Detecting a cell phone for Search and Rescue

[Caroline Rose]

Makers, 

I'm involved with a national working group for Geographic Information Systems (GIS) for Wilderness Search and Rescue. Some other members of this committee are writing a handbook about the use of cell phone data for Search and Rescue. 

These handbook authors are trying to research possibilities for locating a lost person by way of locating their cell phone, and have asked me to tap into the knowledge base of makers. 

Here's how one author described the problem:

 "Many of these remote areas [e.g., parts of Colorado Rockies or the Sierra Nevada] are in cell dead zones so [we are] unable to use tower data... in most of these scenarios, there wouldn't be another phone in the immediate area (searchers could turn theirs off), so it's not necessary to emulate a cell tower, only passively detect a cell signal, direction and range (distance)." 

Many Wilderness Search and Rescue teams are volunteer organizations, without the resources (financially, human resources, technical training-wise) that law enforcement agencies have. He explains that while law enforcement may have access to a Stingray or IMSI detector, by the time a Search and Rescue mission gets ahold of one, the cell battery has often died.  

"There's commercial products from, for instance, Berkeley Varitroncs Systems but they're pretty expensive and not designed for search and rescue... We need something that can be tested in real world conditions and developed to meet SAR needs and that can be quickly deployed without security or warrant concerns. I've talked to BVS, but they don't seem interested in a demo and they're too expensive for any SAR team to experiment with."

They are asking for suggestions: possible directions one might explore to build a device which...

• detects a cell signal, direction and range
• is portable
• operates in an area with no connection to cell towers
• doesn't present security or warrant concerns
• is inexpensive

that a (technically savvy) Search and Rescue volunteer might potentially build, test, and deploy. 

 

I would really appreciate any suggestions that you can pass on to them. 

Email or find me at the Iron Pour this weekend!

Thank you! 

Caroline Rose 

cmr....@gmail.com 

[Davi P]

You may need to emulate a cell tower to some extent to get the phone to transmit a signal, preferably at its maximum power. Hope you can find a cell engineer to talk to.

https://en.wikipedia.org/wiki/IMSI-catcher

https://en.wikipedia.org/wiki/Stingray_phone_tracker

--Davi

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[Jeff Whitehouse]

What you are thinking about has been done on the cheap* for a number of years. Take a look at this article http://geeknizer.com/diy-drone-plane-hack-wifi-phone-calls/ . This was posted in August 2011, so I'm guessing the cost of parts will of come down. 

*6k is cheap by S&R standards.

On Thu, Feb 4, 2016 at 11:37 AM, Caroline Rose <cmr....@gmail.com> wrote:

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[FStanton]

Although their product line doesn't have anything which appears able to detect a cell phone (they use the Iridium satellite), they may have technical expertise which could lead you in the right direction: http://www.delorme.com.

F.

[D.J. Nephew]

I was just coming to share the link Jeff did.   I am a member of the Mesa County SAR in Colorado and a licensed HAM (WO9N), and this has been on my mind a bit.

There are a number of facets to the problem, but the big one in my mind is that the terrain is so rugged and steep.  It is not at all unusual for me to push a full 5W at 2m and not be able to reach someone just over the next ridge - and that condition is even worse at the higher frequencies and lower power output of cell phones.  If someone is down a canyon or ravine, even with a really good receiver, we could be right on top of them and never hear the cell.

So, while a man portable device would be handy, it would really have to be aerial to be truly effective.  Either a Drone, or usable from a chopper - but the advantage of getting over the terrain cannot be overstated.

This is backed up by experience - we've had a number of recoveries where the subject was using FRS/GMRS radios and totally unreachable from the ground some short distance away, but easily picked up by the chopper miles off.

If you wouldn't mind sharing what resources and other things you've found, I'd appreciate it - I've been slowly building a parts list and plans for doing a drone based IMSI detector for just this sort of thing.

-- D.J.