WSJT-X/libm65/qra64zap.f90

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Fortran
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subroutine qra64zap(cx,cy,xpol,nzap)
parameter (NFFT1=5376000) !56*96000
parameter (NFFT2=336000) !56*6000 (downsampled by 1/16)
complex cx(0:NFFT2-1),cy(0:NFFT2-1)
real s(-1312:1312)
integer iloc(1)
logical xpol
slimit=3.0
sbottom=1.5
nadd=128
nblks=NFFT2/nadd
nbh=nblks/2
k=-1
s=0.
df=nadd*96000.0/NFFT1
do i=1,nblks
j=i
if(j.gt.nblks/2) j=j-nblks
do n=1,nadd
k=k+1
s(j)=s(j) + real(cx(k))**2 + aimag(cx(k))**2
if(xpol) s(j)=s(j) + real(cy(k))**2 + aimag(cy(k))**2
enddo
enddo
call pctile(s,nblks,45,base)
s=s/base
do nzap=1,3
iloc=maxloc(s)
ipk=iloc(1)-1313
smax=s(ipk)
nw=3
do n=1,3
nw=2*nw
if(ipk-2*nw.lt.-1312) cycle
if(ipk+2*nw.gt. 1312) cycle
s1=maxval(s(ipk-2*nw:ipk-nw))
s2=maxval(s(ipk+nw:ipk+2*nw))
if(smax.gt.slimit .and. s1.lt.sbottom .and. s2.lt.sbottom) then
s(ipk-nw:ipk+nw)=1.0
i0=ipk
if(i0.lt.0) i0=i0+2625
ia=(i0-nw)*nadd
ib=(i0+nw)*nadd
cx(ia:ib)=0.
cy(ia:ib)=0.
exit
endif
enddo
enddo
! rewind 75
! do i=-nbh,nbh
! freq=i*df
! write(75,3001) freq,s(i)
!3001 format(2f12.3)
! enddo
! flush(75)
return
end subroutine qra64zap