merge ordm/receiver branch -r5574:5659. Reworks OFDM receiver with refactored OFDM blocks. A few bug fixes for other blocks have also been slipped in.

git-svn-id: http://gnuradio.org/svn/gnuradio/trunk@5661 221aa14e-8319-0410-a670-987f0aec2ac5

8 files changed, 290 insertions, 427 deletions

diff --git a/gnuradio-examples/python/ofdm/Makefile.am b/gnuradio-examples/python/ofdm/Makefile.am
index 23df3f9d6..cbaa45b5c 100644
--- a/gnuradio-examples/python/ofdm/Makefile.am
+++ b/gnuradio-examples/python/ofdm/Makefile.am
@@ -25,8 +25,6 @@ EXTRA_DIST = 					\
 		benchmark_ofdm_tx.py		\
 		fftshift.py			\
 		fusb_options.py			\
-		ofdm.py				\
-		ofdm_receiver.py		\
 		pick_bitrate.py			\
 		receive_path.py			\
 		transmit_path.py
diff --git a/gnuradio-examples/python/ofdm/benchmark_ofdm.py b/gnuradio-examples/python/ofdm/benchmark_ofdm.py
index 3b4761d5e..53f4bd0bf 100755
--- a/gnuradio-examples/python/ofdm/benchmark_ofdm.py
+++ b/gnuradio-examples/python/ofdm/benchmark_ofdm.py
@@ -1,6 +1,6 @@
 #!/usr/bin/env python
 #
-# Copyright 2005, 2006 Free Software Foundation, Inc.
+# Copyright 2006, 2007 Free Software Foundation, Inc.
 # 
 # This file is part of GNU Radio
 # 
@@ -20,90 +20,68 @@
 # Boston, MA 02110-1301, USA.
 # 
 
-from gnuradio import gr, gru, modulation_utils
-from gnuradio import usrp
+from gnuradio import gr, blks
 from gnuradio import eng_notation
 from gnuradio.eng_option import eng_option
 from optparse import OptionParser
+from gnuradio.blksimpl import ofdm_pkt
 
 import random, time, struct, sys, math, os
 
 # from current dir
 from transmit_path import transmit_path
 from receive_path import receive_path
-import ofdm
 
-class awgn_channel(gr.hier_block):
-    def __init__(self, fg, sample_rate, noise_voltage, frequency_offset):
-
-        self.input = gr.add_const_cc(0)
-
-        self.noise_adder = gr.add_cc()
-        self.noise = gr.noise_source_c(gr.GR_GAUSSIAN,noise_voltage)
-        self.offset = gr.sig_source_c(1, gr.GR_SIN_WAVE, frequency_offset, 1.0, 0.0)
-        self.mixer_offset = gr.multiply_cc()
-
-        fg.connect(self.input, (self.mixer_offset,0))
-        fg.connect(self.offset,(self.mixer_offset,1))
-        fg.connect(self.mixer_offset, (self.noise_adder,1))
-        fg.connect(self.noise, (self.noise_adder,0))
-
-        gr.hier_block.__init__(self, fg, self.input, self.noise_adder)
-
-class multipath_channel(gr.hier_block):
-    def __init__(self, fg):
-
-        self.taps = [1.0, .2, 0.0, .1, .08, -.4, .12, -.2, 0, 0, 0, .3]
-        self.chan = gr.fir_filter_ccc(1, self.taps)
-        
-        gr.hier_block.__init__(self, fg, self.chan, self.chan)
 
 class my_graph(gr.flow_graph):
     def __init__(self, callback, options):
         gr.flow_graph.__init__(self)
 
-        channel_on = True
-
-        SNR = 10.0**(options.snr/10.0)
-        frequency_offset = options.frequency_offset / options.fft_length
-        
-        power_in_signal = options.occupied_tones
-        noise_power_in_channel = power_in_signal/SNR
-        noise_power_required = noise_power_in_channel * options.fft_length / options.occupied_tones
-        noise_voltage = math.sqrt(noise_power_required)
-
-        self.txpath = transmit_path(self, options)
-        self.throttle = gr.throttle(gr.sizeof_gr_complex, options.sample_rate)
-        self.rxpath = receive_path(self, callback, options)
-
-        if channel_on:
-            self.channel = awgn_channel(self, options.sample_rate, noise_voltage, frequency_offset)
-            self.multipath = multipath_channel(self)
+        if options.channel_on:
+            SNR = 10.0**(options.snr/10.0)
+            power_in_signal = 1.0
+            noise_power_in_channel = power_in_signal/SNR
+            noise_voltage = math.sqrt(noise_power_in_channel/2.0)
+            print "Noise voltage: ", noise_voltage
 
-            if options.discontinuous:
-                z = 20000*[0,]
-                self.zeros = gr.vector_source_c(z, True)
-                packet_size = 15*((4+8+4+1500+4) * 8)
-                self.mux = gr.stream_mux(gr.sizeof_gr_complex, [packet_size-0, int(10e5)])
-
-                # Connect components
-                self.connect(self.txpath, (self.mux,0))
-                self.connect(self.zeros, (self.mux,1))
-                self.connect(self.mux, self.throttle, self.channel, self.rxpath)
-                self.connect(self.mux, gr.file_sink(gr.sizeof_gr_complex, "tx_ofdm.dat"))
+            frequency_offset = options.frequency_offset / options.fft_length
 
+            if options.multipath_on:
+                taps = [1.0, .2, 0.0, .1, .08, -.4, .12, -.2, 0, 0, 0, .3]
             else:
-                #self.connect(self.txpath, self.throttle, self.multipath, self.channel)
-                self.connect(self.txpath, self.throttle, self.channel)
-                self.connect(self.channel, self.rxpath)
-                self.connect(self.txpath, gr.file_sink(gr.sizeof_gr_complex, "tx_ofdm.dat"))
-            
+                taps = [1.0, 0.0]
+
+        else:
+            noise_voltage = 0.0
+            frequency_offset = 0.0
+            taps = [1.0, 0.0]
+
+        symbols_per_packet = math.ceil(((4+options.size+4) * 8) / options.occupied_tones)
+        samples_per_packet = (symbols_per_packet+2) * (options.fft_length+options.cp_length)
+        print "Symbols per Packet: ", symbols_per_packet
+        print "Samples per Packet: ", samples_per_packet
+        if options.discontinuous:
+            stream_size = [100000, int(options.discontinuous*samples_per_packet)]
         else:
-            self.connect(self.txpath, self.throttle, self.rxpath)
-            self.connect(self.txpath, gr.file_sink(gr.sizeof_gr_complex, "tx"))
-            self.connect(self.rxpath.ofdm_demod.ofdm_rx, gr.file_sink(options.fft_length*gr.sizeof_gr_complex, "rx"))
+            stream_size = [0, 100000]
 
+        z = [0,]
+        self.zeros = gr.vector_source_c(z, True)
+        self.txpath = transmit_path(self, options)
 
