I think not. I was wrong; see Jaap’s smart solution below.
You need to set the Spreading Factor, and while checking one channel, you’re ignoring the others:
https://www.thethingsnetwork.org/forum/t/four-channel-rpi-gateway-board/1794/3
…and:
https://www.thethingsnetwork.org/forum/t/rn2483-promiscuous-mode/2101/5