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53 lines
1.0 KiB
Fortran
53 lines
1.0 KiB
Fortran
subroutine filt8(f0,nslots,width,wave)
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parameter (NFFT=180000,NH=NFFT/2)
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real wave(NFFT)
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real x(NFFT)
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real s1(0:NH)
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real s2(0:NH)
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complex cx(0:NH)
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equivalence (x,cx)
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x=wave
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call four2a(cx,NFFT,1,-1,0) !r2c
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df=12000.0/NFFT
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fa=f0 - 0.5*6.25
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fb=f0 + 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/nfft
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!###
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if(nslots.ne.99) return
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x=wave
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call four2a(cx,NFFT,1,-1,0) !r2c
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do i=0,NH
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s1(i)=real(cx(i))**2 + aimag(cx(i))**2
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enddo
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nadd=20
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call smo(s1,NH+1,s2,nadd)
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do i=0,NH
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freq=i*df
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write(29,3101) freq,db(s2(i)) - 72.0
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3101 format(2f12.3)
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enddo
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!###
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return
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end subroutine filt8
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