+        self.mux = gr.stream_mux(gr.sizeof_gr_complex, stream_size)
+        self.throttle = gr.throttle(gr.sizeof_gr_complex, options.sample_rate)
+        self.channel = blks.channel_model(self, noise_voltage, frequency_offset, options.clockrate_ratio, taps)
+        self.rxpath = receive_path(self, callback, options)
+                
+        self.connect(self.zeros, (self.mux,0))
+        self.connect(self.txpath, (self.mux,1))
+        self.connect(self.mux, self.throttle, self.channel, self.rxpath)
+        
+        self.connect(self.txpath, gr.file_sink(gr.sizeof_gr_complex, "txpath.dat"))
+        self.connect(self.mux, gr.file_sink(gr.sizeof_gr_complex, "mux.dat"))
+        self.connect(self.channel, gr.file_sink(gr.sizeof_gr_complex, "channel.dat"))
+            
 # /////////////////////////////////////////////////////////////////////////////
 #                                   main
 # /////////////////////////////////////////////////////////////////////////////
@@ -124,6 +102,17 @@ def main():
         if ok:
             n_right += 1
         print "ok: %r \t pktno: %d \t n_rcvd: %d \t n_right: %d" % (ok, pktno, n_rcvd, n_right)
+
+        printlst = list()
+        for x in payload[2:]:
+            t = hex(ord(x)).replace('0x', '')
+            if(len(t) == 1):
+                t = '0' + t
+            printlst.append(t)
+        printable = ''.join(printlst)
+
+        print printable
+        print "\n"
                 
     parser = OptionParser(option_class=eng_option, conflict_handler="resolve")
     expert_grp = parser.add_option_group("Expert")
@@ -137,21 +126,22 @@ def main():
                       help="set the SNR of the channel in dB [default=%default]")
     parser.add_option("", "--frequency-offset", type="eng_float", default=0,
                       help="set frequency offset introduced by channel [default=%default]")
-    parser.add_option("","--discontinuous", action="store_true", default=False,
-                      help="enable discontinous transmission (bursts of 5 packets)")
+    parser.add_option("", "--clockrate-ratio", type="eng_float", default=1.0,
+                      help="set clock rate ratio (sample rate difference) between two systems [default=%default]")
+    parser.add_option("","--discontinuous", type="int", default=0,
+                      help="enable discontinous transmission, burst of N packets [Default is continuous]")
+    parser.add_option("","--channel-on", action="store_true", default=True,
+                      help="Enables AWGN, freq offset")
+    parser.add_option("","--multipath-on", action="store_true", default=False,
+                      help="enable multipath")
 
     transmit_path.add_options(parser, expert_grp)
     receive_path.add_options(parser, expert_grp)
-    ofdm.ofdm_mod.add_options(parser, expert_grp)
-    ofdm.ofdm_demod.add_options(parser, expert_grp)
+    ofdm_pkt.mod_ofdm_pkts.add_options(parser, expert_grp)
+    ofdm_pkt.demod_ofdm_pkts.add_options(parser, expert_grp)
     
     (options, args) = parser.parse_args ()
-
-    if(options.mtu < options.size):
-        sys.stderr.write("MTU (%.0f) must be larger than the packet size (%.0f)\n"
-                         % (options.mtu, options.size))
-        sys.exit(1)
-        
+       
     # build the graph
     fg = my_graph(rx_callback, options)
     
@@ -167,12 +157,12 @@ def main():
     pktno = 0
     pkt_size = int(options.size)
 
