Continuing the discussion from Spreadsheet for LoRa airtime calculation:
After searching everywhere on Semtech’s documents ,LoRa calculator, and the LoRaWAN specifications. I still don’t understand why a Payload has at least 8 symbols that are independent than payload size, SF, CR,…
the 8 symbols i’m talking about aren’t those of the preamble. As you can see here:
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.
Does anybody have an explanation for those 8?
Much appreciated,
I check the patent EP2763321, the 8 default symbols should be the fine synchronisation symbols, and the -4FS should be the smoke bomb, so only 4 fine synchronisation symbols.
I suspect not, not for TTN which is what this forum is about - but it’s a question of general interest, just be aware that for LoRaWAN we only do TTN here.