[USRP-users] How is gain distributed?

Josh Blum josh at ettus.com
Sun Feb 10 01:41:51 EST 2013



On 02/10/2013 12:32 AM, Sivan Toledo wrote:
> My N200+WBX reports a gain range of 38dB, which consists of 31.5 in PGA0 (a
> frontend programmable attenuator), 6 in ADC-digital, and 0.5 in ADC-fine.
> 
> When I set the gain to a given value, how does UHD distribute the total
> gain between the gain elements? I could not find this in the sources (I
> could not even find the strings "ADC-digital" and "ADC-fine" in the UHD
> sources; perhaps they come from the FPGA image).
> group

The magic is hiding inside of multi_usrp.cpp

So when setting the overall RX gain, the gain is first distributed to
the RF frontend, then to the ADC. For TX, the gain is first distributed
to the DAC, then to the  RF frontend.

-josh

> Thanks, Sivan
> 
> 
> 
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