On Fri, Mar 02, 2007 at 12:41:40AM -0800, seph 004 wrote: > I am only using 1 daughterboard. Sorry about the duc0 = 0 > inclusion. It's something I neglected to remove when I was editing > the original file. I don't think it should have any effect on what I > am seeing though. I set the duc frequency to 0 because I wanted to > transmit at baseband. I've already built the signal I want in the > gr.vector, I just want the daughterboard to pass it as is. I've > managed to do that with usrp_siggen.py. By setting the -f option to > 0 and the -w option to some frequency, I get a waveform of the -w > frequency at the daughterboard output. I'm pretty sure (0, 0) is > TXA, and (1, 0) is TXB. My waveform does appear at the TXB output > when I run the script. The problem is the pulse duration I'm seeing > is much shorter (about 1/10) than what I expect. > > Regards > Lance
Unless the total number of samples comes out to a multiple of 128, some will left in the host buffer and not transmitted across the USB. Try padding your vsource data with zeros to a multiple of 128. Eric > > ----- Original Message ---- > From: David Scaperoth <[EMAIL PROTECTED]> > To: seph 004 <[EMAIL PROTECTED]> > Cc: discuss-gnuradio@gnu.org > Sent: Thursday, March 1, 2007 7:15:36 PM > Subject: Re: [Discuss-gnuradio] The shortest pulse length > > > > > On 3/1/07, seph 004 <[EMAIL PROTECTED]> wrote: > > > > This is what I did: > > def build_graph (): > nchan = 1 > interp = 512 > duc0 = 0 > duc1 = 0 > fs = 250e3 #2nd sample rate > between usb and dac > > max_dev = 32e3 #1st sample rate divided by 4 > (1st = 2nd sample rate) > gain = 16e3 > k = 2 * math.pi * max_dev / fs > vec1 = Numeric.arange (0.624, 0.656, 0.0000128) > > vsource = gr.vector_source_f(vec1, False) > fmmod = gr.frequency_modulator_fc (k) > amp = gr.multiply_const_cc(gain) > > fg = gr.flow_graph () > > u = usrp.sink_c (0, interp, nchan) > > tx_subdev_spec = (1, 0) #usrp.pick_tx_subdevice(u) > m = usrp.determine_tx_mux_value(u, tx_subdev_spec) > u.set_mux(m) > subdev = usrp.selected_subdev(u, tx_subdev_spec) > subdev.set_enable(True) > > > sample_rate = u.dac_freq () / interp > u.set_tx_freq (0, duc0) > u.set_tx_freq (1, duc1) _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio