I am using the LimeSDR USB (Type A) for a prototype development. Currently I am using the LimeSuiteGui software to gain familiarity with the LMS7002 RF chip.
My question here relates to Rx calibration when I have an in-band signal present.
I have noticed that I lose either the Q signal (the signal gets rectified and maintains a very low digital level or is zero) when Rx calibration is performed when an in-band signal is present in the front-end. I am performing Rx calibration by pressing the Rx calibration button in LimeSuiteGui.
If I power down the LNA before Rx calibration is performed then everything works fine after calibration & LNA is enabled.
The issue seems to be related to the in-band signal level - if I terminate the input and perform Rx calibration, then the system works fine.
So my question is:
Does the LNA have to disabled before Rx calibration is performed?
My set up is:
RF Bandwidth: 25MHz
LNA Gain = Max
TIA Gain = Max
PGA Gain = 19 dB
Thanks for your help.