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#!/usr/bin/env python
import sys
import math
from gnuradio import gr, gru, audio, eng_notation, blks2, optfir
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):
gr.top_block.__init__(self)
parser = OptionParser(option_class=eng_option)
parser.add_option("-c", "--calibration", type="eng_float", default=0, help="freq offset")
parser.add_option("-i", "--input-file", type="string", default="in.dat", help="specify the input file")
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.dat", help="specify the output file")
parser.add_option("-s", "--sample-rate", type="int", default=100000000/512, help="input sample rate")
parser.add_option("-v", "--verbose", action="store_true", default=False, help="dump demodulation data")
(options, args) = parser.parse_args()
sample_rate = options.sample_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))
IN = gr.file_source(gr.sizeof_gr_complex, options.input_file)
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(IN, FILTER, INTERPOLATOR, DEMOD, OUT)
if __name__ == "__main__":
try:
my_top_block().run()
except KeyboardInterrupt:
tb.stop()
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