-    
-    
     while n < nbytes:
-        r = ''.join([chr(random.randint(0,255)) for i in range(pkt_size-2)])
-        #pkt_contents = struct.pack('!H', pktno) + (pkt_size - 2) * chr(pktno & 0xff)
-        pkt_contents = struct.pack('!H', pktno) + r
+        #r = ''.join([chr(random.randint(0,255)) for i in range(pkt_size-2)])
+        #pkt_contents = struct.pack('!H', pktno) + r
+
+        pkt_contents = struct.pack('!H', pktno) + (pkt_size - 2) * chr(pktno & 0xff)
+
         send_pkt(pkt_contents)
         n += pkt_size
         #sys.stderr.write('.')
diff --git a/gnuradio-examples/python/ofdm/ofdm.py b/gnuradio-examples/python/ofdm/ofdm.py
deleted file mode 100644
index 8b1e616f9..000000000
--- a/gnuradio-examples/python/ofdm/ofdm.py
+++ /dev/null
@@ -1,161 +0,0 @@
-#!/usr/bin/env python
-#
-# Copyright 2004,2005,2006 Free Software Foundation, Inc.
-# 
-# This file is part of GNU Radio
-# 
-# GNU Radio is free software; you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation; either version 2, or (at your option)
-# any later version.
-# 
-# GNU Radio is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-# 
-# You should have received a copy of the GNU General Public License
-# along with GNU Radio; see the file COPYING.  If not, write to
-# the Free Software Foundation, Inc., 51 Franklin Street,
-# Boston, MA 02110-1301, USA.
-# 
-
-from gnuradio import gr
-from optparse import OptionParser
-from ofdm_receiver import ofdm_receiver
-
-class ofdm_mod(gr.hier_block):
-    def __init__(self, fg, options):
-        self.fg = fg
-        self._occupied_tones = options.occupied_tones
-        self._fft_length = options.fft_length
-        self._cp_length = options.cp_length
-        self._mtu = options.mtu
-
-        symbol_length = self._fft_length + self._cp_length
-
-        if self._fft_length < self._occupied_tones:
-            sys.stderr.write("occupied tones must be less than FFT length\n")
-            raise SystemExit
-        if self._fft_length < self._cp_length:
-            sys.stderr.write("cyclic prefix length  must be less than FFT length\n")
-            raise SystemExit
-
-        win = [] #[1 for i in range(self._fft_length)]
-
-        # hard-coded known symbol
-        #ks = self._occupied_tones*[1,]
-        ks1 = known_symbols_200_1
-        ks2 = known_symbols_200_2
-        
-        self.ofdm = gr.ofdm_bpsk_mapper(self._mtu, self._occupied_tones, self._fft_length, ks1, ks2)
-        self.ifft = gr.fft_vcc(self._fft_length, False, win, True)
-        self.cp_adder = gr.ofdm_cyclic_prefixer(self._fft_length, symbol_length)
-        
-        if options.verbose:
-            self._print_verbage()
-
-        self.fg.connect(self.ofdm, self.ifft, self.cp_adder)
-        gr.hier_block.__init__(self, self.fg, self.ofdm, self.cp_adder)
-
-    def samples_per_symbol(self):
-        return 2
-
-    def mtu(self):
-        return self._mtu
-
-    def bits_per_symbol(self=None):   # staticmethod that's also callable on an instance
-        return 1
-    bits_per_symbol = staticmethod(bits_per_symbol)      # make it a static method.  RTFM
-
-    def add_options(normal, expert):
-        """
-        Adds OFDM-specific options to the Options Parser
-        """
-        expert.add_option("", "--mtu", type="int", default=1500,
-                          help="set maximum transmit unit [default=%default]")
-        expert.add_option("", "--fft-length", type="intx", default=512,
-                          help="set the number of FFT bins [default=%default]")
-        expert.add_option("", "--occupied-tones", type="intx", default=200,
-                          help="set the number of occupied FFT bins [default=%default]")
-        expert.add_option("", "--cp-length", type="intx", default=128,
-                          help="set the number of bits in the cyclic prefix [default=%default]")
-    # Make a static method to call before instantiation
-    add_options = staticmethod(add_options)
-
-    def _print_verbage(self):
-        """
-        Prints information about the OFDM modulator
-        """
-        print "\nOFDM Modulator:"
-        print "FFT length:      %3d"   % (self._fft_length)
-        print "Occupied Tones:  %3d"   % (self._occupied_tones)
-        print "CP length:       %3d"   % (self._cp_length)
-
-
-class ofdm_demod(gr.hier_block):
-    def __init__(self, fg, options):
-        self.fg = fg
-        self._occupied_tones = options.occupied_tones
-        self._fft_length = options.fft_length
-        self._cp_length = options.cp_length
-        self._snr = options.snr
-
-        symbol_length = self._fft_length + self._cp_length
-
-        win = [1 for i in range(self._fft_length)]
-
-        # hard-coded known symbol
-        ks1 = known_symbols_200_1
-        ks2 = known_symbols_200_2
-
-        # ML Sync
-        self.ofdm_sync = ofdm_receiver(self.fg, self._fft_length, symbol_length, self._snr)
-
-        # OFDM Demod
-        self.fft_demod = gr.fft_vcc(self._fft_length, True, win, True)
-        self.ofdm_corr  = gr.ofdm_correlator(self._occupied_tones, self._fft_length,
-                                             self._cp_length, ks1, ks2)
-        self.ofdm_demod = gr.ofdm_bpsk_demapper(self._occupied_tones)
-
-
-        if options.verbose:
-            self._print_verbage()
-
-        self.fg.connect(self.ofdm_sync, self.fft_demod, self.ofdm_corr, self.ofdm_demod)
-        gr.hier_block.__init__(self, self.fg, self.ofdm_sync, self.ofdm_demod)
-        
-    def bits_per_symbol(self=None):   # staticmethod that's also callable on an instance
-        return 1
-    bits_per_symbol = staticmethod(bits_per_symbol)      # make it a static method.  RTFM
-
-    def add_options(normal, expert):
-        """
-        Adds OFDM-specific options to the Options Parser
-        """
-        expert.add_option("", "--fft-length", type="intx", default=512,
-                          help="set the number of FFT bins [default=%default]")
-        expert.add_option("", "--occupied-tones", type="intx", default=200,
-                          help="set the number of occupied FFT bins [default=%default]")
-        expert.add_option("", "--cp-length", type="intx", default=128,
-                          help="set the number of bits in the cyclic prefix [default=%default]")
-    # Make a static method to call before instantiation
-    add_options = staticmethod(add_options)
-
-    def _print_verbage(self):
-        """
-        Prints information about the OFDM demodulator
-        """
-        print "\nOFDM Demodulator:"
-        print "FFT length:      %3d"   % (self._fft_length)
