2021-04-09 08:57:41 -04:00
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subroutine qra64b(nutc,nqd,fcenter,nfcal,nfsample,ikhz,mousedf,ntol,xpol, &
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mycall_12,hiscall_12,hisgrid_6,mode64,nwrite_qra64)
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parameter (MAXFFT1=5376000) !56*96000
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parameter (MAXFFT2=336000) !56*6000 (downsampled by 1/16)
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complex ca(MAXFFT1),cb(MAXFFT1) !FFTs of raw x,y data
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complex cx(0:MAXFFT2-1),cy(0:MAXFFT2-1)
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logical xpol
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real*8 fcenter
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character*12 mycall_12,hiscall_12
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character*6 hisgrid_6
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common/cacb/ca,cb
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data nzap/3/
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open(17,file='red.dat',status='unknown')
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nfft1=MAXFFT1
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nfft2=MAXFFT2
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df=96000.0/NFFT1
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if(nfsample.eq.95238) then
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nfft1=5120000
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nfft2=322560
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df=96000.0/nfft1
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endif
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nh=nfft2/2
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ikhz0=nint(1000.0*(fcenter-int(fcenter)))
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k0=((ikhz-ikhz0+48.0+1.27)*1000.0+nfcal)/df
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if(k0.lt.nh .or. k0.gt.nfft1-nh) go to 900
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fac=1.0/nfft2
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cx(0:nh)=ca(k0:k0+nh)
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cx(nh+1:nfft2-1)=ca(k0-nh+1:k0-1)
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cx=fac*cx
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if(xpol) then
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cy(0:nh)=cb(k0:k0+nh)
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cy(nh+1:nfft2-1)=cb(k0-nh+1:k0-1)
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cy=fac*cy
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endif
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! Here cx and cy (if xpol) are frequency-domain data around the selected
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! QSO frequency, taken from the full-length FFT computed in filbig().
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! Values for fsample, nfft1, nfft2, df, and the downsampled data rate
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! are as follows:
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! fSample nfft1 df nfft2 fDownSampled
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! (Hz) (Hz) (Hz)
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!----------------------------------------------------
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! 96000 5376000 0.017857143 336000 6000.000
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! 95238 5120000 0.018601172 322560 5999.994
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! write(60) cx,cy,nutc,nqd,ikhz,mousedf,ntol,xpol,mycall_12, &
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! hiscall_12,hisgrid_6
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if(nzap.gt.0) call qra64zap(cx,cy,xpol,nzap)
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! Transform back to time domain with sample rate 6000 Hz.
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call four2a(cx,nfft2,1,-1,1)
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call four2a(cy,nfft2,1,-1,1)
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call qra64c(cx,cy,nutc,nqd,ikhz,mousedf,ntol,xpol,mycall_12, &
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hiscall_12,hisgrid_6,mode64,nwrite_qra64)
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close(17)
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900 return
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end subroutine qra64b
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