ResQ Search and Rescue Tools

Air OR ground-based tools to detect people by using their existing cell phone signature

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This open source project investigates using AP beacon packet sniffing to locate people such as lost hikers, campers and even poachers in game preserves. This works anywhere- as long as wifi is enabled on the targets phone. The hardware detects the beacon frames from their cellular phone, records the GPS coordinates for use later. 2 flavors are made: one hand-held portable and the other airborne carried by plane or drone.


I was inspired by the constant stream of search and rescue operations on the television show "North Woods Law". Each week they struggled to find lost people in the remote/rugged areas of Maine U.S.A. These areas often have no cellular service but in almost every case the target people had cellphones on them and working. As I live in Canada- we have a surplus of these situations in our vast wilderness as well.  I theorized I could use an external 2.4GHz antenna to receive the AP beacon frames from those phones ad capture that data. 

This hardware can be embedded in to any very small drone or RC aircraft. It can also be attached to existing manned aircraft already participating in the search. 

Using small drone aircraft (like the Nano Talon I use here) gives all the advantages such as flight condition tolerance, height, terrain, time of day etc that drones have over manned aircraft. They can also be sent on the full way-point mission without human intervention and tracked live from any ground station. 

What it does (both air unit and ground unit W yagi):

  • Detects all Beacons and their mac addresses within range
  • Detects All AP's in range (not needed but why not log them anyhow)
  • Gets GPS Lat/Long positioning
  • Gets GPS UTC Time
  • Logs all the above to the SD card .csv file every time any device detected changes
  • Displays the number of clients detected, APs detected, time and Lat/Long on the OLED screen live. 
  • Air unit will eventually send telemetry to ground control for live alerts (likely using existing 433MHz telemetry already sending flight data)


I started this build in 2018 and have proven out the Nano Talon airrframe to be a very worthy commercial candidate with good payload and HUGE flight times while operating fully autonomously. The Nano Talon breaks down small for easy transport/storage.

So far I am using the Wedmos D1 mini PRO with an external antenna (YAGI or Rubber duck) to receive the beacon frames, log them to SD Card with RSSI values (adds more precise direction finding if you fly a grid pattern) to review the MAC address list as well as plot with Google Earth/maps. I can easily transmit this via LORA or NRF module to the ground instantly as well. This will be logged as a separate version of the hardware.

I will update this and post the videos as we move forward with publishing (this will take me some time to document properly)


Full build overview video coming soon. 

See YT playlist for existing tutorials in the links (I documented most facets of the build in standalone related videos which when all combines- make this project) Handy eh?

Stay tuned for updates

  • 1 × Full BOM maintained in Github Repo (Updated and links to parts)
  • 1 × Wemos D1 Mini Pro ESP8266
  • 1 × SPI SD Card Reader/Card
  • 1 × 0.96" OLED Display
  • 1 × 2.4 GHz Yagi Antenna

View all 9 components

  • PCBs Have Landed

    Eric Wiiliama day ago 0 comments

    Well the PCBs have arrived in fine form from PCBWay.  Full disclosure- They support my YouTube videos by sponsoring orders like this (which is totally awesome). I placed the order like anyone else though and it was nothing special- just the $5 deal with black boards selected.  I have purchased boards from them several times and always found them to be excellent.

    Since I will have plenty of spare boards I can definitely try to give a bunch of these away to anyone who wants one to build this project themselves. Just need you to cover postage. Hit me up if you would like one.  Free to me- Free to you :)

    Thanks to Brian Lough's awesome panelising YouTube video these came out great!  I got right to work assembling the first air unit prototype

    I am a bit short on SD modules and GPS units so I was a bit worried but turns out- I seem to have routed them correctly.  Yay for luck. 

    Since I have now decided to put the OLED in to the air unit as well as the ground I need to make a new enclosure design.  No problem that Fusion 360 and my 3D printer cant fix. 

    I am putting the GPS module inside the enclosure as well just to keep things clean. It can be routed outside if needed but I think in most cases it should be just fine.  These BN220s get a GPS fix even in my basement at times so it should be fine in most orientations on any aircraft. 

