It's very likely that your on-disk sample format isn't what you've declared to Gnu Radio, and it's seeing some garbage numbers.
Is it possible that it's stored as 16-bit I 16-bit Q in the file? If so, you'll need to convert it before any of your complex-float blocks do anything with it. On Tue, 14 Feb 2012 12:02:34 -0800, emilio gonzalez wrote: > hello! > > i'm a new user embarking on some exploration to evaluate GNUradio and > the USRP platform for some multichannel radio monitoring. i am starting > with sample file processing before buying any hardware, as CPU usage is > my chief concern. > > my problem is with using a large sample file captured from the FM > broadcast-band: i can't get it to work with the simplest of graphs in > GRC. i was able to use Sharlene Katz's handy GRC tutorials to get her > AM sample file running through an FFT scope and demodulated to audio, so > i know my GNUradio install is working. however, running my WFM sample > file results in no activity on the FFT scope, and i get errors when > mousing over the FFT window. > > the sample file was described to me as 32-bit complex IQ baseband, > 98.0MHz center, 25Msps, gain 30 from an N200r4 + WBX. to try a very > simple graph, i loaded it in to the GRC like this: > [ File Source (complex) ] > -> [ Throttle (complex, 25M) ] > -> [ FFT Sink (complex, 25M rate, baseband 98M) ] > > running this graph results in an FFT scope with no activity; cutting > the sample rates to 250k has no effect. if i mouse over the FFT window > i get this error: > **** > Traceback (most recent call last): > File > "/opt/local/lib/python2.6/site-packages/gnuradio/wxgui/plotter/plotter_base.py", > line 187, in _on_paint > for fcn in self._draw_fcns: fcn[1]() > File > "/opt/local/lib/python2.6/site-packages/gnuradio/wxgui/plotter/plotter_base.py", > line 59, in draw > self._draw() > File > "/opt/local/lib/python2.6/site-packages/gnuradio/wxgui/plotter/grid_plotter_base.py", > line 395, in _draw_point_label > label_str = self._populate_point_label(x_val, y_val) > File > "/opt/local/lib/python2.6/site-packages/gnuradio/wxgui/plotter/channel_plotter.py", > line 150, in _populate_point_label > label_str += 'n%s: %s'%(channel, common.eng_format(y_value, > self.y_units)) > File > "/opt/local/lib/python2.6/site-packages/gnuradio/wxgui/plotter/common.py", > line 82, in eng_format > coeff, exp, prefix = get_si_components(num) > File > "/opt/local/lib/python2.6/site-packages/gnuradio/wxgui/plotter/common.py", > line 48, in get_si_components > exp = get_exp(num) > File > "/opt/local/lib/python2.6/site-packages/gnuradio/wxgui/plotter/common.py", > line 37, in get_exp > return int(math.floor(math.log10(abs(num)))) > ValueError: cannot convert float NaN to integer > **** > > relevant info: GNUradio 3.3.0, Python 2.6, Mac OS 10.7.3, MacPorts > install. sample data is stored on an internal hard drive. > > this seems like a pretty simple task, so there's either something > simple i'm missing or there's a bug or misconfiguration in my install. > any help would be appreciated - i've got a lot to figure out with this > file, but i can't seem to get past this step. > > thank you, > - emilio gonzalez > KI6NVO > > _______________________________________________ > Discuss-gnuradio mailing list > Discuss-gnuradio@gnu.org [1] > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio [2] Links: ------ [1] mailto:Discuss-gnuradio@gnu.org [2] https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
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