I know that the best method for correlating a is to use the new GMSK
code. However, I am trying to understand the difference between the
run and start/stop/wait commands and also gain additional insight into
the simple_correlator function. When I try to run the below code using
the fg.run command it displays the appropriate sequence numbers. Once
it reaches the final packet, the program stops and seems to be waiting
for additional input. I suspect that this hang up is caused by the
simple_correlator function, but I am not really sure of the details of
why. If I replace the fg.run command with the combination of fg.start
and fg.stop, the program works fine. However, I would prefer not to
have to hit enter once the program finishes executing. Why does
fg.start/stop work but fg.run not work? Also, in the check_lfsr
function, what is the significance of runlength value?
Thanks,
Mike
#!/usr/bin/env python
from gnuradio import gr
from gnuradio.eng_option import eng_option
from optparse import OptionParser
import math
from gnuradio.wxgui import scopesink
from gnuradio.wxgui import stdgui, fftsink
import wx
from gnuradio import howto
from gnuradio import usrp
def open_pipelines (filename, repeat):
payload_size = 1024 # in bytes
data_rate = 100e3
sw_interp = 8
fs = sw_interp * data_rate
fg = gr.flow_graph()
tx_max_deviation = 50e3 stream_length = 100*512 # in shorts
# ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
# Transmitter Pipeline
# ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
data_src = gr.lfsr_32k_source_s ()
src_head = gr.head (gr.sizeof_short, int (stream_length))
shorts_to_bytes = howto.shorts_to_bytes ()
framer = gr.simple_framer (payload_size)
bytes_to_syms = gr.bytes_to_syms ()
if 1:
interp_taps = gr.firdes.low_pass (sw_interp, # gain
fs, # sampling rate
data_rate / 2 * 1.2, # cutoff
data_rate/2 * 0.4, #
trans width
gr.firdes.WIN_HANN)
interp = gr.interp_fir_filter_fff (sw_interp, interp_taps)
k = 2 * math.pi * tx_max_deviation / fs
fmmod = gr.frequency_modulator_fc (k)
gain = gr.multiply_const_cc (16000)
fg.connect (data_src, src_head, shorts_to_bytes, framer,
bytes_to_syms, interp, fmmod, gain)
# ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
# Receiver Pipeline
# ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
filter_taps = gr.firdes.low_pass (1, # gain
fs, # sampling rate
data_rate / 2 * 1.1, # cutoff
data_rate, # trans width
gr.firdes.WIN_HANN)
filter = gr.fir_filter_ccf (1, filter_taps)
k = 1
fmdemod = gr.quadrature_demod_cf (k)
corr = gr.simple_correlator (payload_size)
bytes_to_shorts = howto.bytes_to_shorts ()
head = gr.head (gr.sizeof_short, stream_length)
check = gr.check_lfsr_32k_s ()
fg.connect (gain, filter, fmdemod, corr, bytes_to_shorts, head, check)
fg.run ()
ntotal = check.ntotal ()
nright = check.nright ()
runlength = check.runlength ()
print "ntotal =", ntotal
print "nright =", nright
print "nwrong =", ntotal-nright
print "runlength =", runlength
print "error rate =", (ntotal-nright)/(1.0*ntotal)
#
::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
# Main
#
::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
def main():
parser = OptionParser (option_class=eng_option)
parser.add_option ("-f", "--filename", type="string",
default="payload.txt",
help="read data from FILENAME")
parser.add_option ("-R", "--repeat", action="store_true", default=False)
(options, args) = parser.parse_args ()
open_pipelines (options.filename, options.repeat)
if __name__ == '__main__':
try:
main()
except KeyboardInterrupt:
pass
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