Good evening everyone
I just became a member of TTN and successfully set up my first LoRaWAN gateway (using a RPi and a iMST iC880A as described here. Now I have tried to examine the communication range of this gateway. I logged all uplink packets using DR0 and noticed that there are no packets with an RSSI lower than -121 dBm received from my gateway. When I move more far away from the position of the gateway the RSSI decreases to -121 dBm and finally the message reception stops…The iC880A data sheet states that the minimum sensitivity is -137 dBm though.
As a next step I inserted an attenuator between my LoRaWAN device and the antenna to add step by step more attenuation to the uplink signal without changing my position - with similar results. Packets are only received, if the RSSI is -121 dBm or better.
Before I became a member of TTN, I used a LoRa gateway (simple LoRa Phy) implemented by my own, with similar Semtech LoRa chips. I was able to receive LoRa packets down to an RSSI of -138 dBm all the time. So is there a reason I can’t use the full link budget of LoRA within the TTN? What am I missing?