Sorry if it sounds silly, but why one is supposed to get DC out of the DAC if Carrier Freq is set to zero?
What if one generates a 1Mhz QPSK in GNURadio ? Its not zero hertz, its baseband... Im puzzled... Angilberto. --- Matt Ettus <[EMAIL PROTECTED]> wrote: > On Sat, 2006-05-27 at 12:16 -0700, Thomas Schmid > wrote: > > Hi, > > > > I have a question about the basic RX/TX boards. > What should I see if I > > hook the basic TX board to an oscilloscope if I > send out a QPSK > > signal? Here is what I do: > > - I generate a QPSK signal in GnuRadio > > - I send the signal to a complex file source and > the signal looks right > > - I send the signal to the complex USRP source and > have a BasicTX on > > it. The outputs TXA and TXB are hooked up to a > oscilloscope on channel > > 1 and 2 respectively. > > > > Now, what should I see on the oscilloscope? Is it > the baseband signal? > > How does the I and Q phases get mixed together? > Does that depend on > > the mux values? Unfortunately I couldn't find a > good block diagram of > > the TX path on the wiki, i.e., the link to [A > system block diagram of > > the USRP receiver and transmitter path] on the > wiki page > > > "http://www.comsec.com/wiki?UniversalSoftwareRadioPeripheral"; > is dead. > > If you set the carrier frequency to 0 you will see > the I signal on the I > channel out and the Q signal on the Q channel out. > This will only be > useful with the LFTX board since the BasicTX will > block DC. > > If you set the carrier frequency to something other > than 0, then the I > and Q signals will be upconverted and sent to the > outputs. As long as > the carrier frequency is greater than your signal > bandwidth, then you > only need either the I output or the Q output since > they are now > double-sided real signals. You can still use the I > and Q connectors > with an image-reject mixer if you need. > > Matt > > > > _______________________________________________ > Discuss-gnuradio mailing list > Discuss-gnuradio@gnu.org > http://lists.gnu.org/mailman/listinfo/discuss-gnuradio > __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
