Hello to the list I am trying to build a simple SSB transmitter using GRC - GR-3.2.2. I use the 32Khz sampled audio source and bandpass it to reduce bandwidth to minimum. In order to match USRP usable interpolation, I have to set an interpolation by 10 to the bandpass, so that 32K * 10 * 400 = 128MSPS.
I've actually managed to get the RF signal out of the USRP, but it isn't really satisfactory. The 10-interpolated spectrum contains my baseband signal's spectral replicas spaced by 32kHz, as it always is the case when interpolate. My problem is that if I put a lowpass filter between the bandpass and USRP sink, working at 320kHz, the CPU cannot keep up and I get uUuUaOaO like raining. I use an AMD-3X Phenom with 3x2.3GHz cores and Ubuntu 9.04. Actually I see that 1 of the cores jumps to full 2.3G speed and gets stuck at 100% usage. >From the theory I understand that we should lowpass after interpolating. Is there any more efficient way to get rid of the spectral replicas, working at 320kSPS? Thanks in advance for any suggestion. Alberto Presentaci un amico! Invita i tuoi amici a scoprire i servizi Tiscali: per ogni amico che attiverà un servizio Tiscali, potrai avere 30 euro di sconto e lo stesso sconto di 30 euro verrà poi offerto al tuo amico. Scopri come! http://abbonati.tiscali.it/presentaci_un_amico/?WT.mc_id=01fw _______________________________________________ Discuss-gnuradio mailing list [email protected] http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
