Forum: GNU Radio Modifications in benchmark_rx.py for USRP2

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0db2b83c8c9466edb194423b1798de4a?d=identicon&s=25 Smith L. (Guest)
on 2009-02-26 22:57
(Received via mailing list)
Hi,

I have been trying to use USRP2 as a receiver and USRP1 as a
transmitter.
The benchmark_tx.py file is working well for USRP1 but I did some
modifications to benchmark_rx.py so that it can work on USRP2. But it
didnt
worked out. Can anyone help me with this modifcations so that I can
establish communication between USRP1 and USRP2. Thanks in advance.
--
View this message in context:
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D9b2772a9387f5dbe010dbc0c3a93f8d?d=identicon&s=25 Douglas Geiger (Guest)
on 2009-02-27 18:47
(Received via mailing list)
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Smith L. wrote:
> Hi,
>
> I have been trying to use USRP2 as a receiver and USRP1 as a transmitter.
> The benchmark_tx.py file is working well for USRP1 but I did some
> modifications to benchmark_rx.py so that it can work on USRP2. But it didnt
> worked out. Can anyone help me with this modifcations so that I can
> establish communication between USRP1 and USRP2. Thanks in advance.

 I was finally able to dig up the versions I used a while back for this.
I don't recall if the transmit side really worked, but the receive-side
certainly should.
 You'll want to copy/rename the original receive_path.py and
transmit_path.py, and replace them with the usrp2-versions, and
tunnel_usrp2.py can be used as-is (although - again, I'm not certain the
transmit-portion was working - although it gave no obvious errors).
 Good luck!
 Doug

- --
Doug Geiger
Research Assistant
Communications and Signal Processing Lab
Oklahoma State University
http://cspl.okstate.edu
douglas.geiger@okstate.edu
doug.geiger@ieee.org
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A576b201df57014077494da786319110?d=identicon&s=25 Tom Rondeau (Guest)
on 2009-03-02 01:16
(Received via mailing list)
Smith L. wrote:
> Hi,
>
> I have been trying to use USRP2 as a receiver and USRP1 as a transmitter.
> The benchmark_tx.py file is working well for USRP1 but I did some
> modifications to benchmark_rx.py so that it can work on USRP2. But it didnt
> worked out. Can anyone help me with this modifcations so that I can
> establish communication between USRP1 and USRP2. Thanks in advance.
>

You have to watch out for the different sample rates. When you set the
sample rate in benchmark_tx/rx, it finds the closest sampling rate it
can get through the interpolation/decimation factor in the USRP. Since
the USRP and USRP2 have different speed DACs/ADCs, the exact values are
going to be different.

Run both with the -v option to see what the actual sample rate both the
tx and rx side are using. To fix this, either try to find a rate that
works for both USRP and USRP2, or, and this is a better solution, use a
blks2.rational_resampler_ccf to resample to achieve closer sampling
rates in both tx and rx.

Tom
0db2b83c8c9466edb194423b1798de4a?d=identicon&s=25 Smith L. (Guest)
on 2009-03-04 23:44
(Received via mailing list)
Hi Tom,


I tried it out but its not working. I am always getting an S which means
overrun. I am attaching the all the files that I have used to make USRP2
work as receiver. I have made no changes to benchmark_tx.py as it is
used
for USRP1 and its working correctly.

benchmark_rx.py:


#!/usr/bin/env python
#
# Copyright 2005,2006,2007 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 3, 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, gru, modulation_utils
from gnuradio import usrp2
from gnuradio import eng_notation
from gnuradio.eng_option import eng_option
from optparse import OptionParser

import random
import struct
import sys

# from current dir
from receive_path_usrp2 import receive_path
import fusb_options

#import os
#print os.getpid()
#raw_input('Attach and press enter: ')

class my_top_block(gr.top_block):
    def __init__(self, demodulator, rx_callback, options):
        gr.top_block.__init__(self)
        self.rxpath = receive_path(demodulator, rx_callback, options)
        self.connect(self.rxpath)

