Packets received with CRC_FAIL 100.00%

LPWAN Developer Gateways / Concentrators RAK2245 / RAK2243
1

Hi,

I have RAK2245-Pi-HAT edition. From its logs, I see following:
Sep 20 07:15:59 rak-gateway ttn-gateway[865]: # RF packets received by concentrator: 1
Sep 20 07:15:59 rak-gateway ttn-gateway[865]: # CRC_OK: 0.00%, CRC_FAIL: 100.00%, NO_CRC: 0.00%

I would like to understand if there is a way for me to see what packets were received and why CRC_FAIL is 100%?

I am new to LoRaWAN and if there is any documentation that I can use for this, please pointe me to it.

Thanks,

Ivica.

2

This is the statistics of the previous minute.
In this minute, you only receive one packet of lora data, this package data crc error, so CRC_ERROR is 100%

2019-09-20%2016%3A18%3A02
2019-09-20 16:18:02.png704Ă—70 12.5 KB

3

@ZhuQI seriously this is your answer :))))

4

You can try to use the node to send more data several times, and then look at this statistic.

5

I understand, but is there a way for me to see why CRC failed?

Maybe increase log level, or read through some documentation, some way to debug this?

Ivica.

6

Not really. This is a failure of the raw LoRa CRC added and detected by the LoRa chips themselves. You can get the packet data by changing the configuration (probably in global_conf.json) and if you know exactly what the packet was supposed to be you could compare that, but you would probably only know if you have your node dumping out the encrypted bytes on a debug serial port, or something like that.

In contrast, if it were the LoRaWAN “software” integrity check failing after the hardware CRC were satisfied, you’d probably see server logs mentioning a back MIC, unkown node, or wrong frame count.

Also note that it’s entirely normal for radios to pick up messages belonging to other people and other types of systems, which will be unintelligible to yours.

1 Like
7

Thank you, this is very helpful.

Ivica.