  • PCB Created (Hopefully)

    Eric Wiiliam3 days ago 0 comments

    I finally made time to do the schematic layout and custom PCB.  It is pretty basic but that did not stop me from doing an absolutely horrible job in Fritzing

    No matter- it allowed me to lay out the board and do a quick PCB layout which should hopefully work :)

    I panelized them using an open source panelizing tool I found from a Brian Lough video:


    I sent them off to PCBWay for fabrication and fingers crossed- I should have about 60 boards YAY!  If they work (might take a miracle knowing my luck lately) I will try to give a bunch away to anyone who wishes to make this project.  They could actually be used for ANY ESP project where you want to have an SD card, OLED, GPS or combination thereof.

    All files, layouts, Gerbers etc are in the GitHub Repo. 


  • RF Craziness! (Antenna Testing)

    Eric Wiiliam07/26/2020 at 12:24 0 comments

    This week my new VNA arrived which goes up to ~3 GHz enabling me to finally start testing/optimizing antennas.  Although initial testing seemed to working with my existing antennas I suspect with fully optimized/tuned antennas the results will be even better. 

    Yagi's and Rubber-duck dipoles all ready:

    This Nano VNA seems to work great. I will do some tests on lower freq antennas to compare it to my existing VNA which only goes up to ~1 GHz. Since I dont have crazy expensive lab equipment I've learned to make do by cross referencing multiple lower end tools.  Everything I read online points to these VNAs working just GREAT for this purpose though.  Here is a quick measure across a large portion of the spectrum- you can see the SWR isnt perfect but totally acceptable at 2.4:

    Zooming in at our target and calibrating gives a better indication (picture missing)

    Testing against some larger (somewhat higher gain) router antennas

    I'm pretty happy now that I can work with the antennas properly and I'm finally learning a lot more about RF which is why I do these projects in the first place.  Fun

  • GPS Integration SUCCESS!

    Eric Wiiliam07/24/2020 at 13:39 0 comments

    Last night was a big win for me. I was able to integrate the GPS code in to the existing logging code and it works :) All is pushed to GIT and I even released it as an Alpha so others can use it right away. 

    I will be using the same codebase and schematic files for BOTH the air and ground based units.  The only difference will be that I will likely omit the OLED display on the air unit to save weight.  I may add battery and voltage regulators later but for now I will keep them external as it is much easier and the planes already have Vref supply on board. 

    Right now it:

    • Detects all Beacons and their mac addresses within range
    • Detects All AP's in range
    • Gets GPS Lat/Long positioning
    • Gets GPS UTC Time
    • Logs all the above to the SD card .csv file every time any device detected changes
    • Displays the number of clients detected, APs detected, time and Lat/Long on the OLED screen live. 


    I actually didnt think I would get this far.  It works great and although not as good as sniffing the cellular data packets- this indeed works for a budget price of just a few bucks.  Next I think I will try testing out the UAV/Drone autonomous flight modes this weekend if the weather is good. Then more work on the schematic files and a custom PCB I think. 


  • Air Unit Enclosure Added

    Eric Wiiliam07/13/2020 at 21:41 0 comments

    I needed to get the air unit sorted for the airborne hardware (the ground unit is a lot easier/simpler) so I decided to sort out the enclosure and test fit it this weekend. 

    Here is the first test version inside the payload bay of the Nano Talon:

    The CAD file originated from Thingiverse and the links are in my GitHub repo.  The Thingiverse customizer seems to be broken so I downloaded OpenScad and tried my own dimensions:

    I was pretty amazed at how easy OpenScad was to work with (small files too). Opened up CURA and sliced/printed on my i3 Mega with no issues

    All this will be included in the overview video coming soon.  I may need to resize the enclosure once I test the GPS unit (I really want try try to keep the GPS inside the case but probably need to run it to the top of the aircraft).  


  • Air Unit Testing

    Eric Wiiliam07/10/2020 at 20:29 0 comments

    Since I will be doing the ground YAGI and an air-unit version I spent some time testing the UAV to carry the payload. 

    The Nano Talon is still my aircraft of choice here and I've finally made some time to properly finish setting up the autopilot and antonymous modes.  Last night I took a quick tuning flight with the air unit in the belly storage (no ground communication from the ESP-82666 though).

    Setup video:

    The aircraft is broadcasting two telemetry downlinks in this test. One is my ~900MHZ control link which has full telemetry of all aircraft signals back to my radio and a second which allows monitoring and control via 433MHZ.  Both worked perfectly.  You can see the thunder storms building around me as I performed an auto trim cycle which centers the control surfaces for my new payload in flight.

