A test for my Arduino working with NRF24L01+PA transceiver

There are two computers, one is called Joker and the other is called Batman. They use Morse code to communicate. The microcontroller is Arduino and the wireless transceiver is NRF24L01+PA. I find that sometimes it works fine especially at night when few people are in the lab, but sometimes transmission failed (both of them can not talk to each other or just one-way communication works). Not sure if the reason is the interference from wifi.