WSJT-X/lib/fsk4hf/getcandidates4.f90

64 lines
1.5 KiB
Fortran

subroutine getcandidates4(id,fa,fb,syncmin,nfqso,maxcand,savg,candidate, &
ncand,sbase)
! For now, hardwired to find the largest peak in the average spectrum
include 'ft2_params.f90'
real s(NH1,NHSYM)
real savg(NH1),savsm(NH1)
real sbase(NH1)
real x(NFFT1)
complex cx(0:NH1)
real candidate(3,maxcand)
integer*2 id(NMAX)
integer*1 s8(8)
integer indx(NH1)
data s8/0,1,1,1,0,0,1,0/
equivalence (x,cx)
! 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+NSPS-1
x(1:NSPS)=fac*id(ia:ib)
x(NSPS+1:)=0.
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=2,NH1-1
savsm(i)=sum(savg(i-1:i+1))/3.
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
imax=-1
xmax=-99.
do i=2,NH1-1
if(savsm(i).gt.savsm(i-1).and. &
savsm(i).gt.savsm(i+1).and. &
savsm(i).gt.xmax) then
xmax=savsm(i)
imax=i
endif
enddo
f0=imax*df
if(xmax.gt.1.2) then
ncand=ncand+1
candidate(1,ncand)=f0
endif
return
end subroutine getcandidates4