We are testing RAK4200 modules at 868 MHz.
The minimum RSSI level we get is ~ -127 dBm, but the documentation for the SX 1276 for the 125 kHz band and SF 12 says that the RSSI level should be about -136 dBm.
Why is it so?
How can I control the LNA gain and LNA Boost parameters?
How can I enable modes with bandwidth less than 125 kHz: 62.5 kHz, 10.4 kHz, 7.8 kHz?
How can I enable FSK / OOK modulation modes?
Thanks for answers.
With the default firmware of the RAK4200 you cannot do any of the changes you mentioned.
The minimum RSSI level is not only depending on the RAK4200, but as well the antenna cable, the antenna connector and the antenna itself.
The -136dBm is best case and not guaranteed.
The RSSI level is an internal parameter of the SX 1276 receiver and is independent of either the antenna or the type of connector. It can only depend on the level of interference. If the interference level is higher than -136dBm, then this RSSI level cannot be achieved. But if the interference level is lower, we should see this level. But this level depends on the gain parameters of the LNA.