Slashdot Mirror
Finnish Hacker Isolates Helicopter GPS Coordinates From YouTube Video Sounds
An anonymous reader sends a post by Finnish electronics hacker Oona Räisänen, who heard a mysterious digital signal in the audio accompanying a YouTube video of a police chase. The chase was being filmed by a helicopter. Räisänen wrote: "The signal sits alone on the left audio channel, so I can completely isolate it. Judging from the spectrogram, the modulation scheme seems to be BFSK, switching the carrier between 1200 and 2200 Hz. I demodulated it by filtering it with a lowpass and highpass sinc in SoX and comparing outputs. Now I had a bitstream at 1200 bps. ... The bitstream consists of packets of 47 bytes each, synchronized by start and stop bits and separated by repetitions of the byte 0x80. Most bits stay constant during the video, but three distinct groups of bytes contain varying data." She guessed that the data was location telemetry from the helicopter, so she analyzed it to extract coordinates. When she plotted them and compared the resulting curve to the route taken by the fleeing car in the video, it was a match.
i think i'm in love with this women.
never bring a twinkie to a food fight.
I'll be in the kitchen, making this woman a sandwich.
She washe one driving the car being chased by the police.
#DeleteChrome
There was a time, before we all lost our minds to Pong, Asteroids and Zelda (yes, I go way back) where we also spent time taking our world apart and figuring out how to make it better.
Oona rocks! She should be rewarded somehow.
BTW - the end of the article finally explains how a megahertz signal found its way onto the audio track.
Pfft, it's fucking magic to me dude, but I'm a software guy. I think the so what is 2 things - first it shows crazy shit you can do that people don't expect with Youtube or other short clips, and second it's a chick who did it.
Oona had better be glad she's Finnish. If she did that in the US, she could expect jack-booted thugs from Homeland Security bashing her door down. That data is SEKRET! The fact that it's only perceived as secret by said ignorant thugs because the marketing department of the vendor told them so is completely lost in the general panic. TUR'RISTS could FOLLOW the HELICOPTER! Beat to quarters and man guns!
I'd like to think I was exaggerating for effect, but judging by the past decade, I'm really not. The current security apparatus really is self-parodying.
(For those who want to bitch about how this perception runs contrary to Slashdot groupthink about the threat posed by that apparatus, I say only this: some of us are capable of projecting into the future. We want the spying and the blundering belligerence stopped because it might not always be blundering or incompetent. It still manages to be mortally dangerous even now. It could get much much worse.)
You become this skilled, by turning it into an obsessive hobby.
Although I think that people doing interesting stuff getting double the attention because they're female, is a weird kind of inverted sexism.
It would be a travesty if women were put off innovating like this and following their technical passions, because of arguably-sexist backhanded putdowns, or neckbeards slobbering all over them merely because they're female.
A story worthy of slashdot. Please post more of these (not being sarcastic).
Only the State obtains its revenue by coercion. - Murray Rothbard
So what? It was still fun, as in "this Youtube video contains more data than meets the eyes. Let's find out what it is."
As a ham radio enthusiast, I get the same pleasure decoding the bits of morse code that can be heard in movies from time to time: usually it's pretend morse code, but once in a while you hear a bit of a real transmission that's been overlaid onto the soundtrack by the sound engineer who didn't have a clue that what he used actually meant something totally unrelated to the movie.
In fact, I heard a CQ call followed by a callsign in a scifi B-movie from the 90s once, and sent a QSL card to the owner of the callsign in question. He answered me saying I was one of only 5 people to have done so over the years. How fun is that?
So yes, the code is known, there's nothing special about it, but she had fun digging out unexpected information, and I had fun reading about it. Stop being so jaded.
"A door is what a dog is perpetually on the wrong side of" - Ogden Nash
A story worthy of slashdot. Please post more of these (not being sarcastic).
I second this.
I'm adequately supplied with political stories, you can get those anywhere. Stories that raise the indignation level are also common - "oh! how unjust that is!".
When you have stuff that nerds find interesting that you don't see everywhere else, nerds will come here to see it.
thanks for calling it morse code.
when I see people refer to it as 'morris code', I feel the need to remind them that that's a secret language, known only by cats.
--
"It is now safe to switch off your computer."
