On Tue, Feb 15, 2011 at 11:31 AM, Daniel Dekst <dolk...@yahoo.com.cn> wrote:
> Hi, All, > > I'm using USRP1 with XCVR2450 daughterboard. > I transmit packets with OFDM modulation as in benchmark_ofdm_tx.py. > Using usrp_fft.py I detect the wave form as > http://www.cse.msu.edu/~huangpe3/music/usrp_fft.png > > The two edges are attenuated a lot and there is a spike in the middle (DC > offset?) > What are the reasons for them and can I address them by updating firmware > or something else to get better waveforms as those obtained from USRP2? > Yes, you will see a DC offset, but the rest of that looks wrong. You are probably sending too wide of a signal, which is getting hit by the half-band filters. What is the command-line you are using to set the interpolation rate and number of subcarriers? Tom > Changing the inerpolation rate changes the (frequency) bandwidth. > I know that higher data rate results in wider bandwidth. > But here the output rate is fixed by DAC 128 MS/s. Why the bandwidth is > changing in accordance with the interpolation rate? > > Thanks a lot for helping me out! > > Regards, > Pei > > ------------------------------ > Now that's room service! Choose from over 150,000 hotels > in 45,000 destinations on Yahoo! > Travel<http://travel.yahoo.com/hotelsearchpage;_ylc=X3oDMTFtaTIzNXVjBF9TAzk3NDA3NTg5BF9zAzI3MTk0ODEEcG9zAzIEc2VjA21haWx0YWdsaW5lBHNsawNxMS0wNw-->to > find your fit. > > _______________________________________________ > Discuss-gnuradio mailing list > Discuss-gnuradio@gnu.org > http://lists.gnu.org/mailman/listinfo/discuss-gnuradio > >
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