Re: [Discuss-gnuradio] gr_remez error when running "usrp2_wfm_rcv.py" example

[Tom Rondeau]

On Fri, Sep 17, 2010 at 2:58 AM, Jorge Miguel <address@hidden> wrote:
> 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.
>
> address@hidden:/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 <module>
>     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


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