GMSK demod


#1

hi,
I am trying to demodulate GSM signals and captured some live GSM
data
using rfx900 on usrp. After running my code i encountered these
following
errors:

-gohar@ubuntu:~$ python ‘/home/gohar/Desktop/gsm.py’

gr_fir_ccf: using SSE
Traceback (most recent call last):
File line 90, in my_top_block().run()
File line 81, in init omega_relative_limit = 0)
TypeError: init() got multiple values for keyword argument ‘gain_mu’

The first one is regarding the FIR filter which i am using , i dont
know
the reason for this error " gr_fir_ccf: using SSE " , as in other
codes
it has been used in the same way as i did: the same is also the case
for my_top_block().run() and gmsk.demod() . The python code is as
fellows:

from gnuradio import gr, usrp, db_dbs_rx, blks2
from gnuradio import audio
from gnuradio.eng_option import eng_option
from optparse import OptionParser
from gnuradio.blks2impl import gmsk
from usrpm import usrp_dbid
import sys

constant

gsm_rate = 1625000.0 / 6.0

script constant

decim = 112
gain = 10

bts channel

c0 = 900.4e6

class my_top_block(gr.top_block):

def __init__(self):
            gr.top_block.__init__(self)
     u = usrp.source_c(decim_rate = decim)
            s = usrp.pick_subdev(u, (usrp_dbid.TV_RX,
                            usrp_dbid.TV_RX_REV_2,

usrp_dbid.TV_RX_REV_3,
usrp_dbid.BASIC_RX))
u.set_mux(usrp.determine_rx_mux_value(u, s))
subdev = usrp.selected_subdev(u, s)

            if subdev.dbid() is None:

raise Exception(‘dbs daughterboard yyy 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 )

xcf = 150e3
xtw = 50e3
xt = gr.firdes.low_pass(1.0, sps, xcf, xtw,
gr.firdes.WIN_HAMMING)
xf = gr.fir_filter_ccf(1, xt)

gd = gmsk.gmsk_demod(self, sps / gsm_rate, gain_mu = 0.01,
omega_relative_limit = 0.05)
g = gr.file_sink(gr.sizeof_gr_complex,data)
self.connect(u, xf, gd,g)

if name == ‘main’:
try:
my_top_block().run()
except KeyboardInterrupt:
pass
#####################################################

I will be very grateful if anyone can give me some advice to solve these
problems.

Thanks.