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https://github.com/saitohirga/WSJT-X.git
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76 lines
1.5 KiB
Fortran
76 lines
1.5 KiB
Fortran
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program t3
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parameter (NBLK=3456,NZ=10*NBLK)
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real x0(NZ)
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real x1(NZ)
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twopi=8.0*atan(1.0)
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dphi=twopi*1000.0/12000.0
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phi=0.
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do i=1,NZ
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phi=phi+dphi
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x0(i)=sin(phi)
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if(mod(i,10007).eq.100) x0(i)=2.0
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enddo
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do j=1,10
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ib=j*NBLK
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ia=ib-NBLK+1
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call filter(x0(ia:ib),x1(ia:ib))
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enddo
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do i=1,NZ
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write(13,1001) i,x0(i),x1(i),x1(i)-x0(i)
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1001 format(i6,3e12.3)
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enddo
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end program t3
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subroutine filter(x0,x1)
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! Process time-domain data sequentially, optionally using 'refspec.dat'
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! to flatten the spectrum.
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! NB: sin^2 window with 50% overlap; sin^2 + cos^2 = 1.0.
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parameter (NFFT=6912,NH=NFFT/2)
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real x0(0:NH-1) !Real input data
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real x1(0:NH-1) !Real output data
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real xov(0:NH-1)
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real x(0:NFFT-1)
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complex cx(0:NH)
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real*4 w(0:NFFT-1)
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real*4 s(0:NH)
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logical first
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equivalence (x,cx)
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data first/.true./
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save
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if(first) then
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pi=4.0*atan(1.0)
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do i=0,NFFT-1
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w(i)=(sin(i*pi/NFFT))**2
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enddo
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s=0.
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fac=1.0/NFFT
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first=.false.
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xov=0.
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endif
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x(:NH-1)=xov !Previous 2nd half to new 1st half
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x(NH:)=x0 !New 2nd half
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x=x*w !Apply window
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call four2a(x,NFFT,1,-1,0) !r2c FFT: to freq domain
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! Apply filter to cx()
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call four2a(cx,NFFT,1,1,-1) !c2r FFT: back to time domain
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x(0:NH-1)=x(0:NH-1)+xov(0:NH-1) !Add previous segment's 2nd half
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x1=x
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return
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end subroutine filter
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