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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 usrp
from gnuradio.eng_option import eng_option
from optparse import OptionParser
try:
import cqpsk
except:
from tetra_demod import cqpsk
# applies frequency translation, resampling (interpolation/decimation) and cqpsk demodulation
class my_top_block(gr.top_block):
def __init__(self, options):
gr.top_block.__init__(self)
fusb_block_size = gr.prefs().get_long('fusb', 'block_size', 4096)
fusb_nblocks = gr.prefs().get_long('fusb', 'nblocks', 16)
self._u = usrp.source_c(decim_rate=options.decim, fusb_block_size=fusb_block_size, fusb_nblocks=fusb_nblocks)
# master clock
if options.fpga_freq is not None:
self._u.set_fpga_master_clock_freq(long(options.fpga_freq))
# default subdev if use didn't pick one
if options.rx_subdev_spec is None:
if u.db(0, 0).dbid() >= 0:
options.rx_subdev_spec = (0, 0)
elif u.db(1, 0).dbid() >= 0:
options.rx_subdev_spec = (1, 0)
else:
options.rx_subdev_spec = (0, 0)
# configure usrp mux
self._u.set_mux(usrp.determine_rx_mux_value(self._u, options.rx_subdev_spec))
# determine the daughterboard subdevice
self.subdev = usrp.selected_subdev(self._u, options.rx_subdev_spec)
# select antenna
if options.antenna is not None:
print "Selecting antenna %s" % (options.antenna,)
self.subdev.select_rx_antenna(options.antenna)
# set initial values
if options.gain is None:
# if no gain was specified, use the mid-point in dB
g = self.subdev.gain_range()
options.gain = float(g[0]+g[1])/2
r = self._u.tune(0, self.subdev, options.freq)
self.subdev.set_gain(options.gain)
#sample_rate = options.fpga_clock/options.decim
sample_rate = self._u.adc_freq() / self._u.decim_rate()
symbol_rate = 18000
sps = 2
# output rate will be 36,000
ntaps = 11 * sps
new_sample_rate = symbol_rate * sps
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("-d", "--decim", type="int", default=250,
help="Set USRP decimation rate to DECIM [default=%default]")
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("-R", "--rx-subdev-spec", type="subdev", default=None,
help="Select USRP Rx side A or B (default=first one with a daughterboard)")
parser.add_option("-A", "--antenna", default=None,
help="select Rx Antenna")
parser.add_option("-F", "--fpga-freq", type="eng_float", default=None,
help="set USRP reference clock frequency to FPGA_FREQ", metavar="FPGA_FREQ")
# 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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