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[Discuss-gnuradio] Problem in using connect(gr.file_source, usrp.sink_s)

From: Eliane Hook
Subject: [Discuss-gnuradio] Problem in using connect(gr.file_source, usrp.sink_s)
Date: Wed, 11 Jul 2007 12:23:08 -0700


I am a newbie with GNURADIO and USRP. I am trying to capture data that comes thru the USB cable from the USRP board and transmit it back to the USRP board. I was reading thru the email archives and I came across this:

To log data from the USRP: usrp.source_c -> gr.file_sink(complex)
To replay data to the USRP: gr.file_source(complex) -> usrp.sink_c

and some more information like use the usrp_rx_cfile.py to capture data from the USRP. I am facing a problem in implementing ' gr.file_source(complex) -> usrp.sink_c'.

output.dat in the code is the binary file that I got from running usrp_rx_cfile.py with option 's' and 'f'. I am using the usrp.source_s and usrp.sink_s instead of usrp.source_c and usrp.sink_c. The code implementing the above is:

class my_graph(gr.flow_graph):

    def __init__(self):

        usage="%prog: [options] output_filename"
        parser = OptionParser(option_class=eng_option, usage=usage)
        parser.add_option("-R", "--tx-subdev-spec", type="subdev", default=(0, 0),
                          help="select USRP Tx side A or B (default=A)")
        parser.add_option("-i", "--interp", type="intx", default=16,
                          help="set fgpa interpolation rate to INTERP [default=%default]")
        parser.add_option("-f", "--freq", type="eng_float", default=None,
                          help="set frequency to FREQ", metavar="FREQ")
        parser.add_option ("-g", "--gain", type="eng_float", default=None,
                          help="set gain in dB (default is midpoint)")
        (options, args) = parser.parse_args ()

        if options.freq is None:
            sys.stderr.write('You must specify the frequency with -f FREQ\n');
            raise SystemExit, 1

        # build the graph
        self.u = usrp.sink_s(interp_rate=options.interp)
        self.dst = gr.file_source(gr.sizeof_short, 'output.dat')
        self.connect(self.dst, self.u)

        dac_rate= self.u.dac_rate();

        if options.tx_subdev_spec is None:
            options.tx_subdev_spec = usrp.pick_tx_subdevice(self.u)
        self.u.set_mux(usrp.determine_tx_mux_value(self.u, options.tx_subdev_spec))

        # determine the daughterboard subdevice we're using
        self.subdev = usrp.selected_subdev(self.u, options.tx_subdev_spec)
        print "Using TX d'board %s" % (self.subdev.side_and_name(),)

        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


        r = self.u.tune(0, self.subdev, options.freq)
        if not r:
            sys.stderr.write('Failed to set frequency\n')
            raise SystemExit, 1

if __name__ == '__main__':
    except KeyboardInterrupt:

and when I run it, I see the following:
../python/usrp# ./txIQ.py -f 2.4G
Using TX d'board A: Flex 2400 Tx MIMO B

The script runs for a second or two and stops immediately.

The email archives are very useful but still I am not able to implement what I want. Looking for some help. I really appreciate any help and thanks for the email responses in the archive.
-- Eliane

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