RESQ Hunts For Lost Hikers From The Air

When lost hiking out in the back country, a cell phone might not seem like the most useful tool. Absent a signal from the cellular network, it’s not possible to make outgoing calls for help. However, carrying your phone may just make it a lot easier for rescuers to find you, and [Eric] is making a tool to do the job.

The handheld version of ResQ features a directional Yagi antenna to help pinpoint the location of the signal.

[Eric]’s project is named ResQ, and aims to find lost hikers by detecting the beacon packets from a cellphone’s WiFi adapter. The project comes in two forms; a handheld unit with a directional Yagi antenna, and a drone-mounted unit that can overfly terrain to scan for signals.

ResQ is built around the ESP8266, which is a cheap and accessible way to build a custom WiFI scanner. Currently, the system is able to detect WiFi devices and log MAC addresses along with timestamps and GPS location data to an SD card to help rescuers locate lost individuals. Future plans involve adding a live downlink to the drone such that any pings can be reported live for rescuers to investigate.

Similar systems exist commercially, primarily working with cell signals rather than WiFi. Costs are prohibitively high for many organisations though, so we can see ResQ filling in gaps as a useful tool to have. We’ve featured other radio gear for search and rescue before, too. Video after the break.


23 thoughts on “RESQ Hunts For Lost Hikers From The Air

  1. This is a novel idea to help those stranded in the wild. But thinking from a hiker’s point of view. If I have a phone with power and getting no signal, I would put it in Airplane Mode to conserve energy. Since a phone is still useful for GPS or as a backup flashlight. Even a fully charged smartphone won’t last 24 hours constantly trying to lock a weak signal. On the other hand, carriers may have some information where a phone was last registered. That will help narrow down the search.

    1. True, I usually put my phone into airplane mode, or low power mapping mode or shut it off completely except when I need to get a GPS fix. As for using it as a backup flashlight – wot you don’t carry a spare headlamp? Might as well also use it to take lots of nice holiday photos while you’re at it. The trick is to not only climb mountains but to pay enough attention to get back down alive, or so I’ve been told.

  2. That what most people would do though consider if you know the area is equipped with such a tracking as in the article. If you do not return by the agreed time you registered before the hike then you would know to keep your wifi on.

    1. Not outlawed, regulated! You are free to help people, but permission from the government to help people will cost you. I think I would rather die alone and starving than to think that someone without an FAA part 107 license, using an unregistered UAV, with equipment not certified with the FCC, would be endangering commercial air-traffic or the RF spectrum. And you should too comrade!

      1. so do you also think people needing pilot licenses to take part in search and rescue is stupid too. or you just taking part in the great American past time of of screaming like a whinny brat because someone told you had to play but … RULES!

        honestly small minded fools like you make me sick.

        1. Obvious hyperbole is obvious. But the FAA is 100% power grabbing over hobby level UAVs.

          I take it that you are perfectly fine with the FAA requiring certification for ANY commercial UAV applications, and registration of hobbyist level RC devices, meanwhile allowing Boeing to self-certify a plane that literally nose dives into the ground. Do you make a few pennies with your drone footage from monetized youtube videos? better have your Part 107 certificate and UAV registration. Since you hold the rules in such high regard.

          I’m perfectly happy to require registration of something that would exceed an ultralight (254 lb) but a toy that weighs more than 0.5 lb is ridiculous. If it can carry a human, no big deal, have fun! (FAA part 103) If it is RC, OMG we need regulations!!

          Honestly, someone that can’t see the difference between actually flying an airplane that people are on and playing with a Styrofoam toy make me sick.

      2. Where I live not all drones have to be registered, nor their pilots licenced… If throne dont excess 800g.

        And playing with ESPs is not regulated, AFAIK ESPs are compliant with all RF regulation in EU. Imay be wrong, but i get used to believe it :)

        My $0.02I would not be as sharp as dexdrako, but let me feel you somewhat over-reacted…
        NB: ok OP comment was about US, but, meh…

    1. Pose as a buyer…
      You: “Hey, I was thinking of buying 10,000 of your Yagi antennas for my high end electronics chain, but what is the dB gain of them.”
      They: “What gain do you want printed on box?”

  3. Is this detecting the “beacon” frames (AP) or “probe” frames (client)?

    A phone is more likely to broadcast probe frames than beacon frames. Probe frames can provide unique information so users can be filtered.

    If the phone is not transmitting probe frames (they usually do if wifi is turned on, even if they are connected/unconnected to an AP but it might not if the battery is low or the network congested), then the interrogator could create an open AP to see if the phone will “bite”.

    The ESP32 also can track bluetooth frames and similar methods used to detect phones with their bluetooth enable.

    1. The airframe is irrelevant; you wouldn’t be doing a real S&R run with it, but it would be perfectly fine for developing the detector with. Other people are working on other parts of a full solution, and bringing them together is what events like the UAV Challenge are for.

      1. If only we could work out how large birds detect and utilise thermals, then you’d have the ability to fly a glider for the entire day. I live in a region where we see a lot of wedge-tailed eagles and they often travel in groups in directions that are different to the one the thermals are drifting, yet they hardly move their wings the entire time. They gain height in one thermal then glide in the direction they want until they detect another thermal and then repeat the exercise.

  4. just a hint, your antennas seem to be a lot heavier than they need to be. I’ve done a lot of work on thin film antenna systems. Once your conductors are much thicker than 3 x sigma you’re not buying all that much in terms of antenna performance. This is an interesting idea, I’m a backcountry outdoors leader and 40 year electronics/electromagnetics engineer and also have been wondering if there are ways of helping search and rescue organizations with better technology.

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