Anyone use the accelerometer to calculate jump height?

I thought a good use for the accelerometer would be to calculate & display jumping height in a field/widget/app during maximal effort jumps.

Assuming the jumper keeps arms still relative to body, then the time from liftoff to landing are "freefall" and hence 0 acceleration sensed.

We can use the duration of the 0 acceleration window to calculate height.

Seems there would be apps that do this, but I don't see any. Is there a problem with this idea? I can't be the first to think of it.

Now, I do see that the documentation says we cant ASK to turn on accellerometer data from a Field, but is it available without asking ... or is it sometimes available depending on activity? How does that work?

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jeromej_ over 2 years ago in reply to Mark Bolusmjak

I tried to measure vertical acceleration with the accelerometer sensor for instant vario detection (the baro gives to much noise and freq is only 1Hz...). My experience is:

- the watch/device moves independently of the human body. To measure the vertical accel (center earth reference), you need then to combine g, magnetometer and gyro sensors. We usually used Kalman filter (for nonstationary noise sources), but with Garmin, this is very difficult, due to several reasons (sensor freq, availability of data...);

- the accelerometer does not measure the accel of the human body, nor the accel of the watch, but the accel of a small mass inside the sensor. I believe your link explained that. You can check, your watch immobile on the table measures 1g, but there is no acceleration, your watch is not changing speed (Newton law). This complexifies the math.

To make a long story short, difficult to measure and calculate elevation or change in elevation with accel. The best would be with baro, but we need better acquisition frequency, not 1Hz.