37 lines
839 B
Fortran
37 lines
839 B
Fortran
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subroutine foxfilt(nslots,nfreq,width,wave)
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parameter (NN=79,ND=58,KK=87,NSPS=4*1920)
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parameter (NWAVE=NN*NSPS,NFFT=614400,NH=NFFT/2)
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real wave(NWAVE)
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real x(NFFT)
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complex cx(0:NH)
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equivalence (x,cx)
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x(1:NWAVE)=wave
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x(NWAVE+1:)=0.
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call four2a(x,NFFT,1,-1,0) !r2c
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df=48000.0/NFFT
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fa=nfreq - 0.5*6.25
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fb=nfreq + 7.5*6.25 + (nslots-1)*60.0
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ia2=nint(fa/df)
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ib1=nint(fb/df)
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ia1=nint(ia2-width/df)
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ib2=nint(ib1+width/df)
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pi=4.0*atan(1.0)
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do i=ia1,ia2
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fil=(1.0 + cos(pi*df*(i-ia2)/width))/2.0
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cx(i)=fil*cx(i)
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enddo
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do i=ib1,ib2
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fil=(1.0 + cos(pi*df*(i-ib1)/width))/2.0
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cx(i)=fil*cx(i)
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enddo
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cx(0:ia1-1)=0.
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cx(ib2+1:)=0.
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call four2a(cx,nfft,1,1,-1) !c2r
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wave=x(1:NWAVE)/nfft
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return
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end subroutine foxfilt
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