#
/////////////////////////////////////////////////////////////////////////////
#                                   main
#
/////////////////////////////////////////////////////////////////////////////

global n_rcvd, n_right

def main():
    global n_rcvd, n_right

    n_rcvd = 0
    n_right = 0

    def rx_callback(ok, payload):
        global n_rcvd, n_right
        (pktno,) = struct.unpack('!H', payload[0:2])
        n_rcvd += 1
        if ok:
            n_right += 1

        print "ok = %5s  pktno = %4d  n_rcvd = %4d  n_right = %4d" % (
            ok, pktno, n_rcvd, n_right)


    demods = modulation_utils.type_1_demods()

    # Create Options Parser:
    parser = OptionParser (option_class=eng_option,
conflict_handler="resolve")
    expert_grp = parser.add_option_group("Expert")

    parser.add_option("-m", "--modulation", type="choice",
choices=demods.keys(),
                      default='gmsk',
                      help="Select modulation from: %s
[default=%%default]"
                            % (', '.join(demods.keys()),))

    receive_path.add_options(parser, expert_grp)

    for mod in demods.values():
        mod.add_options(expert_grp)

    fusb_options.add_options(expert_grp)
    (options, args) = parser.parse_args ()

    if len(args) != 0:
        parser.print_help(sys.stderr)
        sys.exit(1)

    if options.rx_freq is None:
        sys.stderr.write("You must specify -f FREQ or --freq FREQ\n")
        parser.print_help(sys.stderr)
        sys.exit(1)


    # build the graph
    tb = my_top_block(demods[options.modulation], rx_callback, options)

    r = gr.enable_realtime_scheduling()
    if r != gr.RT_OK:
        print "Warning: Failed to enable realtime scheduling."

    tb.start()        # start flow graph
    tb.wait()         # wait for it to finish

if __name__ == '__main__':
    try:
        main()
    except KeyboardInterrupt:
        pass


receive_path.py:


#!/usr/bin/env python
#
# Copyright 2005,2006,2007 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 3, 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, gru, blks2
from gnuradio import usrp2
from gnuradio import eng_notation
import copy
import sys

# from current dir
from pick_bitrate import pick_rx_bitrate

#
/////////////////////////////////////////////////////////////////////////////
#                              receive path
#
/////////////////////////////////////////////////////////////////////////////

class receive_path(gr.hier_block2):
    def __init__(self, demod_class, rx_callback, options):

  gr.hier_block2.__init__(self, "receive_path",
                                gr.io_signature(0, 0, 0), # Input
signature
                                gr.io_signature(0, 0, 0)) # Output
signature

        options = copy.copy(options)    # make a copy so we can
destructively modify

        self._interface          = options.interface           # the
USRP
board attached
  self._mac_addr           = options.mac_addr
        self._verbose            = options.verbose
        self._rx_freq            = options.rx_freq         # receiver's
center frequency
        self._rx_gain            = options.rx_gain         # receiver's
gain
        #self._rx_subdev_spec     = options.rx_subdev_spec  #
daughterboard
to use
        self._bitrate            = options.bitrate         # desired bit
rate
        self._decim              = options.decim           # Decimating
rate
for the USRP (prelim)
        self._samples_per_symbol = options.samples_per_symbol  # desired
samples/symbol
        self._fusb_block_size    = options.fusb_block_size # usb info
for
USRP
        self._fusb_nblocks       = options.fusb_nblocks    # usb info
for
USRP

        self._rx_callback   = rx_callback      # this callback is fired
when
there's a packet available
        self._demod_class   = demod_class      # the demodulator_class
we're
using

        if self._rx_freq is None:
            sys.stderr.write("-f FREQ or --freq FREQ or --rx-freq FREQ
must
be specified\n")
            raise SystemExit

        # Set up USRP source; also adjusts decim, samples_per_symbol,
and
bitrate
        self._setup_usrp_source()

        g = self.u.gain_range()
        if options.show_rx_gain_range:
            print "Rx Gain Range: minimum = %g, maximum = %g, step size
=
%g" \
                  % (g[0], g[1], g[2])

        self.set_gain(options.rx_gain)

        self.set_auto_tr(True)                 # enable Auto
Transmit/Receive switching

        # Set RF frequency
        ok = self.set_freq(self._rx_freq)
        if not ok:
            print "Failed to set Rx frequency to %s" %
(eng_notation.num_to_str(self._rx_freq))
            raise ValueError, eng_notation.num_to_str(self._rx_freq)

