I'm using Software Defined Radio NI USRP 2922 (Universal Software Radio Peripheral). I know that USRPs are uncalibrated devices. In many exampls you can set the so called Tx or Rx gain (as in the picture below).

enter image description here

Now, I know that this does not correspond to the real power of the transmitter, nor is it a "gain" of the antenna - the most appropriate term here would be "transmitter channel gain", right?

So I would like to know how this transmitter channel gain process is implemented, how it is calculated, and how it works in practice (since a particular gain value doesn't correspond to a particular power level).

  • \$\begingroup\$ Electrical engineering is a very broad field. Therefore you should define acronyms that are not common. This category would include USRP. Thank you., \$\endgroup\$
    – Barry
    Commented Feb 2, 2021 at 2:47
  • \$\begingroup\$ I edited my post. USRP is software defined radio from National Instruments. My model is NI USRP 2922. \$\endgroup\$
    – MagicMan
    Commented Feb 2, 2021 at 2:53

1 Answer 1


You set gain (attenuation) in hardware.

NI USRP 2922 is basically N210 + SBX from Ettus research. From their pages and knowledgebase you can get better description (and schematics) than NI provides. In knowledgebase is mentioned that used dautherboard (SBX) use HMC624LP4E attenuator.

Just to be sure, NI USRP 2922 specifications have exactly same gain range and step as does the mentioned attenuator.


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