Reply to Bug in LoPy SNR stats? on Fri, 23 Jun 2017 09:39:12 GMT

pjoerke — Fri, 23 Jun 2017 09:39:12 GMT

Hi guys!

I'm using some LoPy's for a LoRa range analysis. With the stats() method I get information abour RSSI and SNR of the last received packet. When having a small RSSI of like -130 dBm the stats() method gives me SNR values of like -60dB to -80dB. I guess that is a bug because the Semtech SX1272 data sheet (the LoRa chip used by the pycom modules) says the minimum required SNR with SF12 is -20 dB to decode a packet. Is this a bug in calculating the SNR by the LoPy or have I a problem of comprehension?

Thank you for your help :)
Pascal

Reply to Bug in LoPy SNR stats? on Fri, 23 Jun 2017 10:12:11 GMT

pjoerke — Fri, 23 Jun 2017 10:12:11 GMT

I have to add some information: I can't use the lastest firmware because the modules are spread and so out of my reach :( I flashed all LoPy modules in April so that's the latest firmware I'm currently using.

While searching the web for my problem I found this:
https://github.com/Lora-net/LoRaMac-node/issues/104

It says that there is a bug in the SX1276 driver and so maybe in the SX1272, too. It misses a division by 4of the SNR value... And thats the factor I need. So: Does anyone know if this bug was a thing in the LoPy's too and had been fixed in the last weeks after my last update? I can't find anything about it in the last changelogs...