Hi Andrew,
Concerning this issue, I´d like let you know that I succeed to obtain the LTE signal at the output of the LimeSDR mini (for both versions). Basically, I did two things:
First: the parameter “att_tx” in config file is not attenuation, but a gain as mentioned in OAI and LimeSDR-Mini - #126 by dast . The best values for the parameter of RU for band 28 I found are as follows:
RUs = (
{
local_rf = “yes”
nb_tx = 1
nb_rx = 1
att_tx = 70; # (this is not attenuation, but a gain)
att_rx = 0;
bands = [28];
max_pdschReferenceSignalPower = -24;
max_rxgain = 110;
eNB_instances = [0];
}.
Second: despite the OAI eNodeB is operating below 1.8 GHz, the first time I turn on the LimeSDR mini, I need to use the config file: LimeSDR_Mini_above_1p8GHz.ini instead of LimeSDR_Mini_below_1p8GHz.ini . Once the LimeSDR mini started with config file above_1p8GHz , I can stop the eNodeB and change the config file to below_1p8GHz. But it is not necessary to make this change, since it works well with the above 1p8GHz config file despite the eNodeB is operating below 1.8 GHz. I don´t know why this happens and I would be very grateful if you or someone could explain this. I got the LimeSDR mini config files from https://github.com/myriadrf/trx-lms7002m/tree/master/config-limeSDR
Best regards, Sindi