WSJT-X/lib/downsam9.f90
Joe Taylor 3fdde76420 The "big FFTs" should be computed only once for each new set of Rx data.
This requires setting newdat=0 after the big FFT is computed.  In the OMP
code this must be done separately for each mode; so new variables newdat9 
and newdat65 have been defined.  Both are set to "newdat", the value
forwarded from the GUI, each time jt9[_omp][.exe] goes into action. 


git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@4946 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
2015-02-08 15:07:31 +00:00

88 lines
2.2 KiB
Fortran

subroutine downsam9(id2,npts8,nsps8,newdat,nspsd,fpk,c2,nz2)
!Downsample from id2() into c2() so as to yield nspsd samples per symbol,
!mixing from fpk down to zero frequency. The downsample factor is 432.
use, intrinsic :: iso_c_binding
use FFTW3
include 'constants.f90'
integer(C_SIZE_T) NMAX1
parameter (NMAX1=604800)
type(C_PTR) :: plan !Pointers plan for big FFT
integer*2 id2(0:8*npts8-1)
real*4, pointer :: x1(:)
complex c1(0:NMAX1/2)
complex c2(0:1440-1)
real s(5000)
logical first
common/patience/npatience,nthreads
data first/.true./
save plan,first,c1,s,x1
nfft1=NMAX1 !Forward FFT length
df1=12000.0/nfft1
npts=8*npts8
if(first) then
nflags=FFTW_ESTIMATE
if(npatience.eq.1) nflags=FFTW_ESTIMATE_PATIENT
if(npatience.eq.2) nflags=FFTW_MEASURE
if(npatience.eq.3) nflags=FFTW_PATIENT
if(npatience.eq.4) nflags=FFTW_EXHAUSTIVE
! Plan the FFTs just once
!$omp critical(fftw) ! serialize non thread-safe FFTW3 calls
plan=fftwf_alloc_real(NMAX1)
call c_f_pointer(plan,x1,[NMAX1])
x1(0:NMAX1-1) => x1 !remap bounds
call fftwf_plan_with_nthreads(nthreads)
plan=fftwf_plan_dft_r2c_1d(nfft1,x1,c1,nflags)
call fftwf_plan_with_nthreads(1)
!$omp end critical(fftw)
first=.false.
endif
if(newdat.eq.1) then
x1(0:npts-1)=id2(0:npts-1)
x1(npts:nfft1-1)=0. !Zero the rest of x1
call timer('FFTbig9 ',0)
call fftwf_execute_dft_r2c(plan,x1,c1)
call timer('FFTbig9 ',1)
nadd=int(1.0/df1)
s=0.
do i=1,5000
j=int((i-1)/df1)
do n=1,nadd
j=j+1
s(i)=s(i)+real(c1(j))**2 + aimag(c1(j))**2
enddo
enddo
newdat=0
endif
ndown=8*nsps8/nspsd !Downsample factor
nfft2=nfft1/ndown !Backward FFT length
nh2=nfft2/2
nf=nint(fpk)
i0=int(fpk/df1)
nw=100
ia=max(1,nf-nw)
ib=min(5000,nf+nw)
call pctile(s(ia),ib-ia+1,40,avenoise)
fac=sqrt(1.0/avenoise)
do i=0,nfft2-1
j=i0+i
if(i.gt.nh2) j=j-nfft2
c2(i)=fac*c1(j)
enddo
call four2a(c2,nfft2,1,1,1) !FFT back to time domain
nz2=8*npts8/ndown
return
end subroutine downsam9