
Engineers Say They've Created a Way to Detect Bombs and Guns Using Basic Wifi - kiyanwang
https://gizmodo.com/a-group-of-engineers-say-theyve-created-a-way-to-detect-1828361739
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Animats
The paper [1] is interesting, although they spend too much space writing about
the purported benefits. The concept here is to exploit WiFi gear's usages of
many different frequencies. Measuring the amplitude and phase shift on each
channel provides some info about what each channel bounced off of and
diffracted around.

Inevitably, they then dump all the data into a neural net. They trained on
about 15 objects, which is a reasonable start. They didn't go on to testing
with enough objects to be useful. "The results show that our system can detect
over 95% dangerous objects in different types of bags and successfully
identify 90% dangerous material types." By "dangerous" they just mean metal or
liquid. It's not like they can tell a gun from a soup can.

[1]
[http://www.winlab.rutgers.edu/~yychen/papers/Towards%20In%20...](http://www.winlab.rutgers.edu/~yychen/papers/Towards%20In%20baggage%20Suspicious%20Object%20Detection%20Using%20Commodity%20WiFi.pdf)

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fake-name
> The concept here is to exploit WiFi gear's usages of many different
> frequencies. Measuring the amplitude and phase shift on each channel
> provides some info about what each channel bounced off of and diffracted
> around.

This exists. They're just reimplemented non-cooperative SFCW radar. It's not
new.

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abeppu
It seems like they can detect liquid and metal, which is very different from
detecting bombs and guns. That's like building a face detection library and
saying you can find terrorists. If mostly you just identify people with water
bottles or laptops, what problem would this really solve?

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JoeAltmaier
Pattern recognition of common bomb and gun configurations? Or better, any non-
standard configuration.

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jandrese
That might be able to detect something like a hand grenade (but honestly I'm
dubious), but finding "non-standard configurations" seems like it requires a
full up strong AI. It has to be able to look at a jumble of components in a
configuration it has never seen before and recognize that it is a bomb. This
is hard problem for humans and hits on several hard aspects of AI at once.

~~~
JoeAltmaier
Or just recognize it as not-a-bomb. Easier - e.g. the set of metal things
normally in luggage may be small

~~~
jandrese
Bombs aren't necessarily made out of metal.

~~~
killjoywashere
The fusing wires almost certainly are, unless you're dealing with a nation-
state or, possibly, a major corporation.

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foxyv
Unless you just use a fuse, Looney Toons/Shoe Bomber style.

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nixpulvis
Can't wait to see the day police show up at peoples houses because an opaque
AI/ML/Statistical-thingy said they were creating bombs, when in fact it was a
loaf of bread (or whatever). Minority report gets more and more real.

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astrodust
99% accuracy sounds impressive until you realize this thing will flag 1% of
_all objects_ as potentially threatening.

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sigfubar
And of course it'll entirely miss the 2,600 rounds of ammo in my apartment.

~~~
astrodust
And the box of tannerite, and the separate containers of powdered iron and
aluminum...

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_Microft
Paper (PDF):
[http://www.winlab.rutgers.edu/~yychen/papers/Towards%20In%20...](http://www.winlab.rutgers.edu/~yychen/papers/Towards%20In%20baggage%20Suspicious%20Object%20Detection%20Using%20Commodity%20WiFi.pdf)

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pluma
My first reading of that headline was that "bombs" means unexploded ordnance
(which is a regular problem for construction projects in my home town thanks
to WW2 air raids). I'm not sure if this means I'm sheltered or level-headed.

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fcarraldo
Another take on this paper would read, “Engineeers have created a way to
weaponize Wi-Fi signals for invisible and invasive surveillance”.

This turns consumer level tech into a militant authoritarian’s dream. Have
they also developed ways to identify when this technology is being used
surreptitiously?

~~~
Isomatik
This method appears to just measure the Tx and Rx paths on an off-the-shelf
modem, so you'd have to physically check the router, or I'm sure this could be
handled in firmware. They're measuring phase and amplitude differences from
unmodified traffic on 2.4GHz so you can't detect it as an outsider.

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bjt2n3904
My cynical post script to the title, without reading the article: "in a
laboratory setting".

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rm_-rf_slash
Agreed. When this method is applied in, say, Germany, to safely detect WWII
ordinance, then it will have proven itself.

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kqr2
Reminds me of _Wi-Vi: See Through Walls with Wi-Fi Signals_ from 2013:

[http://people.csail.mit.edu/fadel/wivi/](http://people.csail.mit.edu/fadel/wivi/)

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akshayB
This technology can prove useful for public safety since there are WiFi almost
everywhere these days and all entry points in malls or schools can be covered
very easily. There is a chance this can be misused as well.

~~~
vorpalhex
My mom worked at a bank that installed what they called a "man trap".
Essentially there's a large magnetometer between two sets of heavy doors that
locks the doors if it detects someone with a firearm (or any large block of
magnetic material) has tried to enter the bank.

On any given week, they'd catch about a half dozen police officers, a
maintenance person or two who still had their tools on them, and the
occasional delivery person.

After a few weeks they disabled the system entirely.

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neuralRiot
An interesting article about false positives and negatives and their impact in
the reliability of a detection system. (I believe it has been linked in HN
before) It explains why "95% accurate" is BS.

[https://blog.danslimmon.com/2012/11/02/car-alarms-and-
smoke-...](https://blog.danslimmon.com/2012/11/02/car-alarms-and-smoke-alarms-
the-tradeoff-between-sensitivity-and-specificity/)

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fake-name
"Researchers rediscover non-cooperative radar, news at 11"

It's really, really, really hard to do this with cooperative RF sources and
way way more bandwidth. This is horseshit.

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godelski
So we see forcing the use of clear backpacks as an invasion of privacy but
don't see tech that scans a backpack as invasive?

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adamredwoods
I'm curious if I can do this at home, and if so if there are any plans online
besides the paper. I'd love to play around with it.

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blackaspen
This headline immediately make me think of Arthur C. Clarke's "The Trigger".

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bookofjoe
"The Trigger" (2000):
[https://archive.org/details/trigger00clar](https://archive.org/details/trigger00clar)