        # copy the final answers back into options for use by
demodulator
        options.samples_per_symbol = self._samples_per_symbol
        options.bitrate = self._bitrate
        options.decim = self._decim

        # Get demod_kwargs
        demod_kwargs =
self._demod_class.extract_kwargs_from_options(options)
  # Fix USRP2 -> USRP1 scaling
  self.scale = gr.multiply_const_cc(32768)
        # Design filter to get actual channel we want
        sw_decim = 1
        chan_coeffs = gr.firdes.low_pass (1.0,                  # gain
                                          sw_decim *
self._samples_per_symbol, # sampling rate
                                          1.0,                  #
midpoint
of trans. band
                                          0.5,                  # width
of
trans. band
                                          gr.firdes.WIN_HANN)   # filter
type

        # Decimating channel filter
        # complex in and out, float taps
        self.chan_filt = gr.fft_filter_ccc(sw_decim, chan_coeffs)
        #self.chan_filt = gr.fir_filter_ccf(sw_decim, chan_coeffs)

        # receiver
        self.packet_receiver = \
            blks2.demod_pkts(self._demod_class(**demod_kwargs),
                             access_code=None,
                             callback=self._rx_callback,
                             threshold=-1)

        # Carrier Sensing Blocks
        alpha = 0.001
        thresh = 30   # in dB, will have to adjust

        if options.log_rx_power == True:
            self.probe = gr.probe_avg_mag_sqrd_cf(thresh,alpha)
            self.power_sink = gr.file_sink(gr.sizeof_float,
"rxpower.dat")
            self.connect(self.chan_filt, self.probe, self.power_sink)
        else:
            self.probe = gr.probe_avg_mag_sqrd_c(thresh,alpha)
            self.connect(self.chan_filt, self.probe)

        # Display some information about the setup
        if self._verbose:
            self._print_verbage()

        self.connect(self.u, self.scale, self.chan_filt,
self.packet_receiver)

    def _setup_usrp_source(self):
        self.u = usrp2.source_32fc (self._interface, self._mac_addr)
        adc_rate = self.u.adc_rate()

        # derive values of bitrate, samples_per_symbol, and decim from
desired info
        (self._bitrate, self._samples_per_symbol, self._decim) = \
            pick_rx_bitrate(self._bitrate,
self._demod_class.bits_per_symbol(), \
                            self._samples_per_symbol, self._decim,
adc_rate)

        self.u.set_decim(self._decim)

        # determine the daughterboard subdevice we're using
        #if self._rx_subdev_spec is None:
        #    self._rx_subdev_spec = usrp.pick_rx_subdevice(self.u)
        #self.subdev = usrp.selected_subdev(self.u,
self._rx_subdev_spec)

        #self.u.set_mux(usrp.determine_rx_mux_value(self.u,
self._rx_subdev_spec))

    def set_freq(self, target_freq):
        """
        Set the center frequency we're interested in.

        @param target_freq: frequency in Hz
        @rypte: bool

        Tuning is a two step process.  First we ask the front-end to
        tune as close to the desired frequency as it can.  Then we use
        the result of that operation and our target_frequency to
        determine the value for the digital up converter.
        """
        r = self.u.set_center_freq(target_freq)
        if r:
            return True

        return False

    def set_gain(self, gain):
        """
        Sets the analog gain in the USRP
        """
        if gain is None:
            r = self.u.gain_range()
            gain = (r[0] + r[1])/2               # set gain to midpoint
        self.gain = gain
        return self.u.set_gain(gain)

    def set_auto_tr(self, enable):
        #return self.u.set_auto_tr(enable)
  return

    def bitrate(self):
        return self._bitrate

    def samples_per_symbol(self):
        return self._samples_per_symbol

    def decim(self):
        return self._decim

    def carrier_sensed(self):
        """
        Return True if we think carrier is present.
        """
        #return self.probe.level() > X
        return self.probe.unmuted()

    def carrier_threshold(self):
        """
        Return current setting in dB.
        """
        return self.probe.threshold()

    def set_carrier_threshold(self, threshold_in_db):
        """
        Set carrier threshold.

