[USRP-users] TwinRX tuning timing

mleech at ripnet.com mleech at ripnet.com
Fri Jul 14 15:33:58 EDT 2017


The frequency tag is inserted at some point shortly after the
command-set is issued to the hardware.  There's no way for the various
bits and pieces to tell when the underlying (mostly analog) hardware has
converged to an "acceptable" steady-state operating mode.  PLL
synthesizers don't instantly switch from one frequency to another,
digital (and analog) filters have group delays, etc. 

The time to achieve steady-state can vary from hardware-type to
hardware-type, ambient temperature, size of the frequency step, etc. 

On 2017-07-14 15:10, Eugene Grayver via USRP-users wrote:

> I am running some experiments to understand the timing of TwinRX tuning.  A very simple experiment shows that the tag indicating a frequency change is not placed at the right sample.  Here's a capture: The dashed line indicates the tag sample number.  However, there's clearly something happening before the tag.  Note that I am not using timed commands for this - just a regular tune request. 
> 
> _______________________
> Eugene Grayver, Ph.D.
> Aerospace Corp., Sr. Eng. Spec.
> Tel: 310.336.1274
> ________________________ 
> 
> _______________________________________________
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> USRP-users at lists.ettus.com
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