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
|
#!/usr/bin/env python
# $Id: gssm_stats.py,v 1.2 2007-07-07 16:31:44 jl Exp $
from gnuradio import gr, usrp, db_dbs_rx, blks
from gnuradio.blksimpl import gmsk
import usrp_dbid
import gssm
import sys
import time
import thread
# constant
gsm_rate = 1625000.0 / 6.0
# script constant
decim = 112
gain = 32
# bts channel
c0 = 874e6
# experimental constant
default_usrp_offset = 4e3
# filter constants
xcf = 150e3
xtw = 50e3
def display_stats(gs):
while 1:
print "%d:\t%d:%d" % \
(gs.d_found_fc_count, gs.d_valid_s, gs.d_invalid_s)
time.sleep(1)
class gssm_flow_graph(gr.flow_graph):
def __init__(self, usrp_offset):
gr.flow_graph.__init__(self)
print "decim = %d, gain = %d, offset = %.2f" % \
(decim, gain, usrp_offset)
print "filter center %.2f, filter width %.2f" % \
(xcf, xtw)
u = usrp.source_c(decim_rate = decim)
s = usrp.pick_subdev(u, (usrp_dbid.DBS_RX,))
u.set_mux(usrp.determine_rx_mux_value(u, s))
subdev = usrp.selected_subdev(u, s)
if subdev.dbid() != usrp_dbid.DBS_RX:
raise Exception('dbs daughterboard not detected!')
subdev.set_gain(gain)
sps = u.adc_freq() / u.decim_rate()
if sps < 2 * gsm_rate:
raise Exception('sample rate too low')
u.tune(0, subdev, c0 + usrp_offset)
xt = gr.firdes.low_pass(1.0, sps, xcf, xtw,
gr.firdes.WIN_HAMMING)
xf = gr.fir_filter_ccf(1, xt)
self.gs = gs = gssm.sink(sps)
self.connect(u, xf, gs)
def main():
if len(sys.argv) == 2:
uo = float(sys.argv[1])
else:
uo = default_usrp_offset
g = gssm_flow_graph(uo)
# thread.start_new_thread(display_stats, (g.gs,))
# g.run()
g.start()
time.sleep(10.0)
g.stop()
g.gs.stats()
if __name__ == '__main__':
main()
|
