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Comment by nizarmah | Hacker News Reader

1. Disaster detection is a user toggle-able option that uses motion sensors to detect extreme shifts. 2. SOS signal is a BLE broadcast along with an alarm-like audio (generated from a sine wave).

+1, I usually have it off, but toggle it on when I'm in a bad setting. It can be made more accurate with time, especially with onboard ML models.

It is a Bluetooth protocol (BLE Scanning and Advertising, if you'd like to learn more about it).

I'll be sure to update the readme. Thank you for the great questions!!

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It would be interesting to see if some of the earthquake advanced warning notifications could be integrated too. at least then it would be an "official" warning. seems like false positives would be possible with the device's motion sensors even with an "i'm okay" type of cancel.

I LOVE this. Thank you! Huge +1, even though it's not going to be easy.

Yeah, false positives are the largest problem. The barometer sensor helps reduce them, but it's not available on all phones.

Machine learning can help a lot here, but I haven't looked for publicly available data yet.

Excellent! Good to know it uses the standard BLE advertisement for the SOS and doesn't need WiFi or GPS.

Well thought out. Excellent work. Thank you for making this available as open source!

Side note -- I wonder if it's possible to have a companion system to scan regularly for the signal at home for the elderly. Then notify caregivers from the companion using available wifi/cell if the SOS is detected. Since it's so well behaved it seems like even having a regular wellness check mode would be possible. Having a companion system for relay would allow the app itself to never need WiFi/cell and have independent care notifications protocols that wouldn't need to be maintained in the app.

Thanks a lot for the kind words!

That's a really cool idea. Kudos!! A companion system should be relatively easy. It's also two single devices communicating with each other which makes things much simpler to build as well. This is worth looking closer into.

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