Re: [Discuss-gnuradio] Tx path questions

[Eric Blossom]

On Tue, Jan 06, 2009 at 10:41:22AM -0300, Ronaldo Nunez wrote:
> Thank you for your answer Mr. Blossom,
> So, the tx path is something like this:
> 
> PC --> USB --> CIC(FPGA) --> AD9862 --> Daughter Board --> Antenna
> 
> There is two frequencies involved in all transmissions:
> * A signal frequency (f_signal), generated by sig_source_c().
> * A RF frequency (f_tx), set with target_freq in tune().
> 
> The signal (which frequency is f_signal) is interpolated by a factor between
> 4 and 512 on CIC interpolator,
> after it is up converted to the RF frequency (by the NCO on fine modulator),
> so it is moved +- fdac/4 or fdac/8 on coarse modulator.
> The signal will be converted to analog (DAC) and amplified and transmitted.
> 
> 
> Be free to correct me, I need to know exactly how USRP and GNUradio works.

Yes, you've got the basic path right.


Please see also the USRP FAQ, available here

  http://gnuradio.org/trac/wiki/UsrpFAQ

or as a pdf

  http://gnuradio.org/trac/attachment/wiki/UsrpFAQ/USRP_Documentation.pdf

Eric