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FORUM

Parameters explanation for Time-On-Air

Semtech Transceivers SX126x family
#1

Hello Experts,

Recently, I tried to compute the total symbols LoRa transimitted based on the description of datasheet, also I found that there is one similar issue SX126x Time-On-Air Calculation on the forum

however, some key info still has not been answered. could you help explan what is the meaning of number 8 which the formula mentioned if it cannot be disclosed too much key info? 8 symbols up-chrips or down-chrips?

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also, why there are extra 2 symbols (6.25 vs 4.25)when using SF5/6, comparing to other SFs. two more down-chrips symbols ?

#2

Hi @helonchan90,

As explained in this post, we cannot disclose the information you are requesting.

Please refer to the implementation available in the SX126x driver.

#3

Hello @mantoine Bro,

OK, although the meaning of number 8 cannot be disclosed, but if it is possible to try to explain why there are extra 2 symbols (6.25 vs 4.25)when using SF5/6, comparing to other SFs. two more down-chrips symbols ? I just want to know if it is down-chrip or up-chrip or not.

could you please help me understand more.

big thanks.

#4

Or try option ‘B’…

DIO Mappings Lora Mode, DIO0, 01’b = TxDONE (I’ve checked this and its accurate).
DIO Mappings Packet Mode, DIO0, 00’b = PacketSent (I’ve not checked this for accuracy).
Why even bother with a rather complex formula and floating point math… when the chip will tell you when its done. Just catch the interrupt and start your RxTimer. If you have an RTC, simple subtract start and end times and you have time on air (good to a millisecond with ST code)

Note: SX1276… sorry… BUT SX1261/2 have the same LoRa/FSK flags so should operate the same

Simon

1 Like
#5

Hello @simon.peacock00 Bro,

I think you misread my meanings. I just want to know the meaning of number 8 and why there are extra 2 symbols (6.25 vs 4.25)when using SF5/6, comparing to other SFs.

Concerning the time-on-air, the existing tool can meet my requirements.

thanks.