mirror of
https://github.com/saitohirga/WSJT-X.git
synced 2024-12-24 19:50:29 -05:00
2464009f46
git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@7661 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
30 lines
714 B
Fortran
30 lines
714 B
Fortran
subroutine wspr5_downsample(iwave,c)
|
|
|
|
! Input: i*2 data in iwave() at sample rate 12000 Hz
|
|
! Output: Complex data in c(), sampled at 400 Hz
|
|
|
|
include 'wsprlf_params.f90'
|
|
parameter (NMAX=300*12000,NFFT2=NMAX/30)
|
|
integer*2 iwave(NMAX)
|
|
complex c(0:NZ-1)
|
|
complex c1(0:NFFT2-1)
|
|
complex cx(0:NMAX/2)
|
|
real x(NMAX)
|
|
equivalence (x,cx)
|
|
|
|
df=12000.0/NMAX
|
|
x=iwave
|
|
call four2a(x,NMAX,1,-1,0) !r2c FFT to freq domain
|
|
i0=nint(1500.0/df)
|
|
c1(0)=cx(i0)
|
|
do i=1,NFFT2/2
|
|
c1(i)=cx(i0+i)
|
|
c1(NFFT2-i)=cx(i0-i)
|
|
enddo
|
|
c1=c1/NFFT2
|
|
call four2a(c1,NFFT2,1,1,1) !c2c FFT back to time domain
|
|
c=c1(0:NZ-1)
|
|
|
|
return
|
|
end subroutine wspr5_downsample
|