GA Tech Students Use Cell Phone Pings To Find Missing Person (ajc.com)

McGruber writes: Georgia Authorities are giving kudos to technology – and the perseverance of Georgia Tech students – for the safe return of a fellow student who disappeared after a Friday night party. The missing student was found Monday morning along railroad tracks, in northeast Atlanta. He had been beaten, was unconscious and was taken to Grady Memorial Hospital. Georgia Tech Police Chief Robert Connolly said "The students rallied together and then they started searching. The students stayed out until midnight last night, putting out pamphlets and combing the area, anywhere they could possibly find [cell phone] pings along the route." The students "were not going to stop. They checked every hospital, every hotel, they checked everywhere. They didn't give up on their friend."

Comments

SAR

[Citizen of Earth]

Search And Rescue teams should carry "Stingray" mobile cell towers with them to locate missing persons in the wilderness. Any phone in range would try to connect with them.

Re:SAR

[barc0001]

I had that idea years ago. They could mount one in a chopper and once they get a ping, crank down the range to quickly narrow the search. But of course we wouldn't want to use Stingrays for saving lives when they're much more useful for spying on everyone.

Re:SAR

[ShanghaiBill]

But of course we wouldn't want to use Stingrays for saving lives when they're much more useful for spying on everyone.

Those two uses are not mutually exclusive. In fact, the former facilitates the latter. Law enforcement can justify the procurement and deployment of a Stingray for search and rescue, and then use it for spying on the boyfriend of their ex-wife when there is no SAR in progress. They could use the same argument to justify the drone it is mounted on.

Re:SAR

[Fire_Wraith]

Better to use the technology for good, than for evil.

Re:SAR

[schnell]

I had that idea years ago. They could mount one in a chopper and once they get a ping, crank down the range to quickly narrow the search.

That's almost entirely unnecessary (and this article is almost total crap).

If your cellphone is turned on (and not out of battery), and within range of a cell tower, your provider will know about it. Your phone "checks in" every so often to make sure calls to it are being routed to the correct tower. Police can lawfully, with a warrant, subpoena this information from your provider, no Stingray required. If for some reason your phone was on but outside the range of any cell towers, your idea might make some sense. But in that case it wouldn't need to be a Stingray per se; a portable cell tower (like providers deploy for disasters/emergencies) would do the trick just the same.

Oh, and while I'm at it, college students have no way to access the information of cell phones pinging providers' cell towers. The closest you could reasonably get is if they have each others' iPhone "Find My Friends" or Android equivalent, which would actually pull a full GPS location off the phone. But that is available to every jackass in the world you choose to share your location with, no engineering prowess or ingenuity involved. And it has nothing to do with "tower pings."

TL/DR; Stingrays not necessary. College students have no legal access to the cellphone tower "ping" information and shouldn't. Slashdot editors should consider actually, you know, editing story submissions into being cogent rather than clickbait.

what is a "cell phone ping"?

[YesIAmAScript]

And how does it reveal your location?

Does this mean some kind of peer-to-peer WiFi or Bluetooth? I don't understand.

If it's cellular, then the phone is either reachable or it isn't, that doesn't change based upon how near you are to the other phone.

Are they saying they just used a built-in location service to find it?

Re:what is a "cell phone ping"?

[lakeland]

Pinging a cellphone means setting up a portable cellphone tower. All cellphones within range will report their existence to you, which you can then cross reference against your missing person's IMEI number...Through triangulation/multiple different towers you can work out the location quite accurately.

Of course this is not generally available to the public. For a start you need to have a portable tower (or borrow a few from a local telco) and secondly you'll need to cross-reference his phone number to look up his IMEI.

I'm curious how a bunch of students were able to get past the two restrictions - I can imagine a uni having some portable towers lying around for research purposes, but how would they have found out his IMEI number?

Re:what is a "cell phone ping"?

[Wycliffe]

I'm curious how a bunch of students were able to get past the two restrictions - I can imagine a uni having some portable towers lying around for research purposes, but how would they have found out his IMEI number?

From the article (hiding in the header), I don't think that they did. It sounds like the police gave the students the last known cell phone towers and they canvased the area on foot around those towers.

Re:what is a "cell phone ping"?

[Obfuscant]

Pinging a cellphone means setting up a portable cellphone tower.

No, pinging a cellphone doesn't mean setting up a portable cellphone tower. "Pinging" is the what the cellphone companies call the process a cellphone goes through trying to register with any available cellphone tower (almost always fixed). It's an analogy for the "ping" command in unix.

There are established procedures for public safety agencies to request and obtain the cellphone data. All it takes is a signed affidavit attesting that the data is necessary for safety of life -- which this clearly was. One of the first questions in the lost person interview is "does he own a cellphone and what's the number?"

With one cell tower hearing the ping, you can get a direction (from the phased array antennas they use on a tower) and an approximate distance (from the signal strength.) Both are recorded for every ping.

From two or more towers you can use either triangulation (multiple bearings to the same ping) or time-of-arrival differences to measure the relative distances. (The latter is the basis for GPS.)

I've been involved with searches where the ping has resulted in locating the subject within a few hundred yards. One such search didn't result in a find right away because the subjects were trying to hide and heard the aircraft that was looking for them. They came out a few days later when they got hungry.

Re:RTFM!

[JimMcc]

Yes, because it's much too difficult to actually put the link to the story in the fine summary. They've tried it for 15+ years and it's been obvious that the technique didn't work so we need to come up with something new. Something edgy, like making the link obscure.

Oh, for those that are reading challenged, the above was sarcasm.

Cell Phone Pings

[YrWrstNtmr]

The actual article, once you freaking find it, has a one liner about "Cellphone records showed he was possibly in the area of DeKalb Avenue a couple of hours later." After that, it was just people walking around searching.

How the hell is this 'cell phone pings'? I was expecting some uber geeky geolocation doodad written in an overnight Cheeto induced haze. (no, not THAT "uber")
What, his phone did the auto check-in thing via some standard 'app'?

Hmmm

[John Jorsett]

There's some significant holes in this story. According to the ajc.com article, he had last been seen 11pm Friday. Friends started looking for him "last night," presumably Sunday based on the article's date of Monday, Oct 19. That means he would have been lying unconscious for up to two days, yet later in the article we read, 'Atlanta police Lt. Charles Hampton described Hubert’s injuries as minor, adding that he was “not sure where those injuries came from.”' Also, what are these pings they're talking about? Pings like when the cops have the phone company tell them which towers his phone is hitting? Were the cops relaying that info to student searchers instead of searching themselves? It sounds like something else: "The students stayed out until midnight last night, putting out pamphlets and combing the area, anywhere they could possibly find [cell phone] pings along the route.” How do civilian student searchers "find pings"? I wish journalism wasn't such a realm of technical illiterates.