Soapy Lime Transmit | Incorrect behavior of the gain variable

Projects LimeSDR
1

Hi, I am trying out the Soapy-LimeSDR-sink block in GNURadio 3.9 and am noticing odd behavior of the actual transmitted power in relation to the Gain setting.

My settings are as follows:

  1. Transmitting at 98MHz
  2. GNURadio 0.9
  3. Last git # of the soapy repo (6f97389)
  4. Using LimeUSB board
  5. Linux Mint / Ubuntu 18.04 base OS

Now, I’m measuring output power at different gain settings, and while the variable behaves normally from -12 to 50, odd things start to happen after that.

The max tx power peaks at gain=55

The max tx power actually reduces and the value at gain=60 is actually much lower than the value at gain=55.

2

Personally I use 52 as max gain, as above I start seeing too much noise.