        @param threshold_in_db: set detection threshold
        @type threshold_in_db:  float (dB)
        """
        self.probe.set_threshold(threshold_in_db)


    def add_options(normal, expert):
        """
        Adds receiver-specific options to the Options Parser
        """
        add_freq_option(normal)
        if not normal.has_option("--bitrate"):
            normal.add_option("-r", "--bitrate", type="eng_float",
default=None,
                              help="specify bitrate.  samples-per-symbol
and
interp/decim will be derived.")
        normal.add_option("-e", "--interface", type="string",
default="eth0",
                          help="select Ethernet interface, default is
eth0")
        normal.add_option("-m", "--mac-addr", type="string", default="",
                          help="select USRP by MAC address, default is
auto-select")
        #normal.add_option("-R", "--rx-subdev-spec", type="subdev",
default=None,
        #                  help="select USRP Rx side A or B")
        normal.add_option("", "--rx-gain", type="eng_float",
default=None,
metavar="GAIN",
                          help="set receiver gain in dB
[default=midpoint].
See also --show-rx-gain-range")
        normal.add_option("", "--show-rx-gain-range",
action="store_true",
default=False,
                          help="print min and max Rx gain available on
selected daughterboard")
        normal.add_option("-v", "--verbose", action="store_true",
default=False)
        expert.add_option("-S", "--samples-per-symbol", type="int",
default=None,
                          help="set samples/symbol [default=%default]")
        expert.add_option("", "--rx-freq", type="eng_float",
default=None,
                          help="set Rx frequency to FREQ
[default=%default]", metavar="FREQ")
        expert.add_option("-d", "--decim", type="intx", default=None,
                          help="set fpga decimation rate to DECIM
[default=%default]")
        expert.add_option("", "--log", action="store_true",
default=False,
                          help="Log all parts of flow graph to files
(CAUTION: lots of data)")
        expert.add_option("", "--log-rx-power", action="store_true",
default=False,
                          help="Log receive signal power to file
(CAUTION:
lots of data)")

    # Make a static method to call before instantiation
    add_options = staticmethod(add_options)


    def _print_verbage(self):
        """
        Prints information about the receive path
        """
        print "\nReceive Path:"
        print "Using RX d'board %s"    % (self.u.daughterboard_id(),)
        print "Rx gain:         %g"    % (self.gain,)
        print "modulation:      %s"    % (self._demod_class.__name__)
        print "bitrate:         %sb/s" %
(eng_notation.num_to_str(self._bitrate))
        print "samples/symbol:  %3d"   % (self._samples_per_symbol)
        print "decim:           %3d"   % (self._decim)
        print "Rx Frequency:    %s"    %
(eng_notation.num_to_str(self._rx_freq))
        # print "Rx Frequency:    %f"    % (self._rx_freq)

    def __del__(self):
        # Avoid weak reference error
        #del self.subdev
  return

def add_freq_option(parser):
    """
    Hackery that has the -f / --freq option set both tx_freq and rx_freq
    """
    def freq_callback(option, opt_str, value, parser):
        parser.values.rx_freq = value
        parser.values.tx_freq = value

    if not parser.has_option('--freq'):
        parser.add_option('-f', '--freq', type="eng_float",
                          action="callback", callback=freq_callback,
                          help="set Tx and/or Rx frequency to FREQ
[default=%default]",
                          metavar="FREQ")


tunnel_usrp2.py:


#!/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 3, 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.
#


#
/////////////////////////////////////////////////////////////////////////////
#
#    This code sets up up a virtual ethernet interface (typically gr0),
#    and relays packets between the interface and the GNU Radio PHY+MAC
#
#    What this means in plain language, is that if you've got a couple
#    of USRPs on different machines, and if you run this code on those
#    machines, you can talk between them using normal TCP/IP networking.
#
#
/////////////////////////////////////////////////////////////////////////////


from gnuradio import gr, gru, modulation_utils
from gnuradio import usrp2
from gnuradio import eng_notation
from gnuradio.eng_option import eng_option
from optparse import OptionParser

import random
import time
import struct
import sys
import os

# from current dir
from transmit_path import transmit_path
from receive_path import receive_path
import fusb_options

#print os.getpid()
#raw_input('Attach and press enter')


