83 lines
2.0 KiB
Plaintext
83 lines
2.0 KiB
Plaintext
subroutine getfc2w(c,csync,npeaks,fs,fc1,fpks)
|
|
|
|
include 'wsprlf_params.f90'
|
|
|
|
complex c(0:NZ-1) !Complex waveform
|
|
complex cs(0:NZ-1) !For computing spectrum
|
|
complex csync(0:NZ-1) !Sync symbols only, from cbb
|
|
real a(5)
|
|
real freqs(413),sp2(413),fpks(npeaks)
|
|
integer pkloc(1)
|
|
|
|
df=fs/NZ
|
|
baud=fs/NSPS
|
|
a(1)=-fc1
|
|
a(2:5)=0.
|
|
call twkfreq1(c,NZ,fs,a,cs) !Mix down by fc1
|
|
|
|
! Filter, square, then FFT to get refined carrier frequency fc2.
|
|
call four2a(cs,NZ,1,-1,1) !To freq domain
|
|
|
|
ia=nint(0.75*baud/df)
|
|
cs(ia:NZ-1-ia)=0. !Save only freqs around fc1
|
|
call four2a(cs,NZ,1,1,1) !Back to time domain
|
|
cs=cs/NZ
|
|
cs=cs*cs !Square the data
|
|
call four2a(cs,NZ,1,-1,1) !Compute squared spectrum
|
|
|
|
! Find two peaks separated by baud
|
|
pmax=0.
|
|
fc2=0.
|
|
ja=nint(0.3*baud/df)
|
|
k=1
|
|
do j=-ja,ja
|
|
f2=j*df
|
|
ia=nint((f2-0.5*baud)/df)
|
|
if(ia.lt.0) ia=ia+NZ
|
|
ib=nint((f2+0.5*baud)/df)
|
|
p=real(cs(ia))**2 + aimag(cs(ia))**2 + &
|
|
real(cs(ib))**2 + aimag(cs(ib))**2
|
|
if(p.gt.pmax) then
|
|
pmax=p
|
|
fc2=0.5*f2
|
|
endif
|
|
freqs(k)=0.5*f2
|
|
sp2(k)=p
|
|
k=k+1
|
|
! write(52,1200) f2,p,db(p)
|
|
!1200 format(f10.3,2f15.3)
|
|
enddo
|
|
|
|
do i=1,npeaks
|
|
pkloc=maxloc(sp2)
|
|
ipk=pkloc(1)
|
|
fpks(i)=freqs(ipk)
|
|
ipk0=max(1,ipk-1)
|
|
ipk1=min(413,ipk+1)
|
|
! ipk0=ipk
|
|
! ipk1=ipk
|
|
sp2(ipk0:ipk1)=0.0
|
|
!write(*,*) i,fpks(i),fc2
|
|
enddo
|
|
|
|
a(1)=-fc1
|
|
a(2:5)=0.
|
|
call twkfreq1(c,NZ,fs,a,cs) !Mix down by fc1
|
|
cs=cs*conjg(csync)
|
|
call four2a(cs,NZ,1,-1,1) !To freq domain
|
|
pmax=0.
|
|
do i=0,NZ-1
|
|
f=i*df
|
|
if(i.gt.NZ/2) f=(i-NZ)*df
|
|
p=real(cs(i))**2 + aimag(cs(i))**2
|
|
! write(51,3001) f,p,db(p)
|
|
!3001 format(f10.3,e12.3,f10.3)
|
|
if(p.gt.pmax) then
|
|
pmax=p
|
|
fc3=f
|
|
endif
|
|
enddo
|
|
|
|
return
|
|
end subroutine getfc2w
|