#!/usr/bin/env python
#
# Copyright 2012,2013 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.
#
import numpy
import random
from gnuradio import gr, gr_unittest, blocks, analog, channels
from gnuradio import digital
from gnuradio.digital.utils import tagged_streams
from gnuradio.digital.ofdm_txrx import ofdm_tx
class qa_ofdm_sync_sc_cfb (gr_unittest.TestCase):
def setUp (self):
self.tb = gr.top_block ()
def tearDown (self):
self.tb = None
def test_001_detect (self):
""" Send two bursts, with zeros in between, and check
they are both detected at the correct position and no
false alarms occur """
n_zeros = 15
fft_len = 32
cp_len = 4
sig_len = (fft_len + cp_len) * 10
sync_symbol = [(random.randint(0, 1)*2)-1 for x in range(fft_len/2)] * 2
tx_signal = [0,] * n_zeros + \
sync_symbol[-cp_len:] + \
sync_symbol + \
[(random.randint(0, 1)*2)-1 for x in range(sig_len)]
tx_signal = tx_signal * 2
add = blocks.add_cc()
sync = digital.ofdm_sync_sc_cfb(fft_len, cp_len)
sink_freq = blocks.vector_sink_f()
sink_detect = blocks.vector_sink_b()
self.tb.connect(blocks.vector_source_c(tx_signal), (add, 0))
self.tb.connect(analog.noise_source_c(analog.GR_GAUSSIAN, .01), (add, 1))
self.tb.connect(add, sync)
self.tb.connect((sync, 0), sink_freq)
self.tb.connect((sync, 1), sink_detect)
self.tb.run()
sig1_detect = sink_detect.data()[0:len(tx_signal)/2]
sig2_detect = sink_detect.data()[len(tx_signal)/2:]
self.assertTrue(abs(sig1_detect.index(1) - (n_zeros + fft_len + cp_len)) < cp_len)
self.assertTrue(abs(sig2_detect.index(1) - (n_zeros + fft_len + cp_len)) < cp_len)
self.assertEqual(numpy.sum(sig1_detect), 1)
self.assertEqual(numpy.sum(sig2_detect), 1)
def test_002_freq (self):
""" Add a fine frequency offset and see if that gets detected properly """
fft_len = 32
cp_len = 4
# This frequency offset is normalized to rads, i.e. \pi == f_s/2
max_freq_offset = 2*numpy.pi/fft_len # Otherwise, it's coarse
freq_offset = ((2 * random.random()) - 1) * max_freq_offset
sig_len = (fft_len + cp_len) * 10
sync_symbol = [(random.randint(0, 1)*2)-1 for x in range(fft_len/2)] * 2
tx_signal = sync_symbol[-cp_len:] + \
sync_symbol + \
[(random.randint(0, 1)*2)-1 for x in range(sig_len)]
sync = digital.ofdm_sync_sc_cfb(fft_len, cp_len, True)
sink_freq = blocks.vector_sink_f()
sink_detect = blocks.vector_sink_b()
channel = channels.channel_model(0.005, freq_offset / 2.0 / numpy.pi)
self.tb.connect(blocks.vector_source_c(tx_signal), channel, sync)
self.tb.connect((sync, 0), sink_freq)
self.tb.connect((sync, 1), sink_detect)
self.tb.run()
phi_hat = sink_freq.data()[sink_detect.data().index(1)]
est_freq_offset = 2 * phi_hat / fft_len
self.assertAlmostEqual(est_freq_offset, freq_offset, places=2)
def test_003_multiburst (self):
""" Send several bursts, see if the number of detects is correct.
Burst lengths and content are random.
"""
n_bursts = 42
fft_len = 32
cp_len = 4
tx_signal = []
for i in xrange(n_bursts):
sync_symbol = [(random.randint(0, 1)*2)-1 for x in range(fft_len/2)] * 2
tx_signal += [0,] * random.randint(0, 2*fft_len) + \
sync_symbol[-cp_len:] + \
sync_symbol + \
[(random.randint(0, 1)*2)-1 for x in range(fft_len * random.randint(5,23))]
add = blocks.add_cc()
sync = digital.ofdm_sync_sc_cfb(fft_len, cp_len)
sink_freq = blocks.vector_sink_f()
sink_detect = blocks.vector_sink_b()
channel = channels.channel_model(0.005)
self.tb.connect(blocks.vector_source_c(tx_signal), channel, sync)
self.tb.connect((sync, 0), sink_freq)
self.tb.connect((sync, 1), sink_detect)
self.tb.run()
n_bursts_detected = numpy.sum(sink_detect.data())
# We allow for one false alarm or missed burst
self.assertTrue(abs(n_bursts_detected - n_bursts) <= 1,
msg="""Because of statistics, it is possible (though unlikely)
that the number of detected bursts differs slightly. If the number of detects is
off by one or two, run the test again and see what happen.
Detection error was: %d """ % (numpy.sum(sink_detect.data()) - n_bursts)
)
def test_004_ofdm_packets (self):
"""
Send several bursts using ofdm_tx, see if the number of detects is correct.
Burst lengths and content are random.
"""
n_bursts = 42
fft_len = 64
cp_len = 16
# Here, coarse freq offset is allowed
max_freq_offset = 2*numpy.pi/fft_len * 4
freq_offset = ((2 * random.random()) - 1) * max_freq_offset
tx_signal = []
packets = []
tagname = "packet_length"
min_packet_length = 10
max_packet_length = 50
sync_sequence = [random.randint(0, 1)*2-1 for x in range(fft_len/2)]
for i in xrange(n_bursts):
packet_length = random.randint(min_packet_length,
max_packet_length+1)
packet = [random.randint(0, 255) for i in range(packet_length)]
packets.append(packet)
data, tags = tagged_streams.packets_to_vectors(packets, tagname, vlen=1)
total_length = len(data)
src = blocks.vector_source_b(data, False, 1, tags)
mod = ofdm_tx(packet_length_tag_key=tagname)
sync = digital.ofdm_sync_sc_cfb(fft_len, cp_len)
sink_freq = blocks.vector_sink_f()
sink_detect = blocks.vector_sink_b()
noise_level = 0.005
channel = channels.channel_model(noise_level, freq_offset / 2 / numpy.pi)
self.tb.connect(src, mod, channel, sync, sink_freq)
self.tb.connect((sync, 1), sink_detect)
self.tb.run()
self.assertEqual(numpy.sum(sink_detect.data()), n_bursts)
if __name__ == '__main__':
gr_unittest.run(qa_ofdm_sync_sc_cfb, "qa_ofdm_sync_sc_cfb.xml")