Other Motion sensor, health app

[gsusser]

I'm a little late to the game, I just discovered the motion sensor. I was trying to understand how a 3rd party pacer app works for walking. I'm still a bit confused. How does the motion sensor pick up maps and measure speed? Is it by satellites? I ask because sometimes I'm out of satellite range. The app I use (Pacer Pedometer & Step Tracker) is uncannily accurate except for pace and speed, though it's not that far off. I compared it to my running watch.

While I'm here, what is the best app to measure distance, pace and maps for walking or running.

 

[SpaceGrayAlways]

Your iPhone's accelerometer can actually determine each step based on motion. Distances, step length, details like that may also include additional information, and workouts (on Apple Watch) also track GPS location - but this can be disabled.

 

[now i see it]

It's a combo calculation of GPS and internal accelerometer to count steps

 

[gsusser]

Thanks for the responses.
I'm trying two 3rd party apps that measure walking statistics. I am also comparing the apps to a GPS watch that I know is very accurate. Why do all the numbers vary? It's mostly only the pace that varies. More specifically, why do the apps and health app vary? I was thinking that the 3rd party apps got its information from the motion sensor, no?

 

[now i see it]

I've tested the iPhone against a known accurate pedometer and against actually counting steps and the iPhone when carried in a pocket is unreliable at counting steps. It's also unreliable when hand held. It may be more reliable if mounted in a holster that's clipped to a belt — but I'm certainly not going to use something like that and it's likely few others will either.
What I did find when using the iPhone to count steps was that it is reasonably consistent - the identical walk done multiple times roughly came up with the same number of steps good enough for general referencing.

My conclusion was: If accurate counting of steps is my thing - get a dedicated pedometer. If a casual ballpark number was good enough, the iPhone was ok

As for GPS accuracy, all apps that I've used calculate distance a bit differently. None are exactly the same. There's more to calculating distance using the GPS receiver than receiving data from the satellite.
There are "filter levels" to account for that takes into account false movement due to GPS inaccuracies and the required distance threshold between waypoints. Each app filters the GPS data differently depending on what the developer thinks works best - thus the output varies between each app.

If you want a really accurate GPS - buy a dedicated GPS unit

 

[gsusser]

That's all I ever wanted to know, lol.

I'll stick with the iPhone. I knew it was fairly accurate, I was just curious how it worked.
The only open question is how 3rd party apps get info from the motion sensor and why it varies from the iPhone and between apps. I like the interface of the Pacer Pedometer and Steptracker and would like to continue using it and probably will. Just curious why the readings are slightly different from the iPhone. Strangely, distance and speed mostly correspond to my GPS watch but pace is off by about 8%. That doesn't seem mathematically plausible.

The drawback of my GPS watch and probably any dedicated GPS device is difficulty at times picking up a satellite signal. Otherwise, I'd stick with the watch.