    Full DVR video:

    Ultimately my video downlink failed and I have ordered a new diversity receiver module for my goggles as well as dropped the power output down on the VTX as it has been overheating in this >34C heat lately.  The new video receiver will be here next week and should work better in all conditions since it will now "stitch" together the two video feeds from my patch and my omin-directional antennas in to one much cleaner video.  Happy days. 

    I have been working on the handheld unit as well so update on that soon. I was able to get the logging working properly and GPS also tested.  So far- it seems like I should be able to finish it up soon. 

    Just need to make a case for the air unit and decide if I want to do live telemetry via LORA radio or just store the data on the SD card on the aircraft.  Lots of options here where I can even link multiple receivers or do more crazy stuff.  

    Fist step is to finish the code...

  • Files Added

    Eric Wiiliam06/04/2020 at 18:34 0 comments

    I added the CAD files and links for a 3D printable enclosure to the GitHub repo. This is a larger project box for use with the breadboard testing variant. The final version for proper PCB will come later but some may wish to have theirs on a breadboard so this will probably be handy in the future 

    The files are customized from another Thingiverse design you can find in the links/attribution. You can use the website customizer to change the design to suit your design for any changes needed.

  • GPS Finally Working...Again

    Eric Wiiliam06/03/2020 at 01:04 0 comments

    What I thought would be an easy GPS re-integration was anything but. I had this working fine in the past when I originally tested this code as the ResQ-Air version inside my plane but there have now  been changes in the ESP board libraries/software serial (seemingly to support ESP32) which broke all the functionality for me so that serial was impossible. 

    Updating the GPS libraries and board defs )added to my repo as well for future ref) finally got it compiling but the pins 3 and 4 dont work directly for the D1 mini and need to be swapped for their true numbering of 0 and 2. Apparently I had forgotten this since last year...

    The BN220 is working at 9600 baud (default it ships with) on the pins discussed. I put 2 example sketches in my GitHub repo so anyone else can test theirs too if they need to troubleshoot without the OLED and SD card. 

    Now to integrate all the code together which I have never done before (with OLED).  If push comes to shove I can omit the OLED entirely and just log to SD only or slap on a bluetooth module and just connect that to serial to use your phone or tablet as the interface.  Handy. 

    Winning :)

  • Code Uploaded/Updated

    Eric Wiiliam06/02/2020 at 20:05 0 comments

    All current code is now moved to GIT. It's open source now :)  

    On the weekend I went out and did some range tests with the YAGI- there were so many people even in my remote area that it just spammed me with MAC addresses.  I good problem to have I suppose :) 

    I ran in to some issues with the OLED and found I could NOT make the I2C display work at the same time as writing to the SD card via SPI.  No matter what I tried it seemed to not work. Eventually I guessed that it was a RAM issue and not a strange hardware glitch so I moved over to the lightest display library I could find (instead of the Adafruit one) and it now works!

    I also got some neat comments pointing out that this may work quite well on game preserves to catch/track poachers. I see no reason it wouldn't as long as they are carrying a phone without wifi turned off. I suppose most do. 

    Neat idea anyhow.  

  • YouTube Playlist Created

    Eric Wiiliam05/31/2020 at 15:09 0 comments

    I have created a dedicated playslist for the ResQ project here:

    All the clever viewers that deduced that all the drone and ESP8266 projects were related- You were right :)  The playlist starts from the beginning of the Nano Talon build and covers it right until the end including the telemetry data so anyone, anywhere should be able to build this EXACT airframe to carry the ResQ if they like. 

    Tutorials on the Wemos antenna mod and SD card wiring also included- as you all suspected they are indeed in order so others can make this entire project :)  

    Videos and instruction upcoming on the final assembly of the ResQ and the different versions of it (standalone and live data at this time) stay tuned. 

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Andrei wrote 07/29/2020 at 13:48 point

we have 99% cell network coverage in our country. how it will work here? maybe directional antenna can be used? 

  Are you sure? yes | no

ris wrote 07/10/2020 at 23:45 point

My guess is you'd get even better results if you listened for signals on the cell frequencies. The phones may be out of range but they'll still be probing at full power for a cell station.

  Are you sure? yes | no

Eric Wiiliam wrote 07/13/2020 at 20:43 point

Surely but that would require a specialty radio that I do not have I'm afraid. Hence 2.4

  Are you sure? yes | no

ris wrote 07/13/2020 at 21:15 point

You could do it with a low-end SDR.

  Are you sure? yes | no

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