#
/////////////////////////////////////////////////////////////////////////////
#
#   Use the Universal TUN/TAP device driver to move packets to/from
kernel
#
#   See /usr/src/linux/Documentation/networking/tuntap.txt
#
#
/////////////////////////////////////////////////////////////////////////////

# Linux specific...
# TUNSETIFF ifr flags from <linux/tun_if.h>

IFF_TUN    = 0x0001   # tunnel IP packets
IFF_TAP    = 0x0002   # tunnel ethernet frames
IFF_NO_PI  = 0x1000   # don't pass extra packet info
IFF_ONE_QUEUE  = 0x2000   # beats me ;)

def open_tun_interface(tun_device_filename):
    from fcntl import ioctl

    mode = IFF_TAP | IFF_NO_PI
    TUNSETIFF = 0x400454ca

    tun = os.open(tun_device_filename, os.O_RDWR)
    ifs = ioctl(tun, TUNSETIFF, struct.pack("16sH", "gr%d", mode))
    ifname = ifs[:16].strip("\x00")
    return (tun, ifname)


#
/////////////////////////////////////////////////////////////////////////////
#                             the flow graph
#
/////////////////////////////////////////////////////////////////////////////

class my_top_block(gr.top_block):

    def __init__(self, mod_class, demod_class,
                 rx_callback, options):

        gr.top_block.__init__(self)
        self.txpath = transmit_path(mod_class, options)
        self.rxpath = receive_path(demod_class, rx_callback, options)
  self.connect(self.txpath);
  self.connect(self.rxpath);

    def send_pkt(self, payload='', eof=False):
        return self.txpath.send_pkt(payload, eof)

    def carrier_sensed(self):
        """
        Return True if the receive path thinks there's carrier
        """
        return self.rxpath.carrier_sensed()


#
/////////////////////////////////////////////////////////////////////////////
#                           Carrier Sense MAC
#
/////////////////////////////////////////////////////////////////////////////

class cs_mac(object):
    """
    Prototype carrier sense MAC

    Reads packets from the TUN/TAP interface, and sends them to the PHY.
    Receives packets from the PHY via phy_rx_callback, and sends them
    into the TUN/TAP interface.

    Of course, we're not restricted to getting packets via TUN/TAP, this
    is just an example.
    """
    def __init__(self, tun_fd, verbose=False):
        self.tun_fd = tun_fd       # file descriptor for TUN/TAP
interface
        self.verbose = verbose
        self.tb = None             # top block (access to PHY)

    def set_top_block(self, tb):
        self.tb = tb

    def phy_rx_callback(self, ok, payload):
        """
        Invoked by thread associated with PHY to pass received packet
up.

        @param ok: bool indicating whether payload CRC was OK
        @param payload: contents of the packet (string)
        """
        if self.verbose:
            print "Rx: ok = %r  len(payload) = %4d" % (ok, len(payload))
        if ok:
            os.write(self.tun_fd, payload)

    def main_loop(self):
        """
        Main loop for MAC.
        Only returns if we get an error reading from TUN.

        FIXME: may want to check for EINTR and EAGAIN and reissue read
        """
        min_delay = 0.001               # seconds

        while 1:
            payload = os.read(self.tun_fd, 10*1024)
            if not payload:
                self.tb.send_pkt(eof=True)
                break

            if self.verbose:
                print "Tx: len(payload) = %4d" % (len(payload),)

            delay = min_delay
            while self.tb.carrier_sensed():
                sys.stderr.write('B')
                time.sleep(delay)
                if delay < 0.050:
                    delay = delay * 2       # exponential back-off

            self.tb.send_pkt(payload)


#
/////////////////////////////////////////////////////////////////////////////
#                                   main
#
/////////////////////////////////////////////////////////////////////////////

def main():

    mods = modulation_utils.type_1_mods()
    demods = modulation_utils.type_1_demods()

    parser = OptionParser (option_class=eng_option,
conflict_handler="resolve")
    expert_grp = parser.add_option_group("Expert")

    parser.add_option("-m", "--modulation", type="choice",
choices=mods.keys(),
                      default='gmsk',
                      help="Select modulation from: %s
[default=%%default]"
                            % (', '.join(mods.keys()),))

    parser.add_option("-v","--verbose", action="store_true",
default=False)
    expert_grp.add_option("-c", "--carrier-threshold", type="eng_float",
default=30,
                          help="set carrier detect threshold (dB)
[default=%default]")
    expert_grp.add_option("","--tun-device-filename",
default="/dev/net/tun",
                          help="path to tun device file
[default=%default]")

    transmit_path.add_options(parser, expert_grp)
    receive_path.add_options(parser, expert_grp)

    for mod in mods.values():
        mod.add_options(expert_grp)

    for demod in demods.values():
        demod.add_options(expert_grp)

    fusb_options.add_options(expert_grp)

