I am not a tech expert by any means, far from it, but my general understanding is they have comparable systems - gyrometer, altimeter, and accelerometer that work together to identify movements, including steps. An iPhone carried in a hip pocket is more accurate acting as a pedometer than a watch is only because your hand movements won't be measured if you are say pushing a grocery cart (why a lot of women it seems hold on to their carts with only one hand, because they want their step credits), or walking with your hand steady in a pocket and not swinging your arm to trigger the accelerometer. And similarly extra steps may be credited if you are an animated talker and flail your arms around a lot, or do some other activity where large arm motions may be counted erroneously towards steps: kneading bread or standing and playing ping pong for example. With ping pong you may not be walking much but a watch will count more "steps" than the phone that is in a hip pocket doing the same activity because you're swinging at a ping pong ball regularly but not necessarily taking a lot of full steps. Then add GPS location tracking to the other tools and that's how they both know you're moving at 30 or 65 MPH in a car and not out on a casual 2.0 mph walk, or 6.0 mph run.
Another thing apple health does is estimates step length as you go about your day, which normally is about 0.4 of someone's height but can vary especially with short or long legged folks. But it's typically consistent as it's averaged dozens of times a day when walking on level ground outside. So theres a record of what JO's average step length has been, somewhere in his health data. Was anything said about the nearly doubled step length of his phone at one point"? 1.992 feet per step for 170 steps at 12:21 vs 3.598 feet per step for 80 steps at 12:24? These are actual steps counted, based on triggering an accelerometer in his phone 170 or 80 times, not flying in the air or riding in a car once. That doesn't seem like the same person casually walking with his phone at 12:24 as it was at 12:21 IMO.
The 3.598 feet per step would be about 1,467.5 steps per mile, which is less than a 10 minute mile running pace for a 6'2" male per the American College of Sports Medicine. Seems someone was sprinting.
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Related to this particular situation where we are questioning the cell phone location, there's also the concept of Bayesian probability -
a measure of believability or confidence that an individual may possess about the occurrence of a particular event. That's how and why that "blue circle" changes sizes when you locate yourself on a mapping app. The smaller the circle or blue dot, the stronger the signal and confidence (probability) the phone is in that circle or spot. But confidence level changes as information is continually gathered, and with cellphone signal and wifi strength especially. When the blue circle is large it's giving an estimate that it's in that area based on signal strength but other info as well. Such as if you're moving 40 MPH, the dot is likely going to be placed on the road moving along due to probability, and not in the forest you're driving next to. If you're sitting in your home as I am, the circle should be small because I have good cell signals and wifi and spend a lot of time at home, it knows this. And sometimes it pinpoints me in the correct corner of the house. And sometimes (usually) the circle is big enough it looks like I could be in my neighbors house, as it currently thinks I could be. But I am not, nor have I ever. It's always adjusting and guessing, and it's never 100% accurate. Who hasn't panicked when they think their kids car is in a ditch because the gps puts them there and it hasn't moved in ten minutes and then you go check on your kid only to find they are not in said ditch and did in fact make it to practice a half mile away from the ditch and the gps didn't update just because the signal was weak and you feel stupid because your kid was just ignoring your texts again? Just me? Probably.
Anyhoo, I'm off the rails now from the original question and I have not watched or read everything but I also found it unbelievable the defense didn't discuss how these locating probability laws work to potentially place his phone in the house, not the yard. Unless I missed that. So when it was argued the blue circle didn't put him in the house, I disagree, because the blue circle did in fact overlap part of the house. I can't find that photo for some reason if anyone has it. Assuming geolocating is turned on, a cell phone is always taking in information and making a best GUESS to pinpoint its location, based on prior experiences and signal strength. Geolocating is just probabilities, and they will change when new evidence is brought to light. Sit and watch your location on a map for bit and you'll see the circle get bigger and smaller as it gathers info and you're not even moving. My guess is the one blue circle picture they used (or at least I saw) was the one that was most favorable to him not entering the house, and yet it still overlapped part of the house. And if the phone was in the basement, well we all can probably accept that the signal strength isn't going to be as great in a basement as it would be in a front yard without walls interfering. I'd expect that circle to be a lot smaller if the phone was in fact never in the house as it would likely have a stronger cell signal and I doubt a cop has free open auto connect wifi for JO's phone to use be more accurate to pinpoint the phone location.
Sorry for the ramble, no idea if these things were covered here previously, I can't keep up. Hope this makes sense, I'm a wee tired.
MOO IMO some professional, some not.
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