On Tue, Mar 10, 2009 at 4:13 PM, Peter Vizi <[email protected]> wrote: > List, > > We are implementing a packet-based system with gnuradio, and we > experience that the packets are not sent in one flush from the USRP. > > In our transmitter we are maintaining a data path and a control path, so > we exactly know where is the beginning of a packet and where is the end. > We use this method to pad the outgoing complex waveform to the multiple > of 128 samples, as it is required by the USRP (in a particular setup our > packet is 468 samples long, so it is padded to 512 samples). > > Image [1] shows the abs of the complex waveform that our transmitter > block produces, this is fed into the USRP sink (a copy of the ofdm > benchmark's USRP sink). Image [2] shows abs from the received signal > when the transmitter was operating. You can discover the preamble in the > received signal and similar things to the rest of the packet, but this > is not continuous. Interestingly there seems to be some parts from the > previous packet before the preamble. > > We tried to set the fusb_block_size of the USRP sink to 8, so this > buffer will hold a whole packet, but this did not help either. > > Any ideas would be greatly appreciated. > > Best, Peter. > > [1] http://nd.edu/~pvizi/transmitted.png > [2] http://nd.edu/~pvizi/onair.png
Please label your axes! I'm not sure what I'm looking at here. Also, from what I gather, you are doing a comparison, but you are using two different ranges in the x-axis. I am not at all clear what the problem you are having is from your explanation. Tom _______________________________________________ Discuss-gnuradio mailing list [email protected] http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
