Method 2
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! allocate(cwtone(ncw,85)) ! Method 2
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if(sync(1).eq.99.0) then !Generate the sync vector
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sync=-22.0/63.0 !Sync tone OFF
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do k=1,22
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sync(isync(k))=1.0 !Sync tone ON
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enddo
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endif
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fac=1/32767.0
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do j=1,jz !Compute symbol spectra at step size
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ia=(j-1)*istep
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ib=ia+nsps-1
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k=-1
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do i=ia,ib,2 !Load iwave data into complex array c0, for r2c FFT
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xx=iwave(i)
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yy=iwave(i+1)
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k=k+1
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c0(k)=fac*cmplx(xx,yy)
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enddo
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c0(k+1:)=0.
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call four2a(c0,nfft,1,-1,0) !r2c FFT
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do i=1,iz
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s1(i,j)=real(c0(i))**2 + aimag(c0(i))**2
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enddo
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! For large Doppler spreads, should we smooth the spectra here?
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! call smo121(s1(1:iz,j),iz)
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enddo
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i0=nint(nfqso/df) !Target QSO frequency
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call pctile(s1(i0-64:i0-65+LL,1:jz),LL*jz,40,base)
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s1=s1/base
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! Apply fast AGC
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s1max=20.0 !Empirical choice
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do j=1,jz !### Maybe wrong way? ###
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smax=maxval(s1(i0-64:i0-65+LL,j))
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if(smax.gt.s1max) s1(i0-64:i0-65+LL,j)=s1(i0-64:i0-65+LL,j)*s1max/smax
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enddo
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dtstep=nsps/(NSTEP*12000.0) !Step size in seconds
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ia=ntol/df
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lag1=-1.0/dtstep
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lag2=1.0/dtstep + 0.9999
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j0=0.5/dtstep
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if(nsps.ge.7200) then
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j0=1.0/dtstep !Nominal index for start of signal
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lag2=4.0/dtstep + 0.9999 !Include EME delays
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endif
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if(ncw.lt.1) go to 100
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!######################################################################
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! Try list decoding via "Deep Likelihood".
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! Joe's method
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ipk=0
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jpk=0
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ccf_best=0.
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imsg_best=-1
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do imsg=1,ncw
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i=1
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k=0
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do j=1,85
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if(j.eq.isync(i)) then
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i=i+1
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itone(j)=-1
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else
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k=k+1
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itone(j)=codewords(k,imsg)
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endif
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enddo
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! Compute 2D ccf using all 85 symbols in the list message
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ccf=0.
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do lag=lag1,lag2
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do k=1,85
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j=j0 + NSTEP*(k-1) + 1 + lag
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if(j.ge.1 .and. j.le.jz) then
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do i=-ia,ia
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ii=i0+mode_q65*itone(k)+i
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ccf(i,lag)=ccf(i,lag) + s1(ii,j)
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enddo
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endif
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enddo
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enddo
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ccfmax=maxval(ccf)
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if(ccfmax.gt.ccf_best) then
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ccf_best=ccfmax
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ijpk=maxloc(ccf)
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ipk=ijpk(1)-ia-1
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jpk=ijpk(2)-53-1
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f0=nfqso + ipk*df
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xdt=jpk*dtstep
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imsg_best=imsg
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endif
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enddo ! imsg
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! Nico's Method 2
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! Computes the ccf in a different order so that
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! we can see what the ccfs of the list looked like
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! on ccfmax
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! Compute codeword tones
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! cwtone = 0
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! do imsg=1,ncw
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! i=1
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! k=0
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! do j=1,85
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! if(j.eq.isync(i)) then
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! i=i+1
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! cwtone(imsg,j)=-1
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! else
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! k=k+1
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! cwtone(imsg,j)=codewords(k,imsg)
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! endif
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! enddo
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! enddo
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! ipk=0
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! jpk=0
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! ccf_best=0.
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! imsg_best=-1
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! ccf=0.
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! do lag=lag1,lag2
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! do i=-ia,ia
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! ccfcw = 0.
