Wrong RSSI value depending on frame counter and SF

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 :slight_smile: 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,


Hi Michael,

We observe the exact same behaviour with our gateway. We have a SX1301 communicating over SPI to a linux board. On linux, we have the lora_pkt_fwd package that handles all the communication with the lora concetrator.

What kind of software stack are you using ( or does the gateway use ) ? In your gateway, did you maybe try lora basicstastion ?