WSJT-X/lib/lpf1.f90
2020-02-21 13:36:49 -05:00

30 lines
609 B
Fortran

subroutine lpf1(dd,jz,dat,jz2)
parameter (NFFT1=64*11025,NFFT2=32*11025)
real dd(jz)
real dat(jz)
real x(NFFT1)
complex cx(0:NFFT1/2)
equivalence (x,cx)
save x,cx
fac=1.0/float(NFFT1)
x(1:jz)=fac*dd(1:jz)
x(jz+1:NFFT1)=0.0
call four2a(cx,NFFT1,1,-1,0) !Forwarxd FFT, r2c
cx(NFFT2/2:)=0.0
! df=11025.0/NFFT1
! do i=1,NFFT1/2
! sx=real(cx(i))**2 + aimag(cx(i))**2
! write(50,3000) i*df,sx
!3000 format(f15.6,e12.3)
! enddo
call four2a(cx,NFFT2,1,1,-1) !Inverse FFT, c2r
jz2=jz/2
dat(1:jz2)=x(1:jz2)
return
end subroutine lpf1