    (options, args) = parser.parse_args ()
    if len(args) != 0:
        parser.print_help(sys.stderr)
        sys.exit(1)

    if options.rx_freq is None or options.tx_freq is None:
        sys.stderr.write("You must specify -f FREQ or --freq FREQ\n")
        parser.print_help(sys.stderr)
        sys.exit(1)

    # open the TUN/TAP interface
    (tun_fd, tun_ifname) =
open_tun_interface(options.tun_device_filename)

    # Attempt to enable realtime scheduling
    r = gr.enable_realtime_scheduling()
    if r == gr.RT_OK:
        realtime = True
    else:
        realtime = False
        print "Note: failed to enable realtime scheduling"


    # If the user hasn't set the fusb_* parameters on the command line,
    # pick some values that will reduce latency.

    if options.fusb_block_size == 0 and options.fusb_nblocks == 0:
        if realtime:                        # be more aggressive
            options.fusb_block_size = gr.prefs().get_long('fusb',
'rt_block_size', 1024)
            options.fusb_nblocks    = gr.prefs().get_long('fusb',
'rt_nblocks', 16)
        else:
            options.fusb_block_size = gr.prefs().get_long('fusb',
'block_size', 4096)
            options.fusb_nblocks    = gr.prefs().get_long('fusb',
'nblocks',
16)

    #print "fusb_block_size =", options.fusb_block_size
    #print "fusb_nblocks    =", options.fusb_nblocks

    # instantiate the MAC
    mac = cs_mac(tun_fd, verbose=True)


    # build the graph (PHY)
    tb = my_top_block(mods[options.modulation],
                      demods[options.modulation],
                      mac.phy_rx_callback,
                      options)

    mac.set_top_block(tb)    # give the MAC a handle for the PHY

    if tb.txpath.bitrate() != tb.rxpath.bitrate():
        print "WARNING: Transmit bitrate = %sb/sec, Receive bitrate =
%sb/sec" % (
            eng_notation.num_to_str(tb.txpath.bitrate()),
            eng_notation.num_to_str(tb.rxpath.bitrate()))

    print "modulation:     %s"   % (options.modulation,)
    print "freq:           %s"      %
(eng_notation.num_to_str(options.tx_freq))
    print "bitrate:        %sb/sec" %
(eng_notation.num_to_str(tb.txpath.bitrate()),)
    print "samples/symbol: %3d" % (tb.txpath.samples_per_symbol(),)
    #print "interp:         %3d" % (tb.txpath.interp(),)
    #print "decim:          %3d" % (tb.rxpath.decim(),)

    tb.rxpath.set_carrier_threshold(options.carrier_threshold)
    print "Carrier sense threshold:", options.carrier_threshold, "dB"

    print
    print "Allocated virtual ethernet interface: %s" % (tun_ifname,)
    print "You must now use ifconfig to set its IP address. E.g.,"
    print
    print "  $ sudo ifconfig %s 192.168.200.1" % (tun_ifname,)
    print
    print "Be sure to use a different address in the same subnet for
each
machine."
    print


    tb.start()    # Start executing the flow graph (runs in separate
threads)

    mac.main_loop()    # don't expect this to return...

    tb.stop()     # but if it does, tell flow graph to stop.
    tb.wait()     # wait for it to finish


if __name__ == '__main__':
    try:
        main()
    except KeyboardInterrupt:
        pass

Please let me know if I am missing out something in the code. Also can
you
let me know where am I suppose to use blks2.rational_resampler_ccf in
the
code. Thanks in advance.

With regards,
Smith

Tom Rondeau wrote:
>>
> blks2.rational_resampler_ccf to resample to achieve closer sampling
>
>

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