-        print "Occupied Tones:  %3d"   % (self._occupied_tones)
-        print "CP length:       %3d"   % (self._cp_length)
-
-
-# generated in python using:
-# import random
-# pn = [2.0*random.randint(0,1)-1.0 for i in range(self._occupied_tones)]
-
-known_symbols_200_1 = [1.0, 1.0, -1.0, 1.0, -1.0, -1.0, 1.0, 1.0, 1.0, 1.0, -1.0, 1.0, 1.0, -1.0, 1.0, -1.0, -1.0, 1.0, -1.0, -1.0, 1.0, -1.0, -1.0, 1.0, -1.0, -1.0, 1.0, 1.0, -1.0, 1.0, -1.0, 1.0, -1.0, 1.0, -1.0, -1.0, 1.0, -1.0, 1.0, -1.0, -1.0, -1.0, -1.0, 1.0, 1.0, 1.0, 1.0, -1.0, -1.0, 1.0, -1.0, -1.0, 1.0, -1.0, -1.0, 1.0, -1.0, -1.0, -1.0, -1.0, -1.0, -1.0, 1.0, -1.0, -1.0, -1.0, -1.0, 1.0, -1.0, 1.0, 1.0, -1.0, 1.0, -1.0, 1.0, 1.0, -1.0, 1.0, 1.0, -1.0, 1.0, -1.0, -1.0, -1.0, 1.0, 1.0, 1.0, -1.0, -1.0, 1.0, -1.0, -1.0, -1.0, -1.0, 1.0, 1.0, 1.0, 1.0, 1.0, -1.0, -1.0, 1.0, 1.0, 1.0, -1.0, -1.0, 1.0, 1.0, -1.0, 1.0, 1.0, 1.0, -1.0, -1.0, 1.0, -1.0, 1.0, -1.0, -1.0, -1.0, -1.0, -1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, -1.0, 1.0, -1.0, 1.0, -1.0, 1.0, -1.0, 1.0, -1.0, 1.0, 1.0, 1.0, 1.0, 1.0, -1.0, -1.0, 1.0, 1.0, -1.0, 1.0, 1.0, 1.0, -1.0, 1.0, -1.0, 1.0, 1.0, 1.0, 1.0, 1.0, -1.0, 1.0, 1.0, 1.0, -1.0, -1.0, -1.0, 1.0, -1.0, 1.0, 1.0, 1.0, -1.0, -1.0, -1.0, -1.0, -1.0, 1.0, -1.0, -1.0, -1.0, 1.0, -1.0, -1.0, -1.0, 1.0, 1.0, -1.0, 1.0, 1.0, 1.0, 1.0, 1.0, -1.0, 1.0, 1.0, 1.0, -1.0, 1.0, 1.0, -1.0]
-        
-known_symbols_200_2 = [-1.0, -1.0, -1.0, 1.0, 1.0, 1.0, -1.0, -1.0, -1.0, 1.0, 1.0, -1.0, -1.0, 1.0, 1.0, 1.0, 1.0, -1.0, 1.0, -1.0, 1.0, -1.0, 1.0, -1.0, 1.0, -1.0, -1.0, -1.0, 1.0, -1.0, 1.0, 1.0, 1.0, -1.0, -1.0, -1.0, -1.0, 1.0, -1.0, -1.0, 1.0, 1.0, -1.0, -1.0, 1.0, -1.0, -1.0, 1.0, 1.0, 1.0, 1.0, 1.0, -1.0, 1.0, 1.0, -1.0, -1.0, -1.0, 1.0, -1.0, 1.0, -1.0, 1.0, 1.0, 1.0, 1.0, -1.0, 1.0, -1.0, 1.0, -1.0, -1.0, -1.0, 1.0, -1.0, 1.0, -1.0, 1.0, 1.0, 1.0, -1.0, 1.0, -1.0, 1.0, 1.0, 1.0, -1.0, -1.0, 1.0, 1.0, -1.0, -1.0, -1.0, 1.0, 1.0, 1.0, 1.0, -1.0, -1.0, -1.0, -1.0, -1.0, 1.0, -1.0, 1.0, 1.0, 1.0, 1.0, -1.0, -1.0, 1.0, -1.0, -1.0, 1.0, -1.0, -1.0, 1.0, -1.0, 1.0, 1.0, 1.0, -1.0, -1.0, 1.0, -1.0, -1.0, -1.0, -1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, -1.0, 1.0, 1.0, -1.0, -1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, -1.0, 1.0, -1.0, 1.0, 1.0, 1.0, 1.0, -1.0, 1.0, 1.0, -1.0, 1.0, -1.0, -1.0, -1.0, 1.0, 1.0, -1.0, -1.0, 1.0, 1.0, 1.0, -1.0, 1.0, -1.0, 1.0, -1.0, -1.0, -1.0, 1.0, -1.0, -1.0, -1.0, 1.0, 1.0, 1.0, -1.0, -1.0, 1.0, -1.0, 1.0, -1.0, 1.0, -1.0, -1.0, -1.0, -1.0, -1.0, 1.0, -1.0, -1.0, -1.0, 1.0, 1.0, 1.0]
diff --git a/gnuradio-examples/python/ofdm/ofdm_mod_demod_test.py b/gnuradio-examples/python/ofdm/ofdm_mod_demod_test.py
new file mode 100755
index 000000000..5fe81a538
--- /dev/null
+++ b/gnuradio-examples/python/ofdm/ofdm_mod_demod_test.py
@@ -0,0 +1,179 @@
+#!/usr/bin/env python
+#
+# Copyright 2005, 2006 Free Software Foundation, Inc.
+# 
+# This file is part of GNU Radio
+# 
+# GNU Radio is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2, or (at your option)
+# any later version.
+# 
+# GNU Radio is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+# 
+# You should have received a copy of the GNU General Public License
+# along with GNU Radio; see the file COPYING.  If not, write to
+# the Free Software Foundation, Inc., 51 Franklin Street,
+# Boston, MA 02110-1301, USA.
+# 
+
+from gnuradio import gr, ofdm_packet_utils
+import gnuradio.gr.gr_threading as _threading
+from gnuradio import eng_notation
+from gnuradio.eng_option import eng_option
+from optparse import OptionParser
+
+import random, time, struct, sys, math, os
+
+class my_graph(gr.flow_graph):
+    def __init__(self, callback, options):
+        gr.flow_graph.__init__(self)
+
+        # hard-coded known symbol
+        ks1 = known_symbols_4512_1[0:options.occupied_tones]
+        ks2 = known_symbols_4512_2[0:options.occupied_tones]
+
+        self._rcvd_pktq = gr.msg_queue()
+
+        # accepts messages from the outside world
+        self.ofdm_mapper = gr.ofdm_bpsk_mapper(4, options.occupied_tones, options.fft_length, ks1, ks2)
+        self.ofdm_corr  = gr.ofdm_correlator(options.occupied_tones, options.fft_length, 0, ks1, ks2)
+        self.ofdm_framer = gr.ofdm_frame_sink(self._rcvd_pktq, options.occupied_tones)
+    
+        if 0: # set to 1 to put the correlator in the path to take over the signalling
+            self.connect((self.ofdm_mapper, 0), (self.ofdm_corr, 0))
+            self.connect((self.ofdm_corr, 0), (self.ofdm_framer, 0))
+            self.connect((self.ofdm_corr, 1), (self.ofdm_framer, 1))
+
+            self.connect((self.ofdm_mapper,0), gr.file_sink(gr.sizeof_gr_complex*options.fft_length, "ofdm_mapper.dat"))
+            self.connect((self.ofdm_corr,0), gr.file_sink(gr.sizeof_gr_complex*options.occupied_tones, "ofdm_corr.dat"))
+            self.connect((self.ofdm_corr,1), gr.file_sink(gr.sizeof_char, "ofdm_sig.dat"))
+
+        else:
+            self.connect((self.ofdm_mapper, 0), (self.ofdm_framer, 0))
+            self.connect((self.ofdm_mapper, 1), (self.ofdm_framer, 1))
+
+            self.connect((self.ofdm_mapper,0), gr.file_sink(gr.sizeof_gr_complex*options.fft_length, "ofdm_mapper.dat"))
+            self.connect((self.ofdm_mapper,1), gr.file_sink(gr.sizeof_char, "ofdm_sig.dat"))
+
+        self._watcher = _queue_watcher_thread(self._rcvd_pktq, callback)
+
+    def send_pkt(self, payload='', eof=False):
+        if eof:
+            msg = gr.message(1)
+        else:
+            pkt = ofdm_packet_utils.make_packet(payload, 1, 1, False, whiten=False)
+            msg = gr.message_from_string(pkt)
+        self.ofdm_mapper.msgq().insert_tail(msg)
+
+class _queue_watcher_thread(_threading.Thread):
+    def __init__(self, rcvd_pktq, callback):
+        _threading.Thread.__init__(self)
+        self.setDaemon(1)
+        self.rcvd_pktq = rcvd_pktq
+        self.callback = callback
+        self.keep_running = True
+        self.start()
+
+    def run(self):
+        while self.keep_running:
+            msg = self.rcvd_pktq.delete_head()
+            ok, payload = ofdm_packet_utils.unmake_packet(msg.to_string(), whiten=False)
+            if self.callback:
+                self.callback(ok, payload)
+            
+# /////////////////////////////////////////////////////////////////////////////
+#                                   main
+# /////////////////////////////////////////////////////////////////////////////
+
+def main():
+    ''' Use this program to tie the OFDM modulators straight into the frame sink, with or without
+    the correlator in between. This is for testing of the modulators and demodulators only without
+    receiver and sync functionality.'''
