diff --git a/gcom2.f90 b/gcom2.f90
index c244154ce..862b7aad2 100644
--- a/gcom2.f90
+++ b/gcom2.f90
@@ -8,6 +8,7 @@ real ccf               !CCF in time (blue curve)                Decoder
 real green             !Data for green line                     GUI
 real fselect           !Specified QSO frequency                 GUI
 real pctlost           !Percent of lost packets                 Decoder
+real pctblank          !Percent of blanked blocks/packets       Decoder
 real rxnoise           !Rx noise in dB                        recvpkt
 real dphi              !Phase shift between pol'n channels   GUI,Decoder
 integer ngreen         !Length of green                         GUI
@@ -103,7 +104,7 @@ 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),           &
-     green(500),fselect,pctlost,rxnoise,dphi,ngreen,dgain,iter,             &
+     green(500),fselect,pctlost,pctblank,rxnoise,dphi,ngreen,dgain,iter,    &
      ndecoding,ndecoding0,mousebutton,multicast,                            &
      ndecdone,npingtime,ierr,lauto,mantx,nrestart,ntr,nmsg,nsave,nadd5,     &
      dftolerance,LDecoded,rxdone,monitoring,nzap,minsigdb,                  &
diff --git a/map65.py b/map65.py
index 7b5bdb029..c6f2f2eac 100644
--- a/map65.py
+++ b/map65.py
@@ -970,13 +970,10 @@ def update():
         t=time.strftime('%Y %b %d\n%H:%M:%S',utc)
         Audio.gcom2.utcdate=t[:12]
         ldate.configure(text=t)
-        t="Rx noise: %.1f dB" % Audio.gcom2.rxnoise
+        t="Rx: %.1f dB  %.1f %%" % (Audio.gcom2.rxnoise,Audio.gcom2.pctblank)
         msg4.configure(text=t)
         t="Drop: %.2f %%" % Audio.gcom2.pctlost
         msg5.configure(text=t)
-##        t="%d  %.2f  %.2f" % (Audio.datcom.kbuf,Audio.datcom.kk/(60.0*96000.0), \
-##                            Audio.datcom.kxp/(60.0*96000.0))
-        msg5.configure(text=t)
         root_geom=root.geometry()
         try:
             bm_geom=bm.geometry()
@@ -1620,12 +1617,14 @@ f5a.pack(side=LEFT,expand=1,fill=BOTH)
 #------------------------------------------------------ Receiving parameters
 f5b=Frame(iframe5,bd=2,relief=GROOVE)
 nzap=IntVar()
+bblank=Checkbutton(f5b,text='NB',justify=RIGHT,variable=nblank)
+bblank.grid(column=0,row=0,padx=2,pady=20,sticky='EW')
 ltol=Label(f5b, bg='white', fg='black', text='Tol    400', width=8, relief=RIDGE)
-ltol.grid(column=0,row=2,padx=2,pady=1,sticky='EW')
+ltol.grid(column=0,row=1,padx=2,pady=1,sticky='EW')
 Widget.bind(ltol,'<Button-1>',inctol)
 Widget.bind(ltol,'<Button-3>',dectol)
 ldsec=Label(f5b, bg='white', fg='black', text='Dsec  0.0', width=8, relief=RIDGE)
-ldsec.grid(column=0,row=4,ipadx=3,padx=2,pady=5,sticky='EW')
+ldsec.grid(column=0,row=2,ipadx=3,padx=2,pady=5,sticky='EW')
 Widget.bind(ldsec,'<Button-1>',incdsec)
 Widget.bind(ldsec,'<Button-3>',decdsec)
 
diff --git a/recvpkt.F90 b/recvpkt.F90
index 3dfeec38c..a5826ed20 100644
--- a/recvpkt.F90
+++ b/recvpkt.F90
@@ -15,7 +15,7 @@ subroutine recvpkt(iarg)
   include 'gcom2.f90'
   equivalence (id,d8)
   data nblock0/0/,kb/1/,ns00/99/
-  data sqave/0.0/,u/0.001/,rxnoise/0.0/,kbuf/1/,lost_tot/0/
+  data sqave/0.0/,u/0.001/,rxnoise/0.0/,pctblank/0.0/,kbuf/1/,lost_tot/0/
   data multicast0/-99/
   save
 
diff --git a/symspec.f90 b/symspec.f90
index f24e61cf8..e5b0f8ba0 100644
--- a/symspec.f90
+++ b/symspec.f90
@@ -30,8 +30,65 @@ subroutine symspec(id,kbuf,kk,kkdone,nutc,newdat)
            szavg(ip,i)=0.
         enddo
      enddo
+
+! Get baseline power level for this minute
+     n1=174                               !Block size (somewhat arbitrary)
+     n2=(kkk-kkdone)/n1                    !Number of blocks
+     k=0                                  !Starting place
+     sqq=0.
+     nsqq=0
+     do j=1,n2
+        sq=0.
+        do i=1,n1                         !Find power in each block
+           k=k+1
+           x1=id(1,k,kbuf)
+           x2=id(2,k,kbuf)
+           x3=id(3,k,kbuf)
+           x4=id(4,k,kbuf)
+           sq=sq + x1*x1 + x2*x2 + x3*x3 + x4*x4
+        enddo
+        if(sq.lt.n1*10000.) then          !Find power in good blocks
+           sqq=sqq+sq
+           nsqq=nsqq+1
+        endif
+     enddo
+     sqave=sqq/nsqq                       !Average power in good blocks
+     nclip=0
+     nz2=0
   endif
 
+  if(nblank.ne.0) then
+! Apply final noise blanking
+     n2=(kkk-kkdone)/n1
+     k=kkdone
+     do j=1,n2
+        sq=0.
+        do i=1,n1
+           k=k+1
+           x1=id(1,k,kbuf)
+           x2=id(2,k,kbuf)
+           x3=id(3,k,kbuf)
+           x4=id(4,k,kbuf)
+           sq=sq + x1*x1 + x2*x2 + x3*x3 + x4*x4
+        enddo
+! If power in this block is excessive, blank it.
+        if(sq.gt.1.5*sqave) then
+           do i=k-n1+1,k
+              id(1,i,kbuf)=0
+              id(2,i,kbuf)=0
+              id(3,i,kbuf)=0
+              id(4,i,kbuf)=0
+           enddo
+           nclip=nclip+1
+        endif
+     enddo
+     nz2=nz2+n2
+     pctblank=nclip*100.0/nz2
+!     write(*,3002) nblank,n2,nz2,nclip,kkk,kkdone,pctblank,sqave
+!3002 format(4i6,2i9,f8.1,f10.0)
+  endif
+!###
+
   do nn=1,ntot
      i0=ts+hsym                           !Starting sample pointer
      if((i0+npts-1).gt.kkk) go to 998     !See if we have enough points