Gr_remez error when running "usrp2_wfm_rcv.py" example

GNU Radio
1

After running the USRP2 GNU Radio example “usrp2_wfm_rcv.py” I got an
error
which I cannot find the solution in internet, any ideas?
Many thanks in advance.
Jorge.

user@user:/usr/share/gnuradio/examples/usrp2$ ./usrp2_wfm_rcv.py
Using RX d’board 0x0001
gr_remez: band edges must be nondecreasing
Traceback (most recent call last):
File “./usrp2_wfm_rcv.py”, line 284, in
app = stdgui2.stdapp (wfm_rx_block, “USRP2 WFM RX”)
File “/usr/lib/python2.6/dist-packages/gnuradio/wxgui/stdgui2.py”,
line
36, in init
wx.App.init (self, redirect=False)
File
“/usr/lib/python2.6/dist-packages/wx-2.8-gtk2-unicode/wx/_core.py”,
line 7978, in init
self._BootstrapApp()
File
“/usr/lib/python2.6/dist-packages/wx-2.8-gtk2-unicode/wx/_core.py”,
line 7552, in _BootstrapApp
return core.PyApp__BootstrapApp(*args, **kwargs)
File “/usr/lib/python2.6/dist-packages/gnuradio/wxgui/stdgui2.py”,
line
39, in OnInit
frame = stdframe (self.top_block_maker, self.title, self._nstatus)
File “/usr/lib/python2.6/dist-packages/gnuradio/wxgui/stdgui2.py”,
line
60, in init
self.panel = stdpanel (self, self, top_block_maker)
File “/usr/lib/python2.6/dist-packages/gnuradio/wxgui/stdgui2.py”,
line
81, in init
self.top_block = top_block_maker (frame, self, vbox, sys.argv)
File “./usrp2_wfm_rcv.py”, line 97, in init
60) # stopband attenuation
File “/usr/lib/python2.6/dist-packages/gnuradio/optfir.py”, line 44,
in
low_pass
taps = gr.remez (n + nextra_taps, fo, ao, w, “bandpass”)
File
“/usr/lib/python2.6/dist-packages/gnuradio/gr/gnuradio_swig_py_general.py”,
line 352, in remez
return _gnuradio_swig_py_general.remez(*args, **kwargs)
RuntimeError: gr_remez: band edges must be nondecreasing

2

On Fri, Sep 17, 2010 at 2:58 AM, Jorge M. [email protected] wrote:

app = stdgui2.stdapp (wfm_rx_block, "USRP2 WFM RX")

39, in OnInit
low_pass
taps = gr.remez (n + nextra_taps, fo, ao, w, “bandpass”)
File
“/usr/lib/python2.6/dist-packages/gnuradio/gr/gnuradio_swig_py_general.py”,
line 352, in remez
return _gnuradio_swig_py_general.remez(*args, **kwargs)
RuntimeError: gr_remez: band edges must be nondecreasing

That’s a very odd response. According to the code for
usrp2_wfm_rcv.py, the filter is defined (on line 95) as:

   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

Where usrp_rate = 320e3. That does not violate the filter parameters
(115 > 80). When I took this code out into a flowgraph I created
myself to test it, it runs fine. If you set 115e3 to, say, 70e3, then
you get that error message.

So unless the file has been altered, I don’t see why this error
message would be generated.

Tom