Static noises, particularly during first few seconds

[Erhannis]

Ubuntu 20.04.3 LTS

When I run minimodem, e.g. ./minimodem --tx 100, I often get static or crackling - like, >70% of runs. The static often occurs primarily towards the beginning, and then it seems to get straightened out, and subsequently I may occasionally hear a little crackling. It can sure mess up transmission, though. Any idea why it's happening?