Dear community,
I am a researcher from germany who has conducted several LoRa related studies [1]. Our group recently ran into an issue which we can not explain. We believe this is a very strange bug, which should be further investigated. Here is the situation:
We can conduct reproducible! measurements in a labotory enviroment which show that the reported RSSI by a gateway depends on the value of the FrameCounter. In more detail, if the frame counter is in the range from 256-512 or 768-1024 the repoted RSSI fluctuates heavily while in the range from 0-256 and 512-768 it is stable. Yes, this is a depency modulo 256 However, only with an SF12!
We have observed this behaviour with the following gateways:
- TTN Indoor Gateway (Semtech SX1308)
- DLOS8 Outdoor LoRaWAN Gateway (Semtech SX1301)
- iC880A-SPI LoRa Concentrator (Semtech SX1301)
- Multitech MTCDTIP-L4E1-266A-868
Using the following nodes:
- RAK Wireless RAK4631 (SX1262)
- Heltec AB01 (SX1262)
- PyCom LoPy 1.0 (SX1272)
- Adafruit Feather M0 LoRa (RFM95W (SX1276 LoRa based))
See the following plot as an example of this issue. We have more of these plots, but I am only allowed to post one as a new user.
We can not observe this behaviour on a simple self-build single cannel gateway. Therefore, we believe the Gateway is an issue.
So, anybody has an idea?
With kind regards,
Michael
[1] https://scholar.google.de/citations?user=e_bBQ_8AAAAJ&hl=de