Re: [Discuss-gnuradio] analysis_filterbank problem

[Eric Blossom]

On Wed, Jan 07, 2009 at 01:53:03PM +0200, Sebastiaan Heunis wrote:
> Hi
> 
> I looked at usrp_flex_band.py to see how blks2.analysis_filterbank is
> implemented.  The example runs on my PC.
> 
> I wrote a simple app where I want to decimate by 16 in the FPGA (no
> HBF).  So I have samples coming in at 4Msps.  I then want to send this
> stream to a 20 channel channeliser, resulting in output streams of
> 200ksps each.  I want to test this by connecting an FM demodulator and
> see if I can channelise a part of the FM band.  Here is some of my
> code.
> 
> self.u = usrp.source_c(decim_rate=16,fpga_filename="std_2rx_0tx.rbf")
> 
> if options.rx_subdev_spec is None:
>       options.rx_subdev_spec = pick_subdevice(self.u)
>               
> self.subdev = usrp.selected_subdev(self.u,options.rx_subdev_spec)
> self.u.set_mux(usrp.determine_rx_mux_value(self.u,options.rx_subdev_spec))
>               
> print "Using RX d'board %s" % (self.subdev.side_and_name(),)
> 
> self.set_freq(options.freq)
> 
> taps = []
> 
> f1 = open('fir_lowpass.txt','r')
> 
> for line in f1:
>       tap = float(line)
>       taps.append(tap)
> f1.close()
> 
> #taps = optfir.low_pass(1,usrp_rate,70e3,100e3,0.1,60)
> 
> pfb = blks2.analysis_filterbank(20,taps)
> 
> self.connect(self.u,pfb)
> 
> The application works until I try to connect the usrp source to the
> filterbank.  I get a Segmentation fault when I try to do this.  Does
> anyone know what might be wrong?
> 
> Thanks in advance.
> 
> Sebastiaan


Run gdb to find out where the segfault is occurring.
http://www.gnu.org/software/gnuradio/doc/howto-write-a-block.html#debugging


Are you sure you want the half-band disabled?  
You can run decim=16 with it on.  The pass band will be flatter.

Eric