[USRP-users] Quandry over B210 noise performance

Marcus D. Leech mleech at ripnet.com
Thu Jul 23 16:54:20 EDT 2015

On 07/23/2015 10:30 AM, David Browne via USRP-users wrote:
> I've been characterizing the noise performance of the B210 at the upper ISM band (5.8GHZ) and have been surprised to find that it is quite poor (22.3dB Noise Figure). I wanted to share my results (see below) and ask if anyone has ideas on how to improve the performance in this band. One suspicion I have is that the UHD is loading the AD9361 with a gain table that may not be optimal for this band but I have yet to dive into the UHD source code to verify this. I am also curious to know if the UHD controls AD9361 gain using the "Full Gain Mode" or "Split Gain Mode" (see AD9361_Reference_Manual_UG-570.pdf online). In general, it would be great to hear from anyone who has modified the UHD to control the AD9361 to optimize SNR or noise performance for their application's band and how much of an improvement can be achieved over the stock UHD configuration.
Also, tangentially related, I notice that you're running a fairly old 
(3.7 series) UHD. The gain tables have had some attention since then, so 
I recommend
   upgrading prior to taking any more measurements that you care about, 
since they may change.

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