On Wed, 2010-04-28 at 11:23 -0700, Johnathan Corgan wrote: > On Tue, Apr 27, 2010 at 21:19, John Andrews <gnu.f...@gmail.com> wrote: > > > If I want to transmit a signal which is DSSS spread using BPSK. Is it > > correct for me to first digitally spread the incoming data bits and then > > apply BPSK before sending it to the USRP or should I first convert the > > signal to BPSK and then multiply the output of the BPSK modulator with the > > PN sequence although I don't know how to do it. > > Technically, these are equivalent. However, it is easier and uses > less CPU to XOR your data sequence with your PN code, then send it to > the modulator. I think there is a difference, if you use a root raised cosine filter, set for your datarate and roll-off factor.
I think the correct version should then be: BPSKmod -> RRCfilter -> DSSS Martin > > Johnathan > > > _______________________________________________ > Discuss-gnuradio mailing list > Discuss-gnuradio@gnu.org > http://lists.gnu.org/mailman/listinfo/discuss-gnuradio > _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
