WSJT-X/lib/ana932.f90

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530 B
Fortran
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subroutine ana932(dat,npts0,cdat,npts)
real dat(npts0)
complex cdat(262145)
n=log(float(npts0))/log(2.0)
nfft1=2**(n+1)
nfft2=9*nfft1/32
df932=11025.0/nfft1
fac=2.0/nfft1
do i=1,npts0/2
cdat(i)=fac*cmplx(dat(2*i-1),dat(2*i))
enddo
cdat(npts0/2+1:nfft1/2)=0.
call four2a(cdat,nfft1,1,-1,0) !Forward r2c FFT
call four2a(cdat,nfft2,1,1,1) !Inverse c2c FFT
npts=npts0*9.0/32.0 !Downsampled data length
npts2=npts
return
end subroutine ana932