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Ever since I got an Android Wear smartwatch, LG G Watch R, which has an incredible pressure sensor with 75Hz sample rate and amazing always-on display, I wanted to have an altimeter on it with various useful features for BASE and skydive. Besides smartwatches, more new smartphones get barometric sensors. However, I haven't found any good app that would fit my needs, neither for smartwatches nor for smartphones, on any of the 3 app stores.

After I wrote L/D Vario:



- an app for thinking wingsuiters that works on 4 platforms (Android+Wear/iPhone/Windows) - I want to use my advanced data analysis algorithms and cross-platform engine for something else useful. So, here we go...

I'm going to write an app, Smart Altimeter, that will work on any device with a barometric sensor. The app will be free. (However, I don't exclude the possibility that some advanced, optional features could be purchased for a small fee - I want to eat drink beer, too, sometimes.)

The main emphasis will be made not on traditional visual use in skydive freefall (since today's screens are still quite poor in direct sun), but on things that smart devices can give to us that "dumb" altimeters can't - taptic and audible feedback, useful features on mountain hike in BASE or a ride to altitude in skydiving, data recording and analysis, and so on.

I am all ears listening to your wishes. Let's go!

I would appreciate your input on barometer sampling rate in your device if it has one. How: download L/D Vario (free app, links above) and tap the "i" icon, you will see the info about sampling rates of accelerometer, barometer, and GPS:



I'll start:

LG G Watch R: A(ccelerometer)=200Hz, B(arometer)=75Hz, G(PS)=N/A

Samsung Note 4: A=200Hz, B=5.6Hz, G=1Hz

iPhone 5: A=104Hz, B=N/A, G=1Hz

Lumia 520: A=80-90Hz, B=N/A, G=1Hz

Your turn!

Droid Maxx: A=102.6Hz, B=25.6Hz, G= (measuring) never returns any results.

Samsung Galaxy S6

Thanks guys.

> Droid Maxx: A=102.6Hz, B=25.6Hz, G= (measuring) never returns any results.

Getting precise location (satellite-only) might take some time, even if maps show your location using WiFi/cellular positioning. You may need to switch to Fine Location in Android settings.

26Hz sounds good! To derive descent rate from noisy altitude data, very aggressive smoothing and differentiating algorithms are needed that use wide window (number of previous samples). With 26Hz barometer, approximately 0.5s lag would be expected in outputs, which is still good.

> Samsung Galaxy S6

I guess it's the same sensors as in Note 4. Do you have this bug where the barometer will always show 37ft when you use your Samsung device above 4000ft? It's a known bug (search for "stuck barometer Samsung Note"). It only does it if you turn it on at already above ~4K ft (like if you live at high elevation), if you turn it on below 4K and go up with a plane, it functions normally. Unfortunately, Samsung has done nothing to resolve this issue.

You can access diagnostics on Samsung phones by dialing *#0*#, then click on Sensor button and observe if barometer readings are fluctuating or stuck at 1011.9Pa.

I will to turn it on (above 4K) next time I go for a sky jump and see if it gets stuck.

It looks like the flatline barometer is fixed with the latest update (AT&T Note 4, at least).

Anyone with iPhone 6/6s/+?

Here are the stats from iPhone 6 - the barometer value is actually blinking, and it varies from about 0.5hz to 0.9hz

Thanks!

Anyone with 6s/+?

So far, the fastest barometers are:

1. LG G Watch R - 75Hz
2. Nexus 4 - 30Hz
3. Droid Maxx - 26Hz

Hello Yuri!

I've done a test using an iphone6+ of a friend of mine (thx Diego).

Accellerometer 101.6Hz
Barometer (blinking) 0.8 Hz
GPS 1Hz

Keep up with the nice work!

Cool. Anybody with any LG smartphone with a barometer? It looks like manufacturers use the same pressure sensor across their lineups: all iPhones 0.8Hz, all Samsungs 5.6Hz, all Nexuses 30Hz... I wonder if LG uses the same 75Hz pressure sensor in their phones as in their watch?

Smart Altimeter has been updated to version 1.0.4 for Android and Wear devices.

It is also updated for Wear 2.0, so the app can be downloaded from the watch's app store (and thus should be available even if the watch is paired to an iphone).

Release notes:

- fixed unintended 2s lag due to excessive smoothing; the lag on devices with fast barometers should not exceed 0.1s now or 12 samples, whichever is greater
- increased frame rate of screen updates to 15fps (up from 6fps)
- changed number formatting of altitude to resemble skydiving altimeters: altitude is rounded to 10 units if below 1000 units; displayed in thousands with 2 decimals if above 1000 units
- removed Butterworth and Savitzky-Golay smoothing filters as altitude smoothing layers (with only Low Pass filter remaining) for now to resolve issues with sudden altitude spikes
- reduced jitter in vertical speed by limiting it to values above 1 unit and by removing Butterworth and Savitzky-Golay filters (with only Savitzky-Golay filter for altitude used as a smoothing differentiator to obtain speed, and Low Pass filter for speed remaining)
- added raw altitude AMSL output, for observing sensor sensitivity and accuracy
- fixed a bug where the measured barometer sample rate would multiply if the app is placed in background and entered again

I would be grateful for any feedback on this new version, since the next time I jump will be probably in a few weeks. (and no, I'm not suggesting BASE jumping while looking at an altimeter - just general use in the mountains, as well as a quick glance at opening altitude on "staple" jumps like Brento, Lauterbrunnen, etc.) Comparison to GPS would be great, especially when compared to other, well-established digital altimeters.

I'm still stocked about this amazing hardware that fits a real nanocomputer in a wristwatch form factor. Here's a teardown of a 4-year old LG G Watch R:




(from https://www.onethesis.com/...lg-watch-r-teardown/)

It has an Alps electric Digital Pressure Sensor, outputting 90 pressure samples per second.



I don't know what type of pressure sensor Nixon Mission uses, but if closeness of its sample interval (6ms) to popular Bosch BMP280 (5.5ms) is any indication, it might be using Bosch.

We live in amazing times, and the best is yet to come! (I hear rumors of imminent release this Fall of a new Quallcomm Snapdragon 3100 SoC for smartwatches with more power and better battery life for always-on screens.)