[Discuss-gnuradio] How does Rx Gain affect the incoming signal? GNURadio IEEE 802.11a/g/p

[Cristian Rodríguez]

Hi all.

I'm trying to understand how Rx gain, the paremeter that is set in the USRP Source block, affects the input signal. I would like to have an equation for that.

I'm doing the next experiment:

• I take the input signal from the USRP Source block to a MAG^2 block.
• From MAG^2 block to a moving average with a window of 50K.
• My sample rate is 10M that means that my moving average is calculated over 5ms.
• I'm sending a signal from a transmitter each 5ms.
• Finally I capture the value of the moving average, which is always around an average value.

Now, I change Rx gain and it is what i get:

The value of the output of the moving average is changing very strange. I was trying to write an equation for that, but i wasn't able, i used Rx gain in dB, in dBm as a constant, but i wasn't able to build a relation. In an equation i'm doing as follow:

Then I think that if I include Gtx, my equation results in:

But that doesn't make sense with the data that I get.

I would really greatful if someone can explain where is my mistake.

Thanks in advance.

Best regards,

Cristian