Thank you for all Eric. At now I'm editing the diagram (there are some block which names are in Portuguese).
I understood all when I connected the usrp(basicTX) to the spectrum analyzer(SA). I verified that when I sweep the frequency (f_LO on diagram), with f_signal(baseband)=0 Hz, I saw on SA 4 tones, one at f_LO , one at 128MHz - f_LO, one at 128MHz + f_LO and other at 200 MHz (I'm not sure about the last one). According to usrp_standard.cc the f_LO max is 44 MHz. If you put tune(target_freq=44e6) without a signal, you will see at least 3 tones: 1st @ 44MHz 2nd @ 128MHz - 44 MHz = 84 MHz 3rd @ 128 MHz + 44 MHz = 172 MHz If you send a signal, it will be upconverted in those 3 frequencies. Then, to tx something using a basicTX d'board you will need a RF filter after it. Soon I will send the corrected diagram, with the maximum allowable rates and frequencies. Regards, Ronaldo 2009/1/21 Eric Blossom <e...@comsec.com>: > On Mon, Jan 19, 2009 at 09:02:18AM -0200, Ronaldo Nunez wrote: >> Hello GnuRadio community, >> >> I made a transmission path diagram to try to understand how USRP works. >> I'm not sure if it's right, if somebody can correct it, it will be great! :D >> >> To debug the diagram I used these parameters, but I didn't get the >> right output (using USRP v1 and BasicTX d'board). >> >> ## Defined by user## >> f_signal = 4 MHz >> usb_rate (signal sample rate) = 2 * f_signal = 8 MHz >> L1 = 4 >> f_LO = 5 MHz >> >> ## Defined by Software (automatic) ## >> inter_sample_rate = usb_rate * L1 = 32MS/s >> f1=? >> f3=? >> >> ## Obtained inside AD9862 >> f2=? >> f4=? >> >> expected f4 = f_LO +/- f_signal = 5 MHz + 4 MHz = 9 MHz >> = 5 MHz - 4 MHz = 1 MHz >> ##Diagram## >> http://img164.imageshack.us/img164/4476/diageralfinalenusjm4.png >> > > Ronaldo, > > These (and your previous questions) are all good. > Have you tried printing out the result from: > > r = u.tune(...) > > print "r.baseband_freq", r.baseband_freq > print "r.dxc_freq", r.dxc_freq > print "r.residual_freq", r.residual_freq > print "r.inverted", r.inverted > > > The USB rate in complex samples/s is 128e6 / interp_rate > > Eric > -- __________________________________ Ronaldo A. Viera Nunez Acadêmico/Engenharia Elétrica Universidade Federal de Santa Maria Santa Maria - RS - Brasil _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
