CMAltimeter update interval not sufficient for sport applications

Question

jumbopilot OP

Created Oct ’19

Replies 7

Boosts 0

Views 2.3k

Participants 4

Hi Guys,

since at least 2 years and usage of CMAltimeter, the method startBarometerUpdatesToMotionQueue(withHandler handler: @escaping CMAltitudeHandler) does not support modifying the core update interval fixed at 1 Hz (i.e. updates are output every 1 second).

This update rate is not sufficient for sport applications. The embedded hardware (MEMS) of well-known suppliers actually supports higher update rates than 1 Hz.

Why does Apple limit the update rate to 1 Hz and does not provide a similar update interval configuration interface as for accelerometer?

I've posted this as a new feature request 2 years ago without any apple feedback (via Feedback Assistant): Aug 31, 2018 at 4:35 PM – FB5637206 CMAltimeter: fastest update rate is limited to 1Hz (no configuration of update interval) 43939295

How can I start a discussion with Apple engineers to check feasability?

I'm missing an interface or method parameter like byInterval interval:TimeInterval in below method

Code snippet

open func startBarometerUpdatesToMotionQueue(withHandler handler: @escaping CMAltitudeHandler) {

...

}

Apple CMAltimeter Documentation: developer.apple.com/documentation/coremotion/cmaltimeter

Merci

Boost

Answer 1

KMT OP

Oct ’19

I'd suggest it's best to remember that an iphone is not only a phone first, it is a consumer-level product, in which case you may need to align your expectations accordingly.

If your suggestions have indeed gone unheeded, it may be because Apple either sees a conflict with their own internal goals, and/or those goals simply do not target the specific market you have in mind.

Otherwise their may be a market waiting for an improved resolution smart-phone hybrid/add-on that needs to be grassrooted.. Don't wait for Apple 😉

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Answer 2

jumbopilot OP

Oct ’19

My original question remains unanswered: How to reach Apple Engineers to start a discussion?

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Answer 3

KMT OP

Oct ’19

Dude... Besides the occasional Engr. discussing code level issues, Apple doesn't participate here in devForums

Otherwise, it's just us devs. Calm down pls...

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Answer 4

junkpile OP

Oct ’19

I would argue that there's no reasonable scenario where the altitude would change enough in 1 second to measurably affect the barometric pressure. Change my mind.

If you're writing an app for sky divers / BASE jumpers... or anything else involving flight... I think they'd have to be certifiably insane to rely on a phone instead of a professional instrument.

Can't you just use the accelerometer? It should be way more accurate over short intervals anyway.

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Answer 5

jumbopilot OP

Oct ’19

The embedded sensors support pressure changes/sensitivity around +/- 10 cm with an acceptable resolution, especially on last generation hardware.

Currently, with the fixed update rate of 1s, I do observe a time lag in barometric measurements under fast elevation changes around 0,5 m/s. The measurement is therefore unprecise and delayed.

Increasing the data output/update rate by factor 4 (interval of 0.25 seconds compared to fixed built-in update rate) would already satisfy multiple applications with more accurate measurements.

Yes, the accelerometer is helpful to detect an elevation movement, but due to measurement imprecision, an integrated acceleration as speed in e.g. m/s is difficult to reliably use.

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Answer 6

Claude31 OP

Oct ’19

Maybe you could find (and buy) a ticket for the next WWDC. That's the surest way to access tens of Apple designers. But pretty expensive.

External add-on connected to the iPhone would probably cost less.

Good luck.

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Answer 7

jumbopilot OP

Nov ’20

Seems there's not much help to be expected, neither from developers nor Apple :-(

I'm trying other channels.

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