Most bands and watches do this claiming to do it through Pulse Oximetry. I [[User:DG|DG]] ([[User talk:DG|talk]]) suspect it may be accelerometry - activity based guessing in the bad ones. This is very bad because the difference between what accelerometry would predict and what is actually happening is very important information. | Most bands and watches do this claiming to do it through Pulse Oximetry. I [[User:DG|DG]] ([[User talk:DG|talk]]) suspect it may be accelerometry - activity based guessing in the bad ones. This is very bad because the difference between what accelerometry would predict and what is actually happening is very important information. |