I’ve recently bought a LoRa Node pHat for my raspberry pi. I’m told by the vendor that its firmware came from RAK wireless. I have noted that when I run a join-otaa command to join with over the air activation, that the transmissions form a very specific pattern. Most are ~75ms long. Eventually there’s one at double that duration (presumably the next spreading factor up?). A few more at ~75ms then one at four times that. A few more a ~75ms then one at eight times that. A few more at ~75ms then one at sixteen times that. Then stop. Is this procedure a defined LoRa method for joining OTAA or is it something that is specific to this (or perhaps all) RAK modules? Presumably it tries increasing spreading factors to increase the chances of getting through if the lower spreading factors have failed? Thanks for any light that can be spread on this.