I sent this email to Roger last Thursday, right after my first run. Wanted to share it with this Developers Forum:
Good workout today. Did a 4 mile run, pretty much steady pace, but there were hills - so the SmO2 wasn't steady.
Placement: Vastus Lateralis Right Leg - Outside edge of knee cap, up one third of the distance from knee to hip.
Started at 65 - rose to over 75 during stretching.
Got into the run and settled in at about 45 to 50. Hills seemed to push the numbers down a bit.
Walked at 2 mile mark (about 20 seconds) to see if the systems was responsive to recovery, and it worked as expected. I went over 90.
Got back into my running pace and settled in around 40 for a while.
Hit an up hill grade, a tough one, and saw it go into the 20's - even a few 12's and 13's. I am not sure I believe it was really that low, but it was certainly directionally correct.
Hard run for the last quarter mile - pushed it down to the 35-40 range.
Recovery at the end got up to the high 80's. Slowly working it's way down when I had to take it off so I could shower and head off to work.
I think I saw a few instances where it displayed some really odd numbers. I don't think it's physiology or road noise from my feet pounding on the ground. Looks to me like it's look-up table issues - but your theory about electrical noise could be right as well.
I just think, overall, that it did what I expected it to do.