Report change of python script from 3.1.3 to 3.2

Friends,

I changed my GRBR (GNU Radio Beacon Receiver) python script
from version 3.1.3 to version 3.2. I report some small
findings from my experience.

(1) I am using “usrp.cal_dxc_freq” in my scirpt, but it is
missing in ver 3.2. I am sure it will be fixed in future.
I made a small replacement function as shown below. (See (4))

(2) “set_freq” method for a daughterboard changed its return.
Before, it was a tuple of (ok, baseband_freq), but now it is
a “freq_result_t” structure. “ok” and “baseband_freq”
are members of the structure.

(3) Members of classes changed a lot. More members
are clearly seen in version 3.2. One change was selection
of a daughter board. Before we had a “db[0][0]” or “db[1][0]”
type of member (value). Now it is method like db(0,0) or
db(1,0). Return is the same (handle to the daughter board).
Another finding is “_which” of a daughter board. This is now
changed to be a method “which()”. My understanding of this
“which()” is to show corresponding DDC number on the main board.
… Am I correct?

(4) Beacuse of change (1) and (2), GNU Radio example,
usrp_wfm_rcv2_nogui.py does not work. I modified the script
as shown below. Replace of calc_dxc_freq is included.
This works, but I have not yet tested with the real signal.
I hope someone can try.

Regards,

Mamoru Y.

=== usrp_wfm_rcv2_nogui.py modified for version 3.2 ===
#!/usr/bin/env python

Copyright 2005,2006,2007 Free Software Foundation, Inc.

This file is part of GNU Radio

GNU Radio is free software; you can redistribute it and/or modify

it under the terms of the GNU General Public License as published by

the Free Software Foundation; either version 3, or (at your option)

any later version.

GNU Radio is distributed in the hope that it will be useful,

but WITHOUT ANY WARRANTY; without even the implied warranty of

MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

GNU General Public License for more details.

You should have received a copy of the GNU General Public License

along with GNU Radio; see the file COPYING. If not, write to

the Free Software Foundation, Inc., 51 Franklin Street,

Boston, MA 02110-1301, USA.

from gnuradio import gr, gru, eng_notation, optfir
from gnuradio import audio
from gnuradio import usrp
from gnuradio import blks2
from gnuradio.eng_option import eng_option
from optparse import OptionParser
from usrpm import usrp_dbid
import sys
import math

def my_calc_dxc_freq(target_freq, baseband_freq, fs):
“”"
Add (hopefully) equivalent to calc_dxc_freq
that is missing at 3.2 as a private function.
“”"
dxc_temp = (target_freq - baseband_freq) % fs

if dxc_temp < fs/2.0:
    dxc_freq = - dxc_temp
    inverted = False
else:
    dxc_freq = fs - dxc_temp
    inverted = True

return (dxc_freq, inverted)

def pick_subdevice(u):
“”"
The user didn’t specify a subdevice on the command line.
Try for one of these, in order: TV_RX, BASIC_RX, whatever is on side
A.

@return a subdev_spec
"""
return usrp.pick_subdev(u, (usrp_dbid.TV_RX,
                            usrp_dbid.TV_RX_REV_2,
                            usrp_dbid.BASIC_RX))

class wfm_rx_block (gr.top_block):

def __init__(self):
    gr.top_block.__init__(self)

    parser=OptionParser(option_class=eng_option)
    parser.add_option("-R", "--rx-subdev-spec", type="subdev", 

default=None,
help=“select USRP Rx side A or B (default=A)”)
parser.add_option("", “–f1”, type=“eng_float”, default=100.7e6,
help=“set 1st station frequency to FREQ”,
metavar=“FREQ”)
parser.add_option("", “–f2”, type=“eng_float”, default=102.5e6,
help=“set 2nd station freq to FREQ”,
metavar=“FREQ”)
parser.add_option("-g", “–gain”, type=“eng_float”, default=40,
help=“set gain in dB (default is midpoint)”)
parser.add_option("-O", “–audio-output”, type=“string”,
default="",
help=“pcm device name. E.g., hw:0,0 or
surround51 or
/dev/dsp”)

