WSJT-X/lib/ft4/getcandidates4.f90

73 lines
1.7 KiB
Fortran

subroutine getcandidates4(id,fa,fb,syncmin,nfqso,maxcand,savg,candidate, &
ncand,sbase)
include 'ft4_params.f90'
real s(NH1,NHSYM)
real savg(NH1),savsm(NH1)
real sbase(NH1)
real x(NFFT1)
real window(NFFT1)
complex cx(0:NH1)
real candidate(3,maxcand)
integer*2 id(NMAX)
integer indx(NH1)
integer ipk(1)
equivalence (x,cx)
logical first
data first/.true./
save first,window
if(first) then
first=.false.
pi=4.0*atan(1.)
window=0.5*(1-cos(pi*(/(i,i=1,NFFT1)/)/(NFFT1/2.0)))
window=window**2
endif
! Compute symbol spectra, stepping by NSTEP steps.
savg=0.
tstep=NSTEP/12000.0
df=12000.0/NFFT1 !3.125 Hz
fac=1.0/300.0
do j=1,NHSYM
ia=(j-1)*NSTEP + 1
ib=ia+NFFT1-1
if(ib.gt.NMAX) exit
x=fac*id(ia:ib)*window
call four2a(x,NFFT1,1,-1,0) !r2c FFT
do i=1,NH1
s(i,j)=real(cx(i))**2 + aimag(cx(i))**2
enddo
savg=savg + s(1:NH1,j) !Average spectrum
enddo
savsm=0.
do i=8,NH1-7
savsm(i)=sum(savg(i-7:i+7))/15.
enddo
nfa=fa/df
nfb=fb/df
np=nfb-nfa+1
indx=0
call indexx(savsm(nfa:nfb),np,indx)
xn=savsm(nfa+indx(nint(0.3*np)))
savsm=savsm/xn
ncand=0
f_offset = -1.5*12000/512
do i=1,maxcand
ipk=maxloc(savsm(nfa:nfb))
ip=nfa-1+ipk(1)
xmax=savsm(ip)
savsm(max(1,ip-8):min(NH1,ip+8))=0.0
if(xmax.ge.syncmin) then
ncand=ncand+1
candidate(1,ncand)=ip*df+f_offset
candidate(2,ncand)=-99.9
candidate(3,ncand)=xmax
else
exit
endif
enddo
return
end subroutine getcandidates4