+
+    global n_rcvd, n_right
+        
+    n_rcvd = 0
+    n_right = 0
+        
+    def send_pkt(payload='', eof=False):
+        return fg.send_pkt(payload, eof)
+        
+    def rx_callback(ok, payload):
+        global n_rcvd, n_right
+        n_rcvd += 1
+        (pktno,) = struct.unpack('!H', payload[0:2])
+        if ok:
+            n_right += 1
+        print "ok: %r \t pktno: %d \t n_rcvd: %d \t n_right: %d" % (ok, pktno, n_rcvd, n_right)
+
+        printlst = list()
+        for x in payload[2:]:
+            t = hex(ord(x)).replace('0x', '')
+            if(len(t) == 1):
+                t = '0' + t
+            printlst.append(t)
+        printable = ''.join(printlst)
+
+        print printable
+        print "\n"
+                
+    parser = OptionParser(option_class=eng_option, conflict_handler="resolve")
+    expert = parser.add_option_group("Expert")
+    parser.add_option("-s", "--size", type="eng_float", default=1450,
+                      help="set packet size [default=%default]")
+    parser.add_option("-M", "--megabytes", type="eng_float", default=1.0,
+                      help="set megabytes to transmit [default=%default]")
+    expert.add_option("", "--fft-length", type="intx", default=512,
+                      help="set the number of FFT bins [default=%default]")
+    expert.add_option("", "--occupied-tones", type="intx", default=200,
+                      help="set the number of occupied FFT bins [default=%default]")
+    expert.add_option("", "--cp-length", type="intx", default=128,
+                      help="set the number of bits in the cyclic prefix [default=%default]")
+    expert.add_option("", "--fft-length", type="intx", default=512,
+                      help="set the number of FFT bins [default=%default]")
+    expert.add_option("", "--occupied-tones", type="intx", default=200,
+                      help="set the number of occupied FFT bins [default=%default]")
+    expert.add_option("", "--cp-length", type="intx", default=128,
+                      help="set the number of bits in the cyclic prefix [default=%default]")
+
+    (options, args) = parser.parse_args ()
+
+    # build the graph
+    fg = my_graph(rx_callback, options)
+    
+    fg.start()                       # start flow graph
+    
+    # generate and send packets
+    nbytes = int(1e6 * options.megabytes)
+    n = 0
+    pktno = 0
+    pkt_size = int(options.size)
+
+    while n < nbytes:
+        #r = ''.join([chr(random.randint(0,255)) for i in range(pkt_size-2)])
+        #pkt_contents = struct.pack('!H', pktno) + r
+
+        pkt_contents = struct.pack('!H', pktno) + (pkt_size - 2) * chr(pktno & 0xff)
+
+        send_pkt(pkt_contents)
+        n += pkt_size
+        pktno += 1
+        
+    send_pkt(eof=True)
+    fg.wait()                       # wait for it to finish
+
+known_symbols_4512_1 = [-1, 1, 1, 1, -1, -1,  1, -1, 1, -1, 1, 1, 1, 1, 1, -1, -1, 1, 1, -1, -1, 1, 1, -1, 1, -1, 1, -1, 1, 1, -1, -1, 1, 1, 1, 1, -1, 1, 1, -1, -1, 1, 1, -1, -1, 1, -1, 1, -1, -1, 1, -1, 1, 1, 1, 1, 1, 1, 1, -1, -1, -1, 1, -1, 1, 1, -1, 1, 1, 1, 1, 1, -1, -1, -1, 1, 1, -1, -1, 1, -1, -1, 1, 1, -1, 1, -1, -1, -1, -1, 1, 1, -1, 1, 1, 1, 1, 1, -1, 1, -1, -1, -1, 1, 1, -1, 1, -1, 1, 1, -1, 1, -1, 1, 1, -1, 1, 1, 1, -1, -1, -1, 1, -1, -1, -1, 1, 1, 1, -1, -1, -1, -1, 1, -1, 1, 1, -1, 1, -1, 1, -1, -1, -1, -1, -1, -1, -1, 1, 1, -1, 1, -1, -1, -1, 1, -1, 1, -1, 1, -1, 1, -1, -1, -1, -1, 1, -1, -1, -1, 1, -1, -1, -1, -1, -1, -1, -1, 1, 1, -1, -1, 1, 1, -1, 1, -1, -1, -1, 1, 1, 1, -1, 1, -1, 1, -1, 1, -1, 1, 1, -1, -1, 1, 1, 1, -1, -1, 1, 1, -1, 1, -1, -1, 1, 1, -1, -1, 1, -1, -1, -1, 1, -1, 1, -1, 1, 1, -1, 1, 1, 1, 1, -1, 1, 1, -1, 1, -1, 1, 1, -1, -1, 1, -1, -1, 1, -1, 1, -1, 1, -1, 1, 1, -1, -1, 1, 1, 1, -1, 1, -1, 1, 1, 1, 1, 1, 1, -1, 1, -1, 1, -1, -1, -1, 1, -1, 1, -1, 1, 1, -1, 1, -1, 1, -1, -1, -1, 1, -1, 1, -1, 1, -1, -1, -1, -1, 1, -1, -1, -1, 1, 1, 1, -1, 1, 1, 1, -1, -1, 1, 1, -1, -1, -1, 1, -1, -1, -1, -1, -1, -1, 1, -1, 1, -1, 1, -1, 1, -1, -1, -1, 1, -1, -1, 1, 1, -1, 1, 1, 1, 1, 1, 1, -1, 1, -1, -1, 1, -1, -1, 1, 1, 1, -1, 1, 1, 1, 1, 1, -1, 1, -1, -1, -1, -1, -1, -1, 1, 1, 1, 1, 1, -1, 1, 1, 1, 1, -1, -1, -1, 1, -1, -1, 1, 1, -1, -1, 1, -1, -1, -1, 1, -1, 1, -1, -1, 1, 1, -1, 1, 1, 1, -1, 1, 1, 1, -1, -1, -1, -1, -1, -1, -1, 1, 1, -1, 1, 1, -1, 1, 1, -1, 1, -1, 1, -1, -1, -1, -1, -1, 1, -1, 1, 1, 1, 1, -1, 1, -1, 1, -1, -1, 1, 1, -1, 1, -1, 1, 1, 1, 1, 1, 1, -1, 1, 1, -1, 1, 1, 1, 1, 1, 1, -1, 1, 1, 1, -1, -1, 1, -1, -1, 1, 1, 1, 1, 1, -1, -1, -1, 1, -1, -1, -1, 1, 1, 1, 1, -1, 1, 1, 1, 1, 1, 1, 1, -1, 1, -1, 1, -1, 1, -1, 1, -1, 1, 1, -1, 1, 1, 1, 1, 1, 1, -1, -1, 1, 1, 1, -1, -1, 1, -1, -1, -1, 1, -1, -1, 1, 1, -1, -1, -1, -1, 1, 1, 1, -1, -1, 1, 1, -1, -1, 1, 1, 1, 1, 1, -1, 1, -1, -1, 1, 1, 1, 1, -1, -1, -1, -1, -1, 1, -1, 1, -1, -1, -1, -1, 1, 1, 1, -1, -1, 1, 1, 1, -1, -1, 1, -1, -1, 1, -1, 1, -1, 1, -1, 1, -1, 1, -1, -1, -1, -1, 1, -1, 1, -1, -1, -1, -1, -1, -1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, -1, 1, -1, 1, 1, -1, 1, -1, -1, -1, 1, -1, 1, -1, 1, -1, -1, -1, -1, 1, -1, 1, -1, 1, -1, 1, -1, -1, -1, 1, 1, 1, 1, 1, 1, 1, -1, -1, -1, -1, -1, 1, -1, -1, -1, 1, -1, -1, -1, -1, -1, -1, -1, 1, -1, 1, 1, -1, -1, -1, -1, 1, -1, -1, 1, -1, -1, 1, -1, -1, -1, 1, 1, 1, 1, 1, -1, -1, 1, -1, -1, -1, -1, -1, -1, -1, -1, 1, -1, -1, -1, 1, -1, 1, 1, -1, -1, 1, -1, -1, -1, -1, 1, 1, -1, -1, 1, -1, -1, -1, -1, -1, -1, -1, 1, -1, -1, 1, 1, -1, 1, -1, -1, -1, -1, -1, 1, -1, -1, -1, 1, 1, -1, 1, 1, -1, 1, -1, 1, -1, -1, -1, -1, 1, 1, -1, 1, 1, -1, 1, -1, -1, -1, -1, -1, -1, -1, 1, 1, 1, 1, 1, -1, -1, -1, -1, 1, 1, 1, 1, -1, -1, -1, 1, -1, 1, -1, 1, 1, 1, 1, -1, -1, 1, 1, -1, 1, -1, 1, -1, 1, -1, -1, 1, 1, 1, 1, 1, 1, 1, 1, -1, 1, -1, -1, 1, -1, -1, 1, -1, 1, 1, 1, 1, 1, 1, 1, -1, 1, -1, 1, 1, -1, 1, -1, 1, 1, 1, 1, 1, -1, -1, -1, -1, 1, -1, -1, 1, -1, 1, -1, 1, -1, -1, -1, -1, -1, 1, 1, 1, -1, 1, 1, -1, 1, 1, 1, -1, -1, 1, -1, -1, -1, -1, 1, -1, 1, 1, -1, -1, -1, -1, 1, -1, -1, 1, -1, 1, -1, -1, -1, 1, -1, -1, -1, 1, 1, -1, -1, 1, -1, -1, -1, -1, -1, 1, 1, -1, 1, -1, -1, 1, 1, -1, -1, -1, 1, 1, -1, -1, -1, 1, 1, -1, 1, -1, -1, 1, 1, 1, 1, 1, -1, 1, -1, 1, 1, -1, -1, 1, -1, 1, -1, 1, 1, -1, 1, -1, -1, 1, -1, 1, -1, -1, -1, -1, -1, 1, -1, -1, 1, 1, 1, 1, 1, -1, -1, 1, 1, 1, -1, 1, -1, 1, -1, 1, 1, 1, -1, 1, 1, -1, 1, 1, -1, 1, 1, 1, 1, -1, 1, 1, -1, -1, -1, 1, 1, -1, 1, 1, -1, 1, -1, -1, 1, 1, -1, 1, 1, 1, -1, -1, 1, -1, 1, -1, 1, 1, -1, 1, -1, 1, -1, 1, -1, 1, 1, 1, -1, -1, -1, 1, 1, 1, -1, 1, -1, 1, -1, 1, 1, 1, 1, 1, 1, 1, -1, 1, -1, 1, -1, -1, -1, 1, -1, 1, 1, 1, -1, 1, -1, 1, -1, -1, 1, -1, 1, 1, 