There have been a couple of questions around here about determining whether or not your band is really working and I know I wasn't certain at the start either. Deep and conscious breathing sometimes work, but I still was skeptical of it occasionally. However, even in a noisy signal, I found that alternating periods of holding your breath and breathing naturally are very good at distinguishing the effectiveness of your setup and readings. It also points to some more interesting applications.
Dips in moving average are the ends of periods of holding breath. Of course, do this intelligently and don't push yourself, if you do it at all.
"Cerebral blood flow-related signal changes during breath-holding"
https://pubmed.ncbi.nlm.nih.gov/10472977/
Thanks for this! Yeah this is a really noisy signal, but as you noticed the larger trends (which is mainly what we care about) are still fairly apparent. This is a fairly non-issue now on the new sensors, though there will always be some AC interference when plugged into the wall. The V1's are annihilated by AC but on the new ones it just obscures pulse now.