On Wed, Oct 26, 2011 at 11:00 AM, Vanessa Gardellin < vanessa.gardel...@iit.cnr.it> wrote:
> Dear all, > > I am trying to use the alamouti code implemented by trondeau. > Studying the gr_ofdm_frame_acquisition I found several concepts that > are not clear to me: > Wow, this code is pretty old, and we never did finish it. I hope you get it working! I'd love to see the results. > 1) d_phase_count: what does it mean? > We have a look up table for various phase rotations to use in the calculations instead of recalculating them every time. This is the index into the LUT. > 2) coarse_freq_comp(int freq_delta, int count): which is the meaning > of this function? > If the frequency offset is larger than a subcarrier spacing, we want to correct for that. Once the number of subcarrier offset is found, we use this function to recenter it. The fine frequency correct has already been taken care of to center the signals to the center of a subcarrier. > 3) what "-M_TWOPI*freq_delta*d_cplen/d_fft_length" represents? > This is the integer number of subarriers (freq_delta) and the phase correction per subcarrier. > Thank you > > Vanessa > Tom > On Fri, Oct 21, 2011 at 1:39 PM, Vanessa Gardellin > <vanessa.gardel...@iit.cnr.it> wrote: > > Dear all, > > I am trying to configure a simple flow graph where I have 2 USRP N210 > > connected using a mimo cable. > > The ethernet is connected only to the device with IP 192.168.20.2. > > > > my python code is: > > > > self.uhd_usrp_source_0 = uhd.usrp_source( > > device_addr= "addr=192.168.20.2, addr=192.168.20.3", > > io_type=uhd.io_type.COMPLEX_FLOAT32, > > num_channels=2, > > ) > > > > _config = uhd.clock_config() > > _config.ref_source = uhd.clock_config.REF_MIMO > > _config.pps_source = uhd.clock_config.PPS_MIMO > > self.uhd_usrp_source_0.set_clock_config(_config) > > > > > > and my problem is that I can see the received led turned only on the > > 192.168.20.3 device. > > > > > > Moreover, it's not clear what channels are and how I should address > > the 2 devices. > > > > Thanks > > > > Vanessa > > > > > > -- > Vanessa GARDELLIN, Ph.D. > Researcher > Institute for Informatics and Telematics (IIT), > Italian National Research Council (CNR) > Via G. Moruzzi 1 > 56124 Pisa - ITALY > Phone: +390503153267 > Room: B65/c > E-mail: vanessa.gardel...@iit.cnr.it > WWW: http://www.iit.cnr.it/staff/vanessa.gardellin/ > Skype: gardellin.vanessa > > _______________________________________________ > Discuss-gnuradio mailing list > Discuss-gnuradio@gnu.org > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >
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