I have tested the following configuration:
iC880a + RPi 2 with The Things Network software from https://github.com/ttn-zh/ic880a-gateway
I am using 5V 2500 mA power supply for RPi 2 (I plug it into micro USB port).
For the node I use HopeRF RFM95W with Teensy 3.2, and a code from https://github.com/tftelkamp/arduino-lmic-v1.5 I tested it using both SF7 and SF12.
When those two are connected I am getting quite a lot of CRC_FAIL indications (usually between 25 and 50%, sometimes reaching 66%). I feel this is not normal for a simple test with those devices on the same desk. I have also tested the same node with a single-channel test gateway from tftelkamp github repository (based on HopeRF RFM95W as well) and I have not seen this problem (I would get some CRC errors but only for long ranges, not when node and gateway are close to each other).
Has anyone seen any issues like that? I looked at the forum and it seems some other people had similar problems but I could not find any consistent answers. Somebody pointed to power supply being not powerful enough. What power supply should be used in such configuration? What are the methods I could use to debug this system further? Any help is welcome!