diff --git a/lib/fsk4hf/sync8.f90 b/lib/fsk4hf/sync8.f90
new file mode 100644
index 000000000..019f830a3
--- /dev/null
+++ b/lib/fsk4hf/sync8.f90
@@ -0,0 +1,76 @@
+subroutine sync8(iwave,xdt,f1,s)
+
+  include 'ft8_params.f90'
+  parameter (IZ=10,JZ=20)
+  character*1 line(-JZ:JZ),mark(0:6)
+  complex cx(0:NH1)
+  real s(NH1,NHSYM)
+  real savg(NH1)
+  real x(NFFT1)
+  real sync2d(-IZ:IZ,-JZ:JZ)
+  integer*2 iwave(NMAX)
+  integer iloc(1)
+  integer icos7(0:6)
+  data icos7/2,5,6,0,4,1,3/                   !Costas 7x7 tone pattern
+  data mark/' ',' ','.','-','+','X','$'/
+  equivalence (x,cx)
+
+! Compute symbol spectra at half-symbol steps.  
+  savg=0.
+  istep=NSPS/2
+  tstep=istep/12000.0
+  df=12000.0/NFFT1
+
+  fac=1.0/300.0
+  do j=1,NHSYM
+     ia=(j-1)*istep + 1
+     ib=ia+NSPS-1
+     x(1:NSPS)=fac*iwave(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)
+  enddo
+
+  ia=nint(30.0/df)
+  ib=nint(3000.0/df)
+  savg=savg/NHSYM
+  pmax=0.
+  i0=0
+  do i=ia,ib
+     p=sum(savg(i-8:i+8))/17.0
+     if(p.gt.pmax) then
+        pmax=p
+        i0=i-7
+     endif
+  enddo
+
+  tmax=0.
+  ipk=0
+  jpk=0
+  j0=1 + nint(0.5/tstep)
+  do i=-IZ,IZ
+     do j=-JZ,JZ
+        t=0.
+        do n=0,6
+           k=j0+j+2*n
+           if(k.ge.1) t=t + s(i0+i+2*icos7(n),k)
+           t=t + s(i0+i+2*icos7(n),k+72)
+           if(k+144.le.NHSYM) t=t + s(i0+i+2*icos7(n),k+144)
+        enddo
+        sync2d(i,j)=t
+        if(t.gt.tmax) then
+           tmax=t
+           jpk=j
+           ipk=i
+        endif
+     enddo
+  enddo
+  f0=i0*df
+  f1=(i0+ipk)*df
+  xdt=jpk*tstep
+
+  return
+end subroutine sync8