mirror of
https://github.com/saitohirga/WSJT-X.git
synced 2024-09-09 06:46:39 -04:00
f5737348fe
git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@6949 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
118 lines
3.6 KiB
Fortran
118 lines
3.6 KiB
Fortran
subroutine sync64(dd,nf1,nf2,nfqso,ntol,maxf1,dtx,f0,jpk,kpk,snrdb,c0)
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parameter (NMAX=60*12000) !Max size of raw data at 12000 Hz
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parameter (NSPS=2304) !Samples per symbol at 4000 Hz
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parameter (NSPC=7*NSPS) !Samples per Costas array
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real dd(NMAX) !Raw data
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real s1(0:NSPC-1) !Power spectrum of Costas 1
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real s2(0:NSPC-1) !Power spectrum of Costas 2
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real s3(0:NSPC-1) !Power spectrum of Costas 3
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real s0(0:NSPC-1) !Sum of s1+s2+s3
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real s0a(0:NSPC-1) !Best synchromized spectrum
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integer icos7(0:6) !Costas 7x7 tones
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integer ipk0(1)
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complex cc(0:NSPC-1) !Costas waveform
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complex c0(0:360000) !Complex spectrum of dd()
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complex c1(0:NSPC-1) !Complex spectrum of Costas 1
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complex c2(0:NSPC-1) !Complex spectrum of Costas 2
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complex c3(0:NSPC-1) !Complex spectrum of Costas 3
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logical first
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data icos7/2,5,6,0,4,1,3/ !Costas 7x7 tone pattern
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data first/.true./
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save
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if(first) then
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twopi=8.0*atan(1.0)
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dfgen=12000.0/6912.0
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k=-1
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phi=0.
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do j=0,6 !Compute complex Costas waveform
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dphi=twopi*icos7(j)*dfgen/4000.0
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do i=1,2304
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phi=phi + dphi
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if(phi.gt.twopi) phi=phi-twopi
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k=k+1
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cc(k)=cmplx(cos(phi),sin(phi))
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enddo
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enddo
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first=.false.
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endif
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npts0=54*12000
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nfft1=672000
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nfft2=nfft1/3
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df1=12000.0/nfft1
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fac=2.0/nfft1
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do i=0,nfft1/2
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c0(i)=fac*cmplx(dd(1+2*i),dd(2+2*i))
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enddo
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call four2a(c0,nfft1,1,-1,0) !Forward r2c FFT
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call four2a(c0,nfft2,1,1,1) !Inverse c2c FFT; c0 is analytic sig
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npts2=npts0/3 !Downsampled complex data length
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nfft3=NSPC
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nh3=nfft3/2
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df3=4000.0/nfft3
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fa=max(nf1,nfqso-ntol)
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fb=min(nf2,nfqso+ntol)
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ia=max(maxf1,nint(fa/df3))
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ib=min(NSPC-1-maxf1,nint(fb/df3))
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iz=ib-ia+1
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snr=0.
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jpk=0
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ja=0
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jb=6*4000
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jstep=200
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ka=-maxf1
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kb=maxf1
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ipk=0
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kpk=0
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do iter=1,2
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do j1=ja,jb,jstep
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j2=j1 + 39*2304
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j3=j1 + 77*2304
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c1=1.e-4*c0(j1:j1+NSPC-1) * conjg(cc)
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call four2a(c1,nfft3,1,-1,1)
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c2=1.e-4*c0(j2:j2+NSPC-1) * conjg(cc)
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call four2a(c2,nfft3,1,-1,1)
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c3=1.e-4*c0(j3:j3+NSPC-1) * conjg(cc)
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call four2a(c3,nfft3,1,-1,1)
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s0=0.
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s1=0.
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s2=0.
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s3=0.
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do i=ia,ib
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freq=i*df3
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s1(i)=real(c1(i))**2 + aimag(c1(i))**2
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s2(i)=real(c2(i))**2 + aimag(c2(i))**2
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s3(i)=real(c3(i))**2 + aimag(c3(i))**2
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enddo
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do k=ka,kb
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s0(ia:ib)=s1(ia-k:ib-k) + s2(ia:ib) + s3(ia+k:ib+k)
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call smo121(s0(ia:ib),iz)
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call averms(s0(ia:ib),iz,14,ave,rms)
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s=(maxval(s0(ia:ib))-ave)/rms
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if(s.gt.snr) then
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jpk=j1
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! s0a=(s0-ave)/rms
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s0a=s0/rms
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snr=s
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dtx=jpk/4000.0 - 1.0
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ipk0=maxloc(s0(ia:ib))
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ipk=ipk0(1)
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f0=(ipk+ia-1)*df3
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kpk=k
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endif
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enddo
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enddo
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ja=max(0,jpk-2*jstep)
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jb=min(336000-NSPC,jpk+2*jstep)
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jstep=10
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enddo
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write(17) ia,ib,s0a(ia:ib) !Save data for red curve
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close(17)
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snrdb=10.0*log10(snr)-39.0
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return
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end subroutine sync64
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