[USRP-users] Phase after Freq Hopping

Piotr Krysik perper at o2.pl
Fri Mar 15 09:51:39 EDT 2019


W dniu 12.03.2019 o 17:49, Patscheider, Dominik via USRP-users pisze:
>
> Hello ,
>
>  
>
> For a Radar I´m transmitting and receiving with the USRP X310 samples
> on different frequency steps.
>
>  
>
> For instance, after 4 frames I´m coming back to the first center freq
> and continue this a few times. Hope the following description helps…
>
>  
>
> f3                   |phase4|       |…|
>
> f2                  |phase3|       |…|
>
> f1               |phase2|       |phase6|       …
>
> f0            |phase1|       |phase5|
>
>                 t ------>
>
> According to the freq adjust every frame starts with a new phase.
>
> Phase 1 ≠Phase 5
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>  
>
> Is there any possibility to get the same phase after returning to the
> same center freq? Phase 1=Phase 5, Phase 2 = Phase 6,…
>
>  
>
>
Hi Dominik,

Can you describe what you want to achieve exactly? Probably you need to
know phase relations because you want to do coherent processing of the
signal. But from your description I don't know:
-why on your ASCII art the signals transmitted on different frequencies
seems to be overlapped?
-which you part of it you want to process coherently?

I also often use USRPs for radar transmissions. Issues with predicting
initial phase difference of the received signal, in relation to digital
waveform that is being transmitted, are much easier to overcome when you
use timed commands to set the frequencies on Rx and Tx side
synchronously (if you use UBX or SBX daughter-boards).

Best Regards,
Piotr Krysik




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