pro srchpacket,fn,packetnum,packetbyte
; Search file named fn for the start of packets
packetbyte=lonarr(100000L)
packetnum=0
close,1
openr,1,fn
bytes=0L
d=0B
while 0 eq 0 do begin
  while (d ne '0f'X) and (not eof(1)) do begin
    readu,1,d
    bytes=bytes+1
  endwhile
  if eof(1) then goto, done
  readu,1,d
  bytes=bytes+1
  if d eq '92'X or d eq 'b2'X then begin
    packetnum=packetnum+1
    packetbyte(packetnum-1)=bytes-1
  endif
endwhile
done: packetbyte=packetbyte(0:packetnum-1)
end