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# Copyright 2008 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.
#
default_win_size = 1000
from gnuradio import gr
import gnuradio.gr.gr_threading as _threading
import numpy
#generate 1s counts array
_1s_counts = [sum([1&(i>>j) for j in range(8)]) for i in range(2**8)]
class input_watcher(_threading.Thread):
"""
Read samples from the message queue and hand them to the callback.
"""
def __init__(self, msgq, callback):
self._msgq = msgq
self._callback = callback
_threading.Thread.__init__(self)
self.setDaemon(1)
self.keep_running = True
self.start()
def run(self):
r = ''
while True:
msg = self._msgq.delete_head()
itemsize = int(msg.arg1())
nitems = int(msg.arg2())
s = r + msg.to_string()
i = (nitems-nitems%2)*itemsize
r = s[i:]
s = s[:i]
samples = numpy.fromstring(s, numpy.int8)
self._callback(samples)
class error_rate(gr.hier_block2):
"""
Sample the incoming data streams (byte) and calculate the bit or symbol error rate.
Write the running rate to the output data stream (float).
"""
def __init__(self, type='BER', win_size=default_win_size, bits_per_symbol=2):
"""
Error rate constructor.
@param type a string 'BER' or 'SER'
@param win_size the number of samples to calculate over
@param bits_per_symbol the number of information bits per symbol (BER only)
"""
#init
gr.hier_block2.__init__(
self, 'error_rate',
gr.io_signature(2, 2, gr.sizeof_char),
gr.io_signature(1, 1, gr.sizeof_float),
)
assert type in ('BER', 'SER')
self._max_samples = win_size
self._bits_per_symbol = bits_per_symbol
#setup message queue
msg_source = gr.message_source(gr.sizeof_float, 1)
self._msgq_source = msg_source.msgq()
msgq_sink = gr.msg_queue(2)
msg_sink = gr.message_sink(gr.sizeof_char, msgq_sink, False) #False -> blocking
inter = gr.interleave(gr.sizeof_char)
#start thread
self._num_errs = 0
self._err_index = 0
self._num_samps = 0
self._err_array = numpy.zeros(self._max_samples, numpy.int8)
if type == 'BER':
input_watcher(msgq_sink, self._handler_ber)
elif type == 'SER':
input_watcher(msgq_sink, self._handler_ser)
#connect
self.connect(msg_source, self)
self.connect((self, 0), (inter, 0))
self.connect((self, 1), (inter, 1))
self.connect(inter, msg_sink)
def _handler_ber(self, samples):
num = len(samples)/2
arr = numpy.zeros(num, numpy.float32)
for i in range(num):
old_err = self._err_array[self._err_index]
#record error
self._err_array[self._err_index] = _1s_counts[samples[i*2] ^ samples[i*2 + 1]]
self._num_errs = self._num_errs + self._err_array[self._err_index] - old_err
#increment index
self._err_index = (self._err_index + 1)%self._max_samples
self._num_samps = min(self._num_samps + 1, self._max_samples)
#write sample
arr[i] = float(self._num_errs)/float(self._num_samps*self._bits_per_symbol)
#write message
msg = gr.message_from_string(arr.tostring(), 0, gr.sizeof_float, num)
self._msgq_source.insert_tail(msg)
def _handler_ser(self, samples):
num = len(samples)/2
arr = numpy.zeros(num, numpy.float32)
for i in range(num):
old_err = self._err_array[self._err_index]
#record error
ref = samples[i*2]
res = samples[i*2 + 1]
if ref == res:
self._err_array[self._err_index] = 0
else:
self._err_array[self._err_index] = 1
#update number of errors
self._num_errs = self._num_errs + self._err_array[self._err_index] - old_err
#increment index
self._err_index = (self._err_index + 1)%self._max_samples
self._num_samps = min(self._num_samps + 1, self._max_samples)
#write sample
arr[i] = float(self._num_errs)/float(self._num_samps)
#write message
msg = gr.message_from_string(arr.tostring(), 0, gr.sizeof_float, num)
self._msgq_source.insert_tail(msg)
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