Sorry if this is a newbie question. Wandering around the bands (HF), I often see someone transmitting while they're changing frequencies. I'll be listening to a frequency, and on the waterfall you can see someone transmitting as they fly through the band, generally not stopping, and as they pass through the frequency where I'm tuned, it seems like it's just a carrier. I've sometimes seen them weave and go backwards for a bit, doesn't seem like something natural or repetitive. Is this someone trying to tune their auto tuner? A lid? Something else? No doubt this has been discussed before, but I couldn't figure out terms to search for it. Thanks.