1, 1, 1, -1, 1, 1, -1, -1, -1, 1, -1, 1, 1, -1, 1, -1, 1, 1, 1, 1, -1, -1, -1, 1, 1, -1, -1, -1, -1, -1, -1, -1, 1, -1, -1, -1, 1, 1, 1, 1, 1, -1, -1, 1, -1, 1, -1, 1, 1, -1, 1, 1, -1, 1, -1, -1, 1, 1, -1, -1, -1, 1, -1, 1, -1, -1, 1, 1, 1, 1, 1, -1, 1, -1, 1, -1, 1, 1, -1, -1, 1, 1, 1, 1, 1, 1, -1, 1, -1, -1, -1, -1, -1, -1, 1, -1, 1, -1, 1, -1, -1, -1, -1, -1, -1, -1, 1, 1, 1, 1, 1, -1, 1, -1, 1, 1, 1, 1, 1, 1, -1, -1, 1, 1, 1, 1, -1, -1, 1, -1, -1, 1, -1, -1, -1, 1, -1, 1, -1, -1, 1, 1, 1, 1, -1, 1, -1, 1, -1, 1, -1, 1, -1, -1, -1, -1, 1, -1, -1, -1, -1, 1, -1, 1, 1, -1, -1, -1, 1, -1, -1, -1, 1, 1, 1, 1, 1, 1, 1, 1, -1, -1, -1, 1, 1, 1, -1, 1, -1, 1, -1, -1, -1, 1, -1, 1, -1, -1, 1, -1, -1, -1, -1, 1, 1, 1, -1, -1, 1, 1, -1, -1, 1, -1, -1, -1, -1, -1, -1, -1, -1, 1, -1, 1, -1, 1, -1, -1, -1, 1, 1, 1, 1, 1, 1, -1, 1, -1, -1, 1, 1, 1, 1, -1, 1, 1, -1, 1, 1, -1, -1, -1, 1, 1, -1, -1, -1, 1, -1, 1, 1, 1, 1, -1, -1, 1, 1, 1, -1, 1, 1, -1, 1, -1, 1, 1, -1, -1, 1, 1, 1, 1, -1, -1, 1, -1, -1, 1, -1, -1, 1, -1, 1, -1, -1, 1, 1, 1, -1, -1, 1, 1, -1, -1, -1, -1, 1, -1, -1, -1, 1, -1, -1, -1, -1, 1, 1, -1, -1, 1, -1, -1, -1, -1, -1, 1, -1, -1, 1, 1, -1, 1, 1, 1, -1, -1, -1, 1, -1, -1, 1, -1, 1, 1, -1, -1, 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-1, -1, -1, -1, 1, -1, 1, -1, -1, 1, -1, 1, 1, -1, 1, -1, 1, 1, 1, -1, -1, 1, -1, -1, -1, 1, -1, -1, -1, 1, 1, 1, 1, 1, 1, -1, -1, -1, 1, 1, -1, 1, -1, -1, -1, 1, 1, 1, 1, 1, 1, -1, -1, 1, -1, 1, 1, -1, 1, 1, -1, -1, 1, 1, -1, 1, -1, -1, -1, -1, -1, -1, -1, 1, -1, 1, -1, -1, 1, -1, -1, -1, 1, -1, -1, 1, -1, -1, 1, 1, -1, 1, 1, -1, -1, 1, -1, -1, -1, -1, 1, -1, -1, -1, 1, -1, 1, -1, -1, 1, 1, -1, -1, 1, 1, -1, 1, 1, -1, 1, -1, 1, -1, -1, 1, -1, -1, 1, 1, -1, -1, -1, 1, 1, -1, -1, -1, 1, -1, 1, 1, -1, 1, -1, 1, 1, 1, 1, -1, -1, -1, 1, 1, -1, 1, -1, -1, 1, -1, 1, -1, -1, 1, 1, -1, 1, -1, -1, 1, 1, 1, -1, 1, -1, -1, -1, -1, -1, 1, -1, 1, -1, 1, -1, -1, 1, -1, 1, 1, -1, -1, -1, -1, -1, 1, 1, -1, 1, 1, -1, 1, 1, 1, 1, -1, -1, -1, 1, 1, 1, 1, 1, 1, -1, 1, 1, 1, 1, -1, -1, -1, -1, -1, -1, -1, 1, -1, 1, -1, -1, 1, -1, -1, 1, -1, 1, 1, -1, 1, 1, 1, 1, 1, -1, 1, -1, -1, 1, 1, -1, -1, -1, 1, 1, 1, 1, -1, -1, 1, -1, 1, 1, -1, 1, -1, 1, 1, -1, 1, 1, -1, -1, -1, 1, -1, 1, 1, -1, 1, -1, 1, -1, -1, 1, -1, -1, 1, -1, 1, -1, 1, -1, -1, 1, 1, 1, -1, -1, 1, 1, 1, 1, 1, -1, -1, -1, 1, 1, 1, -1, -1, -1, 1, 1, 1, 1, -1, 1, 1, 1, -1, 1, -1, -1, -1, -1, -1, 1, -1, -1, -1, -1, -1, -1, -1, 1, -1, -1, -1, 1, -1, 1, -1, 1, 1, 1, 1, 1, -1, 1, -1, 1, 1, 1, 1, 1, 1, 1, 1, -1, 1, -1, -1, 1, -1, -1, -1, 1, -1, -1, 1, -1, 1, 1, -1, 1, -1, 1, -1, 1, 1, 1, 1, -1, 1, -1, -1, 1, 1, 1, -1, 1, 1, 1, -1, 1, 1, 1, 1, -1, 1, -1, 1, 1, 1, -1, 1, -1, 1, 1, -1, 1, -1, 1, -1, 1, 1, -1, -1, 1, -1, -1, 1, 1, -1, -1, 1, 1, -1, 1, -1, -1, -1, 1, -1, 1, 1, -1, 1, 1, -1, 1, -1, 1, 1, -1, -1, 1, -1, -1, -1, 1, -1, -1, -1, 1, 1, 1, -1, -1, 1, -1, 1, 1, 1, 1, 1, 1, 1, 1, 1, -1, -1, 1, -1, 1, -1, 1, 1, 1, -1, 1, -1, -1, -1, 1, -1, -1, -1, 1, -1, 1, 1, 1, 1, 1, 1, 1, 1, -1, -1, 1, -1, -1, 1, 1, -1, 1, -1, -1, 1, -1, -1, -1, 1, -1, -1, 1, 1, -1, -1, -1, 1, -1, -1, 1, -1, 1, 1, 1, 1, 1, -1, 1, -1, -1, 1, 1, 1, -1, -1, -1, 1, 1, 1, 1, -1, -1, 1, -1, 1, 1, -1, -1, -1, -1, -1, 1, 1, 1, 1, 1, -1, 1, -1, -1, -1, -1, 1, -1, 1, -1, -1, -1, -1, 1, -1, 1, 1, -1, 1, 1, -1, 1, 1, 1, -1, 1, -1, -1, 1, 1, -1, 1, -1, -1, -1, -1, 1, -1, -1, 1, -1, 1, -1, -1, -1, 1, -1, -1, 1, -1, 1, 1, -1, -1, -1, -1, 1, 1, -1, 1, 1, 1, 1, 1, 1, 1, 1, -1, 1, 1, 1, 1, -1, 1, -1, 1, 1, -1, 1, -1, 1, 1, -1, 1, 1, -1, 1, -1, -1, 1, -1, -1, -1, -1, -1, -1, 1, 1, 1, -1, -1, 1, 1, 1, -1, -1, 1, -1, 1, 1, 1, 1, 1, -1, 1, 1, -1, -1, -1, -1, 1, 1, 1, -1, 1, 1, -1, -1, -1, 1, -1, 1, 1, 1, -1, 1, 1, -1, 1, 1, -1, 1, 1, 1, -1, -1, 1, 1, -1, 1, -1, -1, -1, 1, 1, 1, -1, -1, 1, 1, -1, 1, 1, 1, 1, -1, -1, -1, -1, 1, -1, 1, 1, -1, -1, -1, 1, 1, -1, -1, 1, 1, -1, 1, -1, -1, 1, -1, -1, 1, 1, -1, -1, 1, 1, -1, -1, 1, -1, 1, -1, 1, 1, 1, 1, -1, -1, -1, -1, -1, -1, -1, -1, 1, 1, 1, 1, -1, -1, -1, -1, 1, -1, 1, 1, 1, -1, 1, -1, -1, -1, 1, -1, -1, -1, -1, 1, -1, 1, 1, -1, 1, 1, -1, 1, 1, -1, -1, -1, -1, 1, 1, -1, 1, 1, -1, 1, 1, -1, 1, -1, 1, 1, -1, 1, -1, 1, -1, -1, 1, -1, 1, 1, -1, -1, 1, -1, -1, -1, -1, -1, 1, -1, 1, -1, 1, -1, -1, 1, 1, 1, -1, -1, 1, -1, 1, -1, -1, -1, 1, 1, -1, -1, 1, 1, 1, 1, -1, -1, -1, -1, -1, 1, -1, 1, -1, -1, 1, -1, -1, -1, -1, -1, 1, -1, -1, -1, 1, -1, -1, -1, 1, -1, 1, -1, 1, 1, -1, -1, 1, -1, 1, 1, 1, 1, -1, -1, -1, 1, 1, 1, -1, 1, -1, -1, 1, -1, 1, -1, -1, -1, -1, -1, -1, -1, -1, 1, -1, 1, -1, -1, -1, -1, -1, -1, 1, -1, 1, -1, 1, 1, 1, -1, -1, 1, -1, -1, 1, 1, -1, -1, 1, 1, -1, -1, -1, 1, 1, 1, -1, 1, 1, 1, 1, 1, 1, -1, 1, 1, -1, 1, -1, 1, -1, 1, -1, -1, 1, -1, -1, 1, -1, -1, 1, 1, 1, -1, -1, 1, -1, -1, -1, -1, -1, 1, 1, 1, 1, -1, -1, -1, 1, -1, -1, 1, 1, 1, 1, -1, 1, 1, 1, 1, -1, 1, 1, -1, -1, -1, 1, -1, 1, -1, -1, 1, -1, -1, 1, 1, -1, 1, -1, 1, -1, 1, 1, -1, -1, -1, -1, -1, -1, -1, 1, -1, -1, 1, -1, 1, -1, 1, 1, 1, 1, -1, -1, -1, 1, 1, -1, -1, 1, 1, 1, 1, 1, 1, -1, -1, 1, -1, 1, 1, 1, 1, 1, 1, -1, -1, 1, -1, -1, 1, 1, -1, 1, 1, 1, 1, 1, -1, 1, 1, 1, 1, -1, 1, -1, -1, 1, 1, -1, -1, -1, -1, -1, -1, 1, -1, 1, -1, 1, 1, 1, -1, -1, 1, -1, 1, 1, 1, 1, 1, 1, 1, -1, 1, 1, 1, 1, 1, -1, -1, 1, -1, 1, 1, -1, 1, -1, 1, 1, -1, 1, 1, -1, -1, 1, -1, -1, -1, -1, -1, 1, -1, 1, -1, 1, 1, -1, 1, -1, 1, -1, -1, -1, 1, -1, 1, -1, -1, -1, -1, 1, -1, 1, 1, -1, 1, -1, -1, 1, -1, -1, -1, 1, 1, -1, -1, -1, -1, 1, -1, -1, 1, 1, 1, 1, -1, -1, -1, 1, -1, -1, -1, -1, 1, 1, 1, 1, 1, -1, -1, 1, 1, -1, -1, 1, 1, -1, 1, 1, -1, -1, -1, 1, -1, -1, -1, -1, -1, -1, 1, -1, -1, 1, 1, -1, -1, -1, -1, -1, 1, 1, -1, 1, 1, 1, 1, -1, 1, -1, -1, -1, 1, 1, -1, 1, -1, 1, 1, -1, -1, 1, -1, 1, 1, -1, 1, 1, 1, 1, 1, 1, -1, -1, -1, 1, -1, -1, 1, 1, -1, -1, -1, -1, -1, -1, -1, 1, -1, -1, 1, -1, 1, -1, 1, -1, 1, 1, 1, 1, -1, -1, -1, 1, 1, -1, 1, -1, -1, -1, -1, -1, 1, 1, 1, 1, 1, -1, -1, 1, -1, 1, -1, -1, -1, -1, -1, 1, 1, -1, -1, 1, 1, -1, -1, 1, -1, 1, 1, 1, 1, -1, -1, 1, 1, -1, -1, -1, 1, -1, -1, -1, 1, 1, 1, 1, -1, -1]
+
+
+if __name__ == '__main__':
+    try:
+        main()
+    except KeyboardInterrupt:
+        pass
+
diff --git a/gnuradio-examples/python/ofdm/ofdm_receiver.py b/gnuradio-examples/python/ofdm/ofdm_receiver.py
deleted file mode 100644
index 467e3af05..000000000
--- a/gnuradio-examples/python/ofdm/ofdm_receiver.py
+++ /dev/null
@@ -1,147 +0,0 @@
-#!/usr/bin/env python
-#
-# Copyright 2004,2005,2006 Free Software Foundation, Inc.
-# 
-# This file is part of GNU Radio
-# 
-# GNU Radio is free software; you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation; either version 2, or (at your option)
