I am new to developing RF applications but am tasked with developing a signal profile for a LoRa sensor node. I want to use the lsnr and rssi values calculated by the gateway to map signal strength over a set of environmental parameters. I need to explain how the rssi and lsnr values are calculated, but I am unable to find this in the source code. I searched the semtec radio source code, but it seems like it is pulling the rssi value from a register. Can you refer me to where the libraries calculate the RSSI value by measuring received power or voltage? I am also trying to find the source for the lsnr value.
I have the NUCLEO-F746ZG (+ RisingHF LRWAN_GS_LF1 LoRa riser) configured as a gateway and a NUCLEO-WL55JC2 setup as a node. The gateway and sensor are communicating as shown in the images below. The lsnr and rssi values I am trying to explain are the values reported by the gateway in these images.
Thank you for any help you can provide.
