diff --git a/gcom2.f90 b/gcom2.f90
index 2cf692a58..a8f0fedc3 100644
--- a/gcom2.f90
+++ b/gcom2.f90
@@ -1,6 +1,7 @@
 ! Variable             Purpose                              Set in Thread
 !-------------------------------------------------------------------------
 real*8 fcenter         !Linrad center freq, from pkt header   recvpkt
+real*8 forcefcenter    !Optional override of fcenter            GUI
 real ps0               !Spectrum of best ping, FSK441/JT6m      Decoder
 real psavg             !Average spectrum                        Decoder
 real s2                !2d spectrum for horizontal waterfall    GUI
@@ -105,7 +106,7 @@ character*80 filetokillb
 character*12 pttport
 character*8 utcdata     !HHMM UTC for the processed data       Decoder
 
-common/gcom2/fcenter,ps0(431),psavg(450),s2(64,3100),ccf(-5:540),           &
+common/gcom2/fcenter,forcefcenter,ps0(431),psavg(450),s2(64,3100),ccf(-5:540), &
      green(500),fselect,pctlost,pctblank,rxnoise,dphi,ngreen,dgain,         &
      ndecoding,ndecoding0,mcall3,mousebutton,multicast,nsetftx,ierr,        &
      ndecdone,nfloat,lauto,mantx,nrestart,ntr,nmsg,nsave,nadd5,             &
diff --git a/map65.py b/map65.py
index ce3a6df4f..8f8402729 100644
--- a/map65.py
+++ b/map65.py
@@ -1344,6 +1344,10 @@ def update():
         Audio.gcom2.nt1=options.nt1.get()
     except:
         Audio.gcom2.nt1=48
+    try:
+        Audio.gcom2.forcefcenter=options.forceFcenter.get()
+    except:
+        Audio.gcom2.forcefcenter=0.0
     t=options.savedir.get() + \
         '                                        ' + \
         '                                        '
@@ -1862,6 +1866,7 @@ try:
         elif key == 'fcal': options.fcal.set(value)
         elif key == 'CSmin': options.ncsmin.set(value)
         elif key == 'Nt1': options.nt1.set(value)
+        elif key == 'ForceFcenter': options.forceFcenter.set(value)
         elif key == 'dphi': options.dphi.set(value)
         elif key == 'SaveDir': options.savedir.set(value.replace("#"," "))
         elif key == 'AzElDir': options.azeldir.set(value.replace("#"," "))
@@ -1960,6 +1965,7 @@ f.write("fb " + str(options.fb.get()) + "\n")
 f.write("fcal " + str(options.fcal.get()) + "\n")
 f.write("CSmin " + str(options.ncsmin.get()) + "\n")
 f.write("Nt1 " + str(options.nt1.get()) + "\n")
+f.write("ForceFcenter " + str(options.forceFcenter.get()) + "\n")
 savedir2=options.savedir.get().replace(" ","#")
 azeldir2=options.azeldir.get().replace(" ","#")
 f.write("SaveDir " + str(savedir2) + "\n")
diff --git a/options.py b/options.py
index 46cd41ba1..e0bc9d01d 100644
--- a/options.py
+++ b/options.py
@@ -30,6 +30,7 @@ ndevin=IntVar()
 ndevout=IntVar()
 DevinName=StringVar()
 DevoutName=StringVar()
+forceFcenter=DoubleVar()
 samfacin=DoubleVar()
 samfacout=DoubleVar()
 Template1=StringVar()
@@ -117,13 +118,15 @@ min_callsign_entry=Pmw.EntryField(g3.interior(),labelpos=W, \
     label_text='CSmin:',entry_width=9,value=4,entry_textvariable=ncsmin)
 nt1_entry=Pmw.EntryField(g3.interior(),labelpos=W, \
     label_text='Rx t1:',entry_width=9,value=48,entry_textvariable=nt1)
+forceFreq_entry=Pmw.EntryField(g3.interior(),labelpos=W, \
+    label_text='Force Fcenter:',entry_width=9,value=0,entry_textvariable=forceFcenter)
 savedir_entry=Pmw.EntryField(g3.interior(),labelpos=W,label_text='SaveDir:',
     entry_width=23,value=g.appdir+'\save',entry_textvariable=savedir)
 azeldir_entry=Pmw.EntryField(g3.interior(),labelpos=W,label_text='AzElDir:',
     entry_width=23,value=g.appdir,entry_textvariable=azeldir)
 widgets = (temp_prefix,aux_ra,aux_dec,nkeep_entry,dphi_entry, \
            fa_entry,fb_entry,fcal_entry,min_callsign_entry, \
-           nt1_entry,savedir_entry,azeldir_entry,)
+           nt1_entry,forceFreq_entry,savedir_entry,azeldir_entry,)
 for widget in widgets:
     widget.pack(padx=2,pady=2)
 Pmw.alignlabels(widgets)
diff --git a/recvpkt.F90 b/recvpkt.F90
index dcc337e00..77a76f734 100644
--- a/recvpkt.F90
+++ b/recvpkt.F90
@@ -47,6 +47,7 @@ subroutine recvpkt(iarg)
   nsec=mod(Tsec,86400.d0)           !Time according to MAP65
   nseclr=msec/1000                  !Time according to Linrad
   fcenter=center_freq
+  if(forcefcenter.gt.0.0) fcenter=forcefcenter
 
 ! Reset buffer pointers at start of minute.
   ns=mod(nsec,60)
@@ -145,6 +146,7 @@ subroutine recvpkt(iarg)
         if(ns.ge.nt1 .and. ndone1.eq.0 .and. synced) then
            nutc=mutc
            fcenter=center_freq
+           if(forcefcenter.gt.0.0) fcenter=forcefcenter
            kbuf=kb
            kk=k
            ndiskdat=0