1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
|
#!/usr/bin/env python
import sys
import math
from gnuradio import gr, gru, audio, eng_notation, blocks, filter
from gnuradio import audio
from gnuradio.eng_option import eng_option
from gnuradio.wxgui import stdgui2, fftsink2
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(stdgui2.std_top_block):
def __init__(self, frame, panel, vbox, argv):
stdgui2.std_top_block.__init__(self, frame, panel, vbox, argv)
self.frame = frame
self.panel = panel
options = get_options()
sample_rate = int(options.sample_rate)
self.asrc = audio.source(sample_rate, options.audio_device, True)
self.f2c = blocks.float_to_complex(1)
self.connect((self.asrc, 1), (self.f2c, 1))
self.connect((self.asrc, 0), (self.f2c, 0))
symbol_rate = 18000
sps = 2
# output rate will be 36,000
ntaps = 11 * sps
new_sample_rate = symbol_rate * sps
channel_taps = filter.firdes.low_pass(1.0, sample_rate, options.low_pass, options.low_pass * 0.1, filter.firdes.WIN_HANN)
FILTER = filter.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 = blocks.file_sink(gr.sizeof_float, options.output_file)
r = float(sample_rate) / float(new_sample_rate)
INTERPOLATOR = filter.fractional_interpolator_cc(0, r)
self.connect(self.f2c, FILTER, INTERPOLATOR, DEMOD, OUT)
self.scope = fftsink2.fft_sink_c(panel, fft_size=512,
sample_rate=sample_rate,
ref_scale=2.0,
ref_level=-30, y_divs=10,
fft_rate=10,
average=True,
avg_alpha=0.2)
self.connect(self.f2c, self.scope)
def get_options():
parser = OptionParser(option_class=eng_option)
parser.add_option("-r", "--sample-rate", type="eng_float", default=96000,
help="set sample rate to RATE (96000)")
parser.add_option("-D", "--audio-device", type="string", default="",
help="pcm input device name. E.g., hw:0,0 or /dev/dsp")
# 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
return (options)
if __name__ == "__main__":
app = stdgui2.stdapp(my_top_block, "OsmoTETRA FCDP", nstatus=1)
app.MainLoop()
|
