LimeSDR Mini and srsLTE


Running Ubuntu 18.04 and srsLTE 19.12.

Primarily trying to achieve stable performance using srsUE with commercial BTS. Basically srsUE can attach to BTS and gets IP and ping works. But attachment is very fragile. Perhaps only 1 time out of 5 succeeds. So something needs to be tweaked on LimeSDR settings?

How gain setting is supposed to work in srsUE and LimeSDR Mini? Despite changing tx_gain or rx_gain in ue.conf there is always same values in TIA, LNA etc when srsUE is started ?

“State of gain elements for Rx channel 0 (AGC not supported):
TIA: 9.00 dB
LNA: 30.00 dB
PGA: -4.00 dB
State of gain elements for Tx channel 0 (AGC not supported):
PAD: 45.00 dB
IAMP: 0.00 dB”

Are TIA, LNA etc supposed to be adjustable or are they fixed somewhere in srsLTE code? If so can they be changed before compilation? What commands can be used in ue.conf to set TIA etc.?

Also there is this strange error on TX:

“[ERROR] Tx Calibration: MCU error 4 (SXT tune failed)
[INFO] Rx calibration finished”

This TX cal error seems to be quite common but if there is a fix for this would be happy to hear.

BR, Oula

I’m not familiar with the stack, but would have expected setting a parameter called rx_gain to set one or more of LNA, TIA and PGA. You could take a look at the code and/or ask in the srsLTE community.

This doesn’t look good.

@Zack Not sure if you have any experience with running srsLTE?