Re: Spurs in UBX-160 Daughterboard with USRP X310

[Marcus Müller]

Hi Dor,

>  1. How to change the to integer_n tuning? Should I just type "mode_n=integer" 
> in the
>     Device Address parameter of the UHD: USRP Sink block in the grc?

yes. Or, better, instead of just tuning to the target frequency, you can pass a 
uhd.tune_request_t to uhd_usrp_{sink,source}.set_center_frequency, like this:

my_uhd_block.set_center_frequency(uhd.tune_request_t(
              target_freq = 2.4e9,
              args="mode_n=integer"))

(you can also use a uhd.tune_request_t in the RF frequency fields of the GRC 
block)

Note that you're probably best off using tune_request_t anyway, as it allows you to tune 
your LO far away from your band of interest, given the analog bandwidth allows for that, 
using `target_freq=` and `rf_freq` or `dsp_freq`.

For more information on tuning, see the UHD manual [1]

>  2. How to know for sure what the mode(integer of fractional) of the NCO is? 
> Can I print
>     its status/get it somehow? 

looking at the UHD source code: the routines responsible for tuning just themselves check 
for "mode_n" being set to "integer" in the device or tune request arguments.

Best regards,
Marcus

[1] https://files.ettus.com/manual/page_general.html#general_tuning