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#!/usr/bin/env python
import sys
import math
from gnuradio import gr, gru, audio, eng_notation, blks2, optfir
from gnuradio import uhd
from gnuradio.eng_option import eng_option
from optparse import OptionParser
# Load it locally or from the module
try:
import cqpsk
except:
from tetra_demod import cqpsk
# accepts an input file in complex format
# applies frequency translation, resampling (interpolation/decimation)
class my_top_block(gr.top_block):
def __init__(self, options):
gr.top_block.__init__(self)
# Create a UHD source
self._u = uhd.usrp_source(
device_addr=options.args,
io_type=uhd.io_type.COMPLEX_FLOAT32,
num_channels=1)
# Set the subdevice spec
if(options.spec):
self._u.set_subdev_spec(options.spec, 0)
# Set the antenna
if(options.antenna):
self._u.set_antenna(options.antenna, 0)
# Pick the lowest possible value for the input rate
supported_rates = self._u.get_samp_rates()
self._u.set_samp_rate(supported_rates.start())
sample_rate = self._u.get_samp_rate()
symbol_rate = 18000
sps = 2
# output rate will be 36,000
ntaps = 11 * sps
new_sample_rate = symbol_rate * sps
# Set receive daughterboard gain
if options.gain is None:
g = self._u.get_gain_range()
options.gain = float(g.stop()+g.start())/2
print "Using mid-point gain of", options.gain, "(", g.start(), "-", g.stop(), ")"
self._u.set_gain(options.gain)
# Set frequency (tune request takes lo_offset)
if(options.lo_offset is not None):
treq = uhd.tune_request(options.freq, options.lo_offset)
else:
treq = uhd.tune_request(options.freq)
tr = self._u.set_center_freq(treq)
if tr == None:
sys.stderr.write('Failed to set center frequency\n')
raise SystemExit, 1
channel_taps = gr.firdes.low_pass(1.0, sample_rate, options.low_pass, options.low_pass * 0.1, gr.firdes.WIN_HANN)
FILTER = gr.freq_xlating_fir_filter_ccf(1, channel_taps, options.calibration, sample_rate)
sys.stderr.write("sample rate: %d\n" %(sample_rate))
DEMOD = cqpsk.cqpsk_demod( samples_per_symbol = sps,
excess_bw=0.35,
costas_alpha=0.03,
gain_mu=0.05,
mu=0.05,
omega_relative_limit=0.05,
log=options.log,
verbose=options.verbose)
OUT = gr.file_sink(gr.sizeof_float, options.output_file)
r = float(sample_rate) / float(new_sample_rate)
INTERPOLATOR = gr.fractional_interpolator_cc(0, r)
self.connect(self._u, FILTER, INTERPOLATOR, DEMOD, OUT)
def get_options():
parser = OptionParser(option_class=eng_option)
# usrp related settings
parser.add_option("-a", "--args", type="string", default="",
help="UHD device address args, [default=%default]")
parser.add_option("", "--spec", type="string", default=None,
help="Subdevice of UHD device where appropriate")
parser.add_option("-A", "--antenna", type="string", default=None,
help="select Rx Antenna where appropriate")
parser.add_option("-f", "--freq", type="eng_float", default=None,
help="set frequency to FREQ", metavar="FREQ")
parser.add_option("-g", "--gain", type="eng_float", default=None,
help="set gain in dB (default is midpoint)")
parser.add_option("", "--lo-offset", type="eng_float", default=None,
help="set daughterboard LO offset to OFFSET [default=hw default]")
# demodulator related settings
parser.add_option("-c", "--calibration", type="int", default=0, help="freq offset")
parser.add_option("-l", "--log", action="store_true", default=False, help="dump debug .dat files")
parser.add_option("-L", "--low-pass", type="eng_float", default=25e3, help="low pass cut-off", metavar="Hz")
parser.add_option("-o", "--output-file", type="string", default="out.float", help="specify the bit output file")
parser.add_option("-v", "--verbose", action="store_true", default=False, help="dump demodulation data")
(options, args) = parser.parse_args()
if len(args) != 0:
parser.print_help()
raise SystemExit, 1
if options.freq is None:
parser.print_help()
sys.stderr.write('You must specify the frequency with -f FREQ\n');
raise SystemExit, 1
return (options)
if __name__ == "__main__":
(options) = get_options()
tb = my_top_block(options)
try:
tb.run()
except KeyboardInterrupt:
tb.stop()
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