I’m sorry the RX2 window parameters appear to be a common topic but I just noticed something that I don’t understand and I couldn’t find it mentioned anywhere else.
I can see RX2 window downlink messages being sent at SF9BW125, as I would expect, but if the end device ignores about 5 or so downlinks they change to SF12BW125.
What I’m doing is a bit strange and probably not a valid use-case but it would be good to understand.
I’m forcing the end-device to use a specific DR and not disabling ADR. Nothing interesting happens if the end-device transmits at DRs above and including SF11BW125.
If the end-device transmits 20 messages at SF7BW125, with the ADR bit set, and then changes to SF12BW125 TTN starts sending ADR requests, as expected, using SF9BW125 869.525.
If the end-device ignores the ADR requests and continues transmitting at SF12BW125 the downlink messages change to SF12BW125 869.525.
Is this expected TTN behaviour?