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! do k=1,85
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! j=j0 + NSTEP*(k-1) + 1 + lag
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! if(j.ge.1 .and. j.le.jz) then
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! do imsg=1,ncw
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! ! if we would like to check only non systematic symbols
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! ! uncomment the following if
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! !if (k.gt.18 .or. cwtone(imsg,k).eq.-1) then
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! ii=i0+mode_q65*cwtone(imsg,k)+i
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! ccfcw(imsg)=ccfcw(imsg) + s1(ii,j)
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! !endif
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! enddo
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! endif
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! enddo
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! ccfmax=maxval(ccfcw)
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! ccf(i,lag) = ccfmax
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! if(ccfmax.gt.ccf_best) then
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! ccfpk = ccfcw
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! cwpk = maxloc(ccfpk)
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! imsg_best = cwpk(1)
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! ccf_best = ccfmax
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! endif
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! enddo
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! enddo
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! ccfmax=maxval(ccf)
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! ccf_best=ccfmax
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! ijpk=maxloc(ccf)
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! ipk=ijpk(1)-ia-1
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! jpk=ijpk(2)-53-1
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! f0=nfqso + ipk*df
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! xdt=jpk*dtstep
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ia=i0+ipk-64
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ib=ia+LL-1
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j=j0+jpk-7
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n=0
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do k=1,85
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j=j+8
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if(sync(k).gt.0.0) then
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cycle
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endif
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n=n+1
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if(j.ge.1 .and. j.le.jz) s3(-64:LL-65,n)=s1(ia:ib,j)
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enddo
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nsubmode=0
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if(mode_q65.eq.2) nsubmode=1
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if(mode_q65.eq.4) nsubmode=2
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if(mode_q65.eq.8) nsubmode=3
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if(mode_q65.eq.16) nsubmode=4
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nFadingModel=1
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baud=12000.0/nsps
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isreport = 0;
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do ibw=2,4
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b90=1.72**ibw
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call q65_intrinsics_ff(s3,nsubmode,b90/baud,nFadingModel,s3prob)
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call q65_dec_fullaplist(s3,s3prob,codewords,ncw,esnodb,dat4,plog,irc)
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! Joe's threshold
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! if(irc.ge.0 .and. plog.ge.-255.0) then
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! Nico's threshold
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if (irc.ge.0) then
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! if it is an RRR type or a CQ Mycall grid
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! we accept the fullaplist threshold
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! other cases in the list are reports which
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! are more frequent in the list and then
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! must be filtered with a higher threshold
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if((irc.le.3.0 .or. irc.eq.56.0) .or. plog.ge.-250.0) then
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snr2=esnodb - db(2500.0/baud)
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id1=1
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write(c77,1000) dat4(1:12),dat4(13)/2
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1000 format(12b6.6,b5.5)
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call unpack77(c77,0,decoded,unpk77_success) !Unpack to get msgsent
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open(55,file='fort.55',status='unknown',position='append')
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! Joe's dump
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! write(55,3055) nutc,ibw,xdt,f0,85.0*base,ccfmax,snr2,plog, &
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! irc,trim(decoded)
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!3055 format(i6,i3,6f8.2,i5,2x,a)
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! Nico's dump for Method 2
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! This are the ccfs of the codeword in the list at the
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! ccf peak
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! write(55,3083) ccfpk
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!3083 format(10f6.1)
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! Show also the imsg_best in order to compare it with
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! irc. (Interestingly they are always equal!)
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! write(55,3055) nutc,ibw,xdt,f0,85.0*base,ccfmax,snr2,plog, &
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! irc,(imsg_best-1),trim(decoded)
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!3055 format(i6,i3,6f8.2,2i5,2x,a)
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close(55)
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go to 900
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endif
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endif
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enddo
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!######################################################################
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! Establish xdt, f0, and snr1 using sync symbols (and perhaps some AP symbols)
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100 ccf=0.
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irc=-2
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dat4=0
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ia=ntol/df
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do lag=lag1,lag2
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do k=1,85
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n=NSTEP*(k-1) + 1
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j=n+lag+j0
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if(j.ge.1 .and. j.le.jz) then
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ccf(-ia:ia,lag)=ccf(-ia:ia,lag) + sync(k)*s1(i0-ia:i0+ia,j)
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endif
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enddo
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enddo
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ijpk=maxloc(ccf)
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ipk=ijpk(1)-ia-1
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jpk=ijpk(2)-53-1
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f0=nfqso + ipk*df
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xdt=jpk*dtstep
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sq=0.
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nsq=0
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do j=lag1,lag2
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if(abs(j-jpk).gt.6) then
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sq=sq + ccf(ipk,j)**2
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nsq=nsq+1
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endif
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enddo
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rms=sqrt(sq/nsq)
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smax=ccf(ipk,jpk)
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snr1=smax/rms
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900 return
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end subroutine q65_sync
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