I am trying to characterize the Tx of my limeSDR mini. I connected the limeSDR_Tx directly into a spectrum analyser, transmitted a sine wave by using GNURadio and measured the power [dBm] using the spectrum. I encountered 2 issues:
- Max power is -17dBm as oppose to the expected 10 dBm.
- The power output is very unstable, get a peak every 100 MHz approximately and then the signal falls back down.
- I repeated a similar procedure with limeSDR (not mini) and encountered similar values, so it’s probably not the specific device that is broken.
Here are two images, the right one is a scan over the peak frequencies, to see the overall performance and the left one is a scan with a smaller step of 5 MHz around 900 MHz to demonstrate the unstable amplitude I’m seeing.
I am wondering, is there a way to fix this?