diff --git a/lib/t1.f90 b/lib/t1.f90
index 5467e5a0c..e15337dfc 100644
--- a/lib/t1.f90
+++ b/lib/t1.f90
@@ -1,13 +1,32 @@
 program t1
 
   character*22 msg
+  character*12 arg
   complex c3(0:4096-1)
   complex c5(0:4096-1)
 
-  do i=1,999
+  call getarg(1,arg)
+  read(arg,*) nfile
+
+  do ifile=1,999
      read(51,end=999) nutc,nsnr,xdt,nfreq,msg,c3,c5
-     write(*,1010) nutc,nsnr,xdt,nfreq,msg
-1010 format(2i6,f7.1,i6,2x,a22)
+     write(*,1010) ifile,nutc,nsnr,xdt,nfreq,msg
+1010 format(3i6,f7.1,i6,2x,a22)
+
+     if(ifile.eq.nfile) then
+        c3=c5
+        c3(1353:)=0
+        call four2a(c3,2048,1,-1,1)
+
+        df=12000.0/(128.0*2048.0)
+        do i=0,2048
+           freq=i*df
+           if(i.ge.1024) freq=(i-2048)*df
+           s=1.e-4*(real(c3(i))**2 + aimag(c3(i))**2)
+           write(13,3001) i,freq,s
+3001       format(i6,2f10.3)
+        enddo
+     endif
   enddo
 
 999 end program t1