180 lines
4.9 KiB
Plaintext
180 lines
4.9 KiB
Plaintext
subroutine sync4(dat,jz,ntol,NFreeze,MouseDF,mode,mode4,minwidth, &
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dtx,dfx,snrx,snrsync,ccfblue,ccfred1,flip,width,ps0)
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! Synchronizes JT4 data, finding the best-fit DT and DF.
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parameter (NFFTMAX=2520) !Max length of FFTs
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parameter (NHMAX=NFFTMAX/2) !Max length of power spectra
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parameter (NSMAX=525) !Max number of half-symbol steps
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integer ntol !Range of DF search
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real dat(jz)
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real psavg(NHMAX) !Average spectrum of whole record
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real ps0(450) !Avg spectrum for plotting
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real s2(NHMAX,NSMAX) !2d spectrum, stepped by half-symbols
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real ccfblue(-5:540) !CCF with pseudorandom sequence
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real ccfred(-450:450) !Peak of ccfblue, as function of freq
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real red(-450:450) !Peak of ccfblue, as function of freq
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real ccfred1(-224:224) !Peak of ccfblue, as function of freq
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real tmp(1260)
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integer ipk1(1)
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integer nch(7)
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logical savered
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equivalence (ipk1,ipk1a)
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data nch/1,2,4,9,18,36,72/
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save
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! write(*,3001) 'A',ntol,nfreeze,mousedf,mode,mode4,minwidth
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!3001 format(a1,6i6)
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! Do FFTs of twice symbol length, stepped by half symbols. Note that
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! we have already downsampled the data by factor of 2.
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nsym=207
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nfft=2520
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nh=nfft/2
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nq=nfft/4
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nsteps=jz/nq - 1
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df=0.5*11025.0/nfft
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psavg(1:nh)=0.
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if(mode.eq.-999) width=0. !Silence compiler warning
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do j=1,nsteps !Compute spectrum for each step, get average
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k=(j-1)*nq + 1
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call ps4(dat(k),nfft,s2(1,j))
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psavg(1:nh)=psavg(1:nh) + s2(1:nh,j)
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enddo
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nsmo=min(10*mode4,150)
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call flat1b(psavg,nsmo,s2,nh,nsteps,NHMAX,NSMAX) !Flatten spectra
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if(mode4.ge.9) call smo(psavg,nh,tmp,mode4/4)
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i0=132
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do i=1,450
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ps0(i)=5.0*(psavg(i0+2*i) + psavg(i0+2*i+1) - 2.0)
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enddo
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! Set freq and lag ranges
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famin=200.0 + 3*mode4*df
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fbmax=2700.0 - 3*mode4*df
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fa=famin
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fb=fbmax
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if(NFreeze.eq.1) then
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fa=max(famin,1270.46+MouseDF-ntol)
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fb=min(fbmax,1270.46+MouseDF+ntol)
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else
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fa=max(famin,1270.46+MouseDF-600)
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fb=min(fbmax,1270.46+MouseDF+600)
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endif
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ia=fa/df - 3*mode4 !Index of lowest tone, bottom of range
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ib=fb/df - 3*mode4 !Index of lowest tone, top of range
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i0=nint(1270.46/df)
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irange=450
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if(ia-i0.lt.-irange) ia=i0-irange
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if(ib-i0.gt.irange) ib=i0+irange
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lag1=-5
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lag2=59
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syncbest=-1.e30
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ccfred=0.
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jmax=-1000
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jmin=1000
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do ich=minwidth,7 !Find best width
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kz=nch(ich)/2
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savered=.false.
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do i=ia+kz,ib-kz !Find best frequency channel for CCF
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call xcor4(s2,i,nsteps,nsym,lag1,lag2,ich,mode4,ccfblue,ccf0, &
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lagpk0,flip)
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j=i-i0 + 3*mode4
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if(j.ge.-372 .and. j.le.372) then
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ccfred(j)=ccf0
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jmax=max(j,jmax)
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jmin=min(j,jmin)
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endif
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! Find rms of the CCF, without main peak
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call slope(ccfblue(lag1),lag2-lag1+1,lagpk0-lag1+1.0)
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sync=abs(ccfblue(lagpk0))
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! Find best sync value
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if(sync.gt.syncbest) then
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ipk=i
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lagpk=lagpk0
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ichpk=ich
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syncbest=sync
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savered=.true.
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endif
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enddo
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if(savered) red=ccfred
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enddo
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ccfred=red
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! width=df*nch(ichpk)
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dfx=(ipk-i0 + 3*mode4)*df
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! Peak up in time, at best whole-channel frequency
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call xcor4(s2,ipk,nsteps,nsym,lag1,lag2,ichpk,mode4,ccfblue,ccfmax, &
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lagpk,flip)
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xlag=lagpk
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if(lagpk.gt.lag1 .and. lagpk.lt.lag2) then
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call peakup(ccfblue(lagpk-1),ccfmax,ccfblue(lagpk+1),dx2)
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xlag=lagpk+dx2
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endif
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! Find rms of the CCF, without the main peak
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call slope(ccfblue(lag1),lag2-lag1+1,xlag-lag1+1.0)
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sq=0.
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nsq=0
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do lag=lag1,lag2
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if(abs(lag-xlag).gt.2.0) then
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sq=sq+ccfblue(lag)**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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snrsync=max(0.0,db(abs(ccfblue(lagpk)/rms - 1.0)) - 4.5)
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snrx=-26.
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if(mode4.eq.2) snrx=-25.
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if(mode4.eq.4) snrx=-24.
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if(mode4.eq.9) snrx=-23.
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if(mode4.eq.18) snrx=-22.
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if(mode4.eq.36) snrx=-21.
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if(mode4.eq.72) snrx=-20.
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snrx=snrx + snrsync
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dt=2.0/11025.0
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istart=xlag*nq
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dtx=istart*dt
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ccfred1=0.
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jmin=max(jmin,-224)
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jmax=min(jmax,224)
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do i=jmin,jmax
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ccfred1(i)=ccfred(i)
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enddo
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ipk1=maxloc(ccfred1) - 225
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ns=0
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s=0.
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iw=min(mode4,(ib-ia)/4)
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do i=jmin,jmax
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if(abs(i-ipk1a).gt.iw) then
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s=s+ccfred1(i)
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ns=ns+1
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endif
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enddo
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base=s/ns
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ccfred1=ccfred1-base
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ccf10=0.5*maxval(ccfred1)
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do i=ipk1a,jmin,-1
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if(ccfred1(i).le.ccf10) exit
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enddo
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i1=i
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do i=ipk1a,jmax
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if(ccfred1(i).le.ccf10) exit
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enddo
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width=(i-i1)*df
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return
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end subroutine sync4
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include 'flat1b.f90'
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