How swim tracking works on the Apple Watch Series 2 and 3

Source: www.imore.com --- Wednesday, October 04, 2017
PopSci dove into the science behind Apple's swim tracking on the Series 2 & 3 Apple Watch, and it's a fascinating read. "Damn it, Jim, I'm a roller skater, not a swimmer!" — me, more or less When I reviewed the Apple Watch Series 2 and its swim-tracking capabilities in 2016, I felt more than a little under-prepared to do so, largely because I don't swim. I can swim — well, to the extent that I could fall out of a boat and keep myself from drowning until help arrived. But if you ask me to demonstrate the difference between a butterfly and breast stroke, or the proper form for a flip turn, I might well look at you like you'd grown an extra head. I eventually tested swim tracking the way I suspected many Apple Watch users were going to swim: In a pool and by the beach, exploring the water . But even my lackluster swimming abilities and testing didn't stop me from being curious about the science behind what Apple had accomplished. From my review: When you swim in open water, your Apple Watch will create a GPS-based swimming map for you to look at afterward. GPS signals don't penetrate water, so the Watch grabs a connection any time your hand is above water mid-stroke. This pitch sounded pretty dicey to me — that's a very short amount of time to properly talk to a satellite — but in my brief 10-minute test, it worked pretty well. (Admittedly, not hard to do, given that I swam straight out, then straight back.) The resulting workout i ...

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