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30 lines
627 B
FortranFixed
30 lines
627 B
FortranFixed
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subroutine detect(data,npts,f,y)
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C Compute powers at the tone frequencies using 1-sample steps.
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parameter (NZ=11025,NSPD=25)
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real data(npts)
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real y(npts)
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complex c(NZ)
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complex csum
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data twopi/6.283185307/
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dpha=twopi*f/11025.0
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do i=1,npts
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c(i)=data(i)*cmplx(cos(dpha*i),-sin(dpha*i))
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enddo
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csum=0.
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do i=1,NSPD
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csum=csum+c(i)
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enddo
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y(1)=real(csum)**2 + imag(csum)**2
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do i=2,npts-(NSPD-1)
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csum=csum-c(i-1)+c(i+NSPD-1)
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y(i)=real(csum)**2 + imag(csum)**2
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enddo
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return
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end
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