[USRP-users] Automatic Gain Control

Marcus D. Leech patchvonbraun at gmail.com
Fri Nov 22 10:11:51 EST 2019


On 11/22/2019 02:38 AM, Sergio Parreño Gómez via USRP-users wrote:
> Hi all,
> We have a X310 SDR  with release version 3.14.1.1 of UHD. We are 
> obtaining IQ samples from 4 channels.
> My question is, X310 includes Automatic Gain Control in samples 
> depending on signal power? I say that because in the datasheet I 
> couldn't find any information about that but I observed differences in 
> power level depending on if SDR gives samples in int or in float format.
>
> Clarification: When SDR gives samples in int format and after I'm 
> interpreting that sample the signal power is different than if I 
> obtain samples in float format.
> Best regards
> Sergio
>
>
The float values will be scaled into  {-1.0,+1.0}.   The "wire" format 
will always be in 16-bit complex short ints, so the SDR itself has no way of
   knowing what host-side format you're using.

I don't think ANY of the daugter-cards that are normally used with X310 
have hardware AGC of any kind, and the DSP engine in the X310 doesn't
   implement any AGC of any kind.





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