For ABP LMIC_setDrTxpow()
needs to be called explicitly .
As far as I’m aware, for OTAA this is not required and defaults are used.
However, the following included OTAA examples do call LMIC_setDrTxpow(DR_SF7,14)
explicitly.
helium-otaa.ini
ttn-otaa-feather-us915.ino
ttn-otaa-feather-us915-dht22.ino
ttn-otaa-halconfig-us915.ino
Why this is done appears to be explained (only) in ttn-otaa-feather-us915-dht22.ino
:
// Set the data rate to Spreading Factor 7. This is the fastest supported rate for 125 kHz channels, and it
// minimizes air time and battery power. Set the transmission power to 14 dBi (25 mW).
LMIC_setDrTxpow(DR_SF7,14);
In lmic_bandplan_eu868.h
:
#define LMICbandplan_getInitialDrJoin() (EU868_DR_SF7)
In lmic_bandplan_us915.h
:
#define LMICbandplan_getInitialDrJoin() (LORAWAN_DR0)
In lmic_bandplan_au915.h
:
#define LMICbandplan_getInitialDrJoin() (LORAWAN_DR2)
Questions:
-
I assume that for OTAA
#define LMICbandplan_getInitialDrJoin()
defines the initial DR/SF used for a join if no SF is explicitly set by the user.
Is that correct? -
My interpretation of “RP002-1.0.2 LoRaWAN Reginal Parameters” p31, for
US915
is that LORAWAN_DR0 is the same as DR_SF10.
Is that correct? -
My interpretation of “RP002-1.0.2 LoRaWAN Reginal Parameters” p31, for
AU915
is that LORAWAN_DR2 is the same as DR_SF10.
Is that correct? -
Does this mean that SF10 is the standard SF to start a join for both
US915
andAU915
? -
If not, then why is SF10 set as default?
-
The
US915
OTAA examples which callLMIC_setDrTxpow(DR_SF7,14)
explicitly apparently do this to speed up the join process and use as little power as possible. This will however only have a positive effect if the gateway is near enough to use higher DR’s.
Is it correct to assume that setting SF explicitly to SF7 (for ‘US like’) is application dependent or would you advise to use this in general? -
In example
ttn-abp.ino
(and other examples)LMIC_setDrTxpow(DR_SF7,14)
is called independent of any region settings check.
Is it safe to callLMIC_setDrTxpow(DR_SF7,14)
for all regions? -
What about Tx power? Is there one default value for all regions or is there a separate default value per region?