Posted by nizarmah 4/1/2025
First responders have awesome tools. But in tough situations, even common folks need to help.
After what happened in Myanmar, we need something like this that works properly.
It has only been tested in controlled environments. It can also be improved; I know BLE is not _that_ effective under rubble.
If you have any feedback or can contribute, don't hold back.
Can voice be transferred? Message be recorded and rebroadcasted?
What about making the device vibrate SOS pulses. The person at stake might not have the strength to tap or bang, may be able put the phone on a metallic surface and send vibrations?
Those two questions are spot on.
Voice cannot be transferred yet. Re-broadcasting might require a bluetooth meshnet.
Vibrations are a great idea. They are not that battery intensive. They also can be detected by 3rd party tech.
Both were added to the list of ideas. Thank you!!
I haven't done any effort there, because I want to get this into hands.
Improvements are definitely needed with location, but the signal loss as you mentioned is higher priority and restricts what can be used for location.
I'm planning to do my homework about alternatives to help mitigate the signal loss. And from there, the options for location might be clearer.
In my situation, GPS was being jammed. That made GPS not useful at all. I tried my best to avoid it for that and battery usage.
But this initial reading and turning it off is just genius. I added to the list. Thank you so much!
This is a bit more extreme, but some type of triangulation from multiple rescuers could be useful in closing in on a spot.
This is really interesting and thanks for sharing.
Ideal conditions is likely open spaces with no interference. Walls and concrete lower that as you mentioned.
I'm hoping it can help if people are standing right next to the rubble, whether BLE or the "siren" sound.
I have no guarantees though. I haven't properly tested because I haven't thought of a low cost option yet.
I don't know if phones support LE Long Range. I will look into it [1]. Thank you!!
Some of them might require you open the application the first time ever while on internet.
There are many out there (on the App/Play store) that support both use cases you mentioned, I just can't list any off the top of my head because it's been a while since I used one.
WiFi doesn't fare any better than BLE under rubble unfortunately, but WiFi is going to be a useful technology to build disaster response tools in general
I'm not a fan of how Apple managed to make background BLE advertising and scanning work only with its own devices.
Would be nice if the readme included the current method to detect disaster and the nature of the "SOS" signal. Is that something Bluetooth has a behaved protocol for, or is it really just chirping?
+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!!
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.
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.
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.
I don't know the amount of battery that is necessary to do that.
To cut time, I didn't modify the volume programmatically. So the user would need to have their volume set at 100%.
This needs improvement, especially considering my phone is always muted.
Likewise, the battery usage needs better testing.
It of course depends on the disaster, but in case of war this app can be used to find survivors for purposes other than saving them.
Great idea though.
It'll be easy to find a collapsed building site. The person rescuing just needs to be close to the site with the app. Otherwise, the signal might not be noticed.
+1 regarding finding survivors for malicious purposes. I tried my best to lower the surface area of that happening. It's still possible in edge cases, like opposing soldiers finding the people transmitting SOS, but they need to be extremely close to do that.