WSJT-X/lib/blanker.f90

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subroutine blanker(iwave,nz,ndropmax,npct,c_bigfft)
integer*2 iwave(nz)
complex c_bigfft(0:nz/2)
integer hist(0:32768)
real fblank !Fraction of points to be blanked
fblank=0.01*npct
hist=0
do i=1,nz
! ### NB: if iwave(i)=-32768, abs(iwave(i))=-32768 ###
if(iwave(i).eq.-32768) iwave(i)=-32767
n=abs(iwave(i))
hist(n)=hist(n)+1
enddo
n=0
do i=32768,0,-1
n=n+hist(i)
if(n.ge.nint(nz*fblank/ndropmax)) exit
enddo
nthresh=i
ndrop=0
ndropped=0
xx=0.
do i=1,nz
i0=iwave(i)
if(ndrop.gt.0) then
i0=0
ndropped=ndropped+1
ndrop=ndrop-1
endif
! Start to apply blanking
if(abs(i0).gt.nthresh) then
i0=0
ndropped=ndropped+1
ndrop=ndropmax
endif
! Now copy the data into c_bigfft
if(iand(i,1).eq.1) then
xx=i0
else
yy=i0
j=i/2 - 1
c_bigfft(j)=cmplx(xx,yy)
endif
enddo
fblanked=fblanked + 0.1*(float(ndropped)/nz - fblanked)
fblanked=float(ndropped)/nz
! write(*,3001) npct,nthresh,fblanked
!3001 format(2i5,f7.3)
return
end subroutine blanker