Hello BoRRoZ,
Thank you for the reply,
Still the 8 symbols i’m talking about aren’t those of the preamble. As you see:
Time on Air = T preamble + T payload
with
Tpreamble= (NbPreamble (8) + (symbols added by radio)4,25) x Tsymbol
and
Tpayload = NbPayloadSymbol x Tsymbol
And according to LoRa calculator, the NbPayloadSymbols is calculated with this formula:
I am looking for the meaning of those 8 symbols (red circle). In the formulas of the calculator the nPayload is independant from the 8+4.25 symb of the preamble.