-# any later version.
-# 
-# GNU Radio is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-# 
-# You should have received a copy of the GNU General Public License
-# along with GNU Radio; see the file COPYING.  If not, write to
-# the Free Software Foundation, Inc., 51 Franklin Street,
-# Boston, MA 02110-1301, USA.
-# 
-
-import math
-from gnuradio import gr
-from gnuradio import audio
-from gnuradio.eng_option import eng_option
-from optparse import OptionParser
-
-class ofdm_receiver(gr.hier_block):
-    def __init__(self, fg, fft_length, symbol_length, snr):
-        self.input = gr.add_const_cc(0) # Kluge that goes away with hier_block2
-
-        self.fg = fg
-        
-        cpsize = symbol_length - fft_length;
-
-        SNR = 10.0**(snr/10.0)
-        rho = SNR / (SNR + 1.0)
-
-        # ML Sync
-
-        # Energy Detection from ML Sync
-
-        # Create a delay line
-        delayline = [0.0 for i in range(fft_length+1)]
-        delayline[fft_length] = 1.0
-        self.delay = gr.fir_filter_ccf(1,delayline)
-        self.fg.connect(self.input, self.delay)
-
-        # magnitude squared blocks
-        self.magsqrd1 = gr.complex_to_mag_squared()
-        self.magsqrd2 = gr.complex_to_mag_squared()
-        self.adder = gr.add_ff()
-
-        moving_sum_taps = [rho/2 for i in range(cpsize)]
-        self.moving_sum_filter = gr.fir_filter_fff(1,moving_sum_taps)
-        
-        self.fg.connect(self.input,self.magsqrd1)
-        self.fg.connect(self.delay,self.magsqrd2)
-        self.fg.connect(self.magsqrd1,(self.adder,0))
-        self.fg.connect(self.magsqrd2,(self.adder,1))
-        self.fg.connect(self.adder,self.moving_sum_filter)
-        
-
-        # Correlation from ML Sync
-        self.conjg = gr.conjugate_cc();
-        self.mixer = gr.multiply_cc();
-
-        movingsum2_taps = [1.0 for i in range(cpsize)]
-        self.movingsum2 = gr.fir_filter_ccf(1,movingsum2_taps)
-        
-
-        # Correlator data handler
-        self.c2mag = gr.complex_to_mag()
-        self.angle = gr.complex_to_arg()
-        self.fg.connect(self.input,(self.mixer,1))
-        self.fg.connect(self.delay,self.conjg,(self.mixer,0))
-        self.fg.connect(self.mixer,self.movingsum2,self.c2mag)
-        self.fg.connect(self.movingsum2,self.angle)
-             
-        # ML Sync output arg, need to find maximum point of this
-        self.diff = gr.sub_ff()
-        self.fg.connect(self.c2mag,(self.diff,0))
-        self.fg.connect(self.moving_sum_filter,(self.diff,1))
-
-        #ML measurements input to sampler block and detect
-        nco_sensitivity = 1.0/fft_length
-        self.f2c = gr.float_to_complex()
-        self.sampler = gr.ofdm_sampler(fft_length,symbol_length)
-        self.pkt_detect = gr.peak_detector_ff(0.2, 0.25, 30, 0.0001)
-        self.dpll = gr.dpll_ff(float(symbol_length),0.01)
-        self.sample_and_hold = gr.sample_and_hold_ff()
-        self.nco = gr.frequency_modulator_fc(nco_sensitivity)
-        self.inv = gr.multiply_const_ff(-1)
-        self.sigmix = gr.multiply_cc()
-
-        # Mix the signal with an NCO controlled by the sync loop
-        self.fg.connect(self.input, (self.sigmix,0))
-        self.fg.connect(self.nco, (self.sigmix,1))
-        self.fg.connect(self.sigmix, (self.sampler,0))
-
-        sample_trigger = 0
-        if sample_trigger:
-            # for testing
-            peak_null = gr.null_sink(gr.sizeof_float)
-            data = 640*[0,]
-            data[639] = 1
-            peak_trigger = gr.vector_source_f(data, True)
-
-            self.fg.connect(self.pkt_detect, peak_null)
-            self.fg.connect(peak_trigger, self.f2c, (self.sampler,1))
-            self.fg.connect(peak_trigger, (self.sample_and_hold,1))
-            
-        # use the sync loop values to set the sampler and the NCO
-        # self.diff = theta
-        # self.angle = epsilon
-                          
-        self.fg.connect(self.diff, self.pkt_detect)
-        use_dpll = 1
-        if not sample_trigger:
-            if use_dpll:
-                self.fg.connect(self.pkt_detect, self.dpll,self.f2c, (self.sampler,1))
-                self.fg.connect(self.dpll, (self.sample_and_hold,1))
-            if not use_dpll:
-                self.fg.connect(self.pkt_detect, self.f2c, (self.sampler,1))
-                self.fg.connect(self.pkt_detect, (self.sample_and_hold,1))
-            
-        self.fg.connect(self.angle, (self.sample_and_hold,0))
-        self.fg.connect(self.sample_and_hold, self.inv, self.nco)
-        
-
-        if 0:
-            self.fg.connect(self.diff, gr.file_sink(gr.sizeof_float, "theta_f.dat"))
-            self.fg.connect(self.angle, gr.file_sink(gr.sizeof_float, "epsilon_f.dat"))
-            if use_dpll:
-                self.fg.connect(self.dpll, gr.file_sink(gr.sizeof_float, "dpll_pulses.dat"))
-            if sample_trigger:
-                self.fg.connect(peak_trigger, gr.file_sink(gr.sizeof_float, "peaks_f.dat"))
-            else:
-                self.fg.connect(self.pkt_detect, gr.file_sink(gr.sizeof_float, "peaks_f.dat"))
-                
-            self.fg.connect(self.sample_and_hold, gr.file_sink(gr.sizeof_float, "sample_and_hold_f.dat"))
-            self.fg.connect(self.nco, gr.file_sink(gr.sizeof_gr_complex, "nco_c.dat"))
-            self.fg.connect(self.input, gr.file_sink(gr.sizeof_gr_complex, "input_c.dat"))
-            self.fg.connect(self.sigmix, gr.file_sink(gr.sizeof_gr_complex, "output_c.dat"))
-        
-        gr.hier_block.__init__(self, fg, self.input, self.sampler)
diff --git a/gnuradio-examples/python/ofdm/ofdm_sync.m b/gnuradio-examples/python/ofdm/ofdm_sync.m
new file mode 100644
index 000000000..d5df42137
--- /dev/null
+++ b/gnuradio-examples/python/ofdm/ofdm_sync.m
@@ -0,0 +1,28 @@
+%
+
+function [theta, g, g1, k, h] = ofdm_sync(signal,SNR,FFTSIZE,CPLEN)
+
+  rho = SNR/(SNR+1);
+
+  d = abs(signal).^2;
+  g = [ zeros(1,FFTSIZE) signal(1:max(size(signal))-FFTSIZE) ];
+  g1 = conj(g);
+  f = abs(g).^2;
+  c = d + f;
+  moving_sum_taps = rho/2 * ones(1,CPLEN);
+  b = conv(c,moving_sum_taps);
+  b = b(1:max(size(signal)));
+  %b = b(CPLEN:max(size(b)));
+  
+  k = g1 .* signal;
+
+  moving_sum_taps2 = ones(1, CPLEN);
+  h = conv(k,moving_sum_taps2);
+  h = h(1:max(size(signal)));
+  %h = h(CPLEN:max(size(h)));
+  
+  a = abs(h);
+  
+  theta = a-b;
+
+endfunction
diff --git a/gnuradio-examples/python/ofdm/receive_path.py b/gnuradio-examples/python/ofdm/receive_path.py
index 1c9c23844..0e44ffde0 100644
--- a/gnuradio-examples/python/ofdm/receive_path.py
+++ b/gnuradio-examples/python/ofdm/receive_path.py
@@ -28,7 +28,6 @@ import sys
 
