It's all about the Software

Hello, first, thanks for awesome software.

Second, while using the Ettus B210, I notice that when setting the gain to a "low" value, the noise floor goes up, and when setting the gain to a "high" value, the noise floor goes down. Also, when selecting AGC, the noise floor is about 30dB higher than the highest level I can achieve with the gain control menu, which occurs at the "0dB" gain selection. This is the opposite of what one would expect; with low gain, signals and noise should be lower than they are at high gain.

To summarize, the lowest possible gain is achieved by selecting 76dB, the highest possible manual gain is achieved by selecting 0dB, and the familiar aggressive UHD AGC behavior is selected by the 'AGC' option, so that part at least is working correctly. It's almost as if the menu should be labelled "LNA attenuation" or something.

Best,
Mike

Noise floor is not a good measure given the oddities that sampling can provide. What happens to an actual signal?

I don't have one of these things. I wonder if it is one of the front ends that set attenuation rather than gain. Let's start with what happens to a fairly strong signal as you make adjustments? (And a 76 dB range seems er ah just a little odd to me. Even the rtlsdr dongles aren't THAT far out in the void.)

{^_^}