    (options, args) = parser.parse_args()
    if len(args) != 0:
        parser.print_help()
        sys.exit(1)

    if abs(options.f1) < 1e6:
        options.f1 *= 1e6

    if abs(options.f2) < 1e6:
        options.f2 *= 1e6

    if abs(options.f1 - options.f2) > 5.5e6:
        print "Sorry, two stations must be within 5.5MHz of each 

other"
raise SystemExit

    f = (options.f1, options.f2)

    self.vol = .1
    self.state = "FREQ"

    # build graph

    self.u = usrp.source_c(0, nchan=2)          # usrp is data 

source

    adc_rate = self.u.adc_rate()                # 64 MS/s
    usrp_decim = 200
    self.u.set_decim_rate(usrp_decim)
    usrp_rate = adc_rate / usrp_decim           # 320 kS/s
    chanfilt_decim = 1
    demod_rate = usrp_rate / chanfilt_decim
    audio_decimation = 10
    audio_rate = demod_rate / audio_decimation  # 32 kHz


    if options.rx_subdev_spec is None:
        options.rx_subdev_spec = pick_subdevice(self.u)

    mv = usrp.determine_rx_mux_value(self.u, options.rx_subdev_spec)
    mv |= (mv << 8) & 0xff00   # both DDC inputs setup same way
    self.u.set_mux(mv)
    self.subdev = usrp.selected_subdev(self.u, 

options.rx_subdev_spec)
print “Using RX d’board %s” % (self.subdev.side_and_name(),)

    # deinterleave two channels from FPGA
    di = gr.deinterleave(gr.sizeof_gr_complex)

    # wire up the head of the chain
    self.connect(self.u, di)

    # sound card as final sink
    audio_sink = audio.sink(int(audio_rate), options.audio_output)

    # taps for channel filter
    chan_filt_coeffs = optfir.low_pass (1,           # gain
                                        usrp_rate,   # sampling rate
                                        80e3,        # passband 

cutoff
115e3, # stopband
cutoff
0.1, # passband
ripple
60) # stopband
attenuation
#print len(chan_filt_coeffs)

    mid_freq = (f[0] + f[1]) / 2
    # set front end PLL to middle frequency

ok, baseband_freq = self.subdev.set_freq(mid_freq)

Old-style until
version 3.1.3
f_result = self.subdev.set_freq(mid_freq) # New-style from
version 3.2
ok = f_result.ok
baseband_freq = f_result.baseband_freq

    for n in range(2):
        chan_filt = gr.fir_filter_ccf (chanfilt_decim, 

chan_filt_coeffs)
guts = blks2.wfm_rcv (demod_rate, audio_decimation)
volume_control = gr.multiply_const_ff(self.vol)
self.connect((di, n), chan_filt)
self.connect(chan_filt, guts, volume_control)
self.connect(volume_control, (audio_sink, n))

Modification as “calc_dxc_freq” is now missing at verstion 3.2

dxc_freq, inverted = usrp.calc_dxc_freq(f[n],

baseband_freq,

self.u.converter_rate())
dxc_freq, inverted = my_calc_dxc_freq(f[n], baseband_freq,
self.u.converter_rate())
self.u.set_rx_freq(n, dxc_freq)

    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


    # set initial values
    self.set_gain(options.gain)


def set_vol (self, vol):
    self.vol = vol
    self.volume_control.set_k(self.vol)


def set_gain(self, gain):
    self.subdev.set_gain(gain)

def __del__(self):

Avoid weak-reference error

del self.subdev

if name == ‘main’:
tb = wfm_rx_block()
try:
tb.run()
except KeyboardInterrupt:
pass


Mamoru Y.
Research Institute for Sustainable Humanosphere (RISH)
Kyoto University
[email protected]