I am doing some basic testing to check the power output performance of the SX1280 radio.
I have two identical boards with an SX1280 with signal routed to an SMA connector.
If I set the SX1280 to output at +13dBm with a CW, I get roughly this measured on an SA connected to SMA connector on both boards.
If I now connect both boards directly to one another and transmit LORA packet data from one to other and read the Params.LoRa.RssiPkt value (which seems to convert to dB inside sx1280.c), I consistently get 12dB less than transmitted values.
Eg, transmit packet at 0dB, received at -12dB through a very short wired connection.
What would account for that loss if connection to SA shows matching circuit is OK?
Is the modem interpreting the signal level in a way I am not understanding?