 # from current dir
 from pick_bitrate import pick_rx_bitrate
-import ofdm
 
 # /////////////////////////////////////////////////////////////////////////////
 #                              receive path
@@ -43,40 +42,22 @@ class receive_path(gr.hier_block):
         self._log         = options.log
         self._rx_callback = rx_callback      # this callback is fired when there's a packet available
 
-        if 0:
-            
-            chan_coeffs = gr.firdes.low_pass (1.0,                  # gain
-                                              2.0,                  # sampling rate
-                                              bw,                   # midpoint of trans. band
-                                              1*bw,               # width of trans. band
-                                              gr.firdes.WIN_KAISER)   # filter type 
-        else:
-            chan_coeffs = [ 1.0, 0.0, 0 ] 
-        self.chan_filt = gr.fft_filter_ccc(1, chan_coeffs)
-
-        self.ofdm_demod = ofdm.ofdm_demod(fg, options)
-        
         # receiver
-        self.packet_receiver = \
-            blks.demod_ofdm_pkts(fg,
-                                 self.ofdm_demod,
-                                 access_code=None,
-                                 callback=self._rx_callback,
-                                 threshold=-1)
+        self.ofdm_receiver = \
+            blks.demod_ofdm_pkts(fg, options,
+                                 callback=self._rx_callback)
 
         # Carrier Sensing Blocks
-        alpha = 0.001
-        thresh = 30   # in dB, will have to adjust
-        self.probe = gr.probe_avg_mag_sqrd_c(thresh,alpha)
-        fg.connect(self.chan_filt, self.probe)
+        #alpha = 0.001
+        #thresh = 30   # in dB, will have to adjust
+        #self.probe = gr.probe_avg_mag_sqrd_c(thresh,alpha)
+        #fg.connect(self.chan_filt, self.probe)
 
         # Display some information about the setup
         if self._verbose:
             self._print_verbage()
         
-        fg.connect(self.chan_filt, self.packet_receiver)
-        #fg.connect(self.chan_filt, gr.file_sink(gr.sizeof_gr_complex, "ofdmrx_chflt.dat"))
-        gr.hier_block.__init__(self, fg, self.chan_filt, None)
+        gr.hier_block.__init__(self, fg, self.ofdm_receiver, None)
 
     def carrier_sensed(self):
         """
diff --git a/gnuradio-examples/python/ofdm/transmit_path.py b/gnuradio-examples/python/ofdm/transmit_path.py
index 308ec0851..e684c442c 100644
--- a/gnuradio-examples/python/ofdm/transmit_path.py
+++ b/gnuradio-examples/python/ofdm/transmit_path.py
@@ -26,9 +26,6 @@ from gnuradio import eng_notation
 import copy
 import sys
 
-# from current dir
-import ofdm
-
 # /////////////////////////////////////////////////////////////////////////////
 #                              transmit path
 # /////////////////////////////////////////////////////////////////////////////
@@ -44,13 +41,11 @@ class transmit_path(gr.hier_block):
         self._verbose      = options.verbose
         self._tx_amplitude = options.tx_amplitude    # digital amplitude sent to USRP
 
-        self.ofdm_mod = ofdm.ofdm_mod(fg, options)
-        self.packet_transmitter = \
+        self.ofdm_transmitter = \
             blks.mod_ofdm_pkts(fg,
-                               self.ofdm_mod,
-                               access_code=None,
+                               options,
                                msgq_limit=4,
-                               pad_for_usrp=True)
+                               pad_for_usrp=False)
 
         self.amp = gr.multiply_const_cc(1)
         self.set_tx_amplitude(self._tx_amplitude)
@@ -60,7 +55,7 @@ class transmit_path(gr.hier_block):
             self._print_verbage()
 
         # Create and setup transmit path flow graph
-        fg.connect(self.packet_transmitter, self.amp)
+        fg.connect(self.ofdm_transmitter, self.amp)
         gr.hier_block.__init__(self, fg, None, self.amp)
 
     def set_tx_amplitude(self, ampl):
@@ -75,7 +70,7 @@ class transmit_path(gr.hier_block):
         """
         Calls the transmitter method to send a packet
         """
-        return self.packet_transmitter.send_pkt(payload, eof)
+        return self.ofdm_transmitter.send_pkt(payload, eof)
         
     def bitrate(self):
         return self._bitrate
@@ -87,7 +82,7 @@ class transmit_path(gr.hier_block):
         """
         Adds transmitter-specific options to the Options Parser
         """
-        normal.add_option("", "--tx-amplitude", type="eng_float", default=12000, metavar="AMPL",
+        normal.add_option("", "--tx-amplitude", type="eng_float", default=1, metavar="AMPL",
                           help="set transmitter digital amplitude: 0 <= AMPL < 32768 [default=%default]")
         normal.add_option("-v", "--verbose", action="store_true", default=False)
         expert.add_option("", "--log", action="store_true", default=False,