Someone on this article truly deserves the title of a "hacker"
0x80 is just a null byte with odd parity. What she apparently missed is that this is bog-standard Bell 202 AFSK (1200 baud) with 7 data bits and odd parity, and the data is ASCII. By throwing away the top nybble, she was throwing away the parity bit and the top 3 bits of the ASCII encoding of decimal digits. The fact that it was a parity bit should've been pretty obvious, since the top nybble flips between 0x3x and 0xbx in the pattern that you'd expect for a parity bit.
You can decode it with off the shelf software, throw away the top bit, and get back mostly ASCII:
./minimodem --rx 1200 -f ~/helicopter.wav | tr '\200-\377\r' '\000-\177\n'
$
### CARRIER 1200 @ 1200.0 Hz ###
282 0002.3
#L N390374 W09432938YJ
#AL #NA 282 0002.3
#L N390374 W09432938YJ
#AL #NA 283 0002.3
#L N390372 W09432928YJ
#AL #NA 283 0002.3
#L N390370 W09432918YJ
#AL #NA 283 0002.3
#L N390370 W09432918YJ
#AL #NA 283 0002.3
[...]
I'm actually surprised that she missed / didn't mention this, considering her experience with signals analysis and demodulation. This is pretty much as basic as telemetry data modulation gets! Then again, as a reverse engineer myself, sometimes we get caught up doing deep analysis of something that later turns out to be totally trivial :)
... and not as the negative it is most often used nowadays ...
Did you look at her profile? She's interested in codes and ciphers and vintage electronics so this sort of is her hobby. Many here seem to bash her because this isn't something spectacular but she never claimed it was. All she did was to write about her observation in her own blog.
How come I only see technical women smarter than me on the Internet?
Selection bias. By means of comparison, only beautiful girls get caught in the storm of events in modern action movies, ugly slobs are always safe. (Well, I'm being somewhat facetious here, but you catch my drift.)
Ezekiel 23:20
I know I still enjoy a good Hollywood starlet spread spectrum today.
I am Bennett Haselton! I am Bennett Haselton!
In chemistry and physics courses you'll find you often do lab work not in discovery of new things but to prove things that are already known. It turns out to be pretty simple to do an experiment to prove that two related theories can be measurably shown to be not false, through some apparatus under some paradigm.
So this woman used existing knowledge of how GPS works, of audio modulated data, and a chase that she also apparently knew the location of, and showed that the location of the chase matches the location being communicated. Okay, so that's cool.
But what did she accomplish? I am, of course, asking this from the "how is this news" rostrum. It's a great proof of theory but what the hell does it have to do with anything?
Oh, wait. The elephant in the room. I see what's going on, here, you geeks got all fucked up in the head again because here comes another woman with skills.
A man who turns into putty for women isn't trustworthy, you know that? Strong women prey on those guys and they become security concerns.
If you can't treat women as equals, then all of your wowie-zowie about women "doing guy things" is empty. You're more self-impressed at other males than impressed at this woman's potential.
"Stratigraphically the origin of agriculture and thermonuclear destruction will appear essentially simultaneous" -- Lee
A weird kind of inverted sexism? There's only one kind of sexism. The fact that the media hypes any sort of female accomplishment in male dominated activities, often while not even mentioning the name of men who do interesting things by name, is blatantly sexist. Of course, even pointing this out is considered 'misogyny' somehow. Right, right.. Yes, those poor helpless women shouldn't have to tolerate any behavior they don't want, when they don't want. How could their lives ever be complete without white knight manginas like you rushing to their defense?
The only reason this is an article here is because of gender politics. If this accomplishment was done by a man, it wouldn't warrant special attention and would not be posted here. Reading data from a radio broadcast is nothing new and is routinely done by the ham radio crowd.
It's sad that this got an insightful mod. The fact that everyone jumps to potential mate every time a woman does something is one of the biggest barriers to women in technical fields.
First off, if you think "mate" is what love is about, you're the one with the problem.
Second, one person is not "everyone."
Third: did you really think the poster was serious? It was a hyperbolic statement, meant as a strong statement of respect.
Fourth: we can't desire a woman's lifelong companionship for her body (sexual objectification), but please do explain what is wrong with desiring a woman's companionship for her impressive work? Because you do realize that damn near every straight woman on this planet selects her mate by his accomplishments, wealth, and social standing, right?
Please help metamoderate.