Re: [Discuss-gnuradio] Tx path diagram

[Eric Blossom]

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