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Posted by joebig 10/27/2024

I discovered mysterious hidden signals on a public radio channel (2013) [video](media.ccc.de)
273 points | 67 commentspage 2
ddtaylor 10/27/2024|
I love the CCC website and the fact they host their own videos for a lot of reasons, but for some folks here is the YouTube video link:

https://www.youtube.com/watch?v=CnnbFWTNxZI

Aachen 10/27/2024||
For what folks would that be, then? Genuinely wondering why you'd want to click the big tech instead of self hosted link instead
runj__ 10/27/2024|||
Someone wanting to subscribe to the YT-channel? I don't visit 500+ blogs per day just to check if there's something new. I do miss Google Reader, I think about it almost every single day, I tried using other tools but I really think the RSS-era is over.
musictubes 10/27/2024||
Maybe I’m doing it wrong but RSS works just fine most of the time for me. I use NewsBlur and does everything I need and more. What did reader have that no other RSS service doesn’t?
ddtaylor 10/27/2024||
There was an alternate timeline where RSS went on to prosper. Instead it turned out like OpenID - a standard most aren't really using and it's all just SSO instead.
immibis 10/27/2024|||
If you're on a smartphone, the Youtube app probably works better than whatever browser you're using. On the flip side, it probably has ads.
ddtaylor 10/29/2024||
FWIW me and my family have the ReVanced apps and we never see any ads.

https://revanced.app/

kchr 10/27/2024||
They seem happy to host media for other conferences as well! <3
jfdi 10/27/2024||
We need a tl;dr on this one!
alwa 10/27/2024||
At a very quick skim, seems she detected and decoded the RDS signal in the 57kHz subcarrier of an FM broadcast.

https://www.mediarealm.com.au/articles/fm-rds-radio-data-sys...

anthonyeden 10/27/2024||
That Media Realm site is mine. Thanks for linking! RDS is one of those technologies that’s been around for decades and still amazes people. You can buy hardware encoders for about AU$500 these days, and I love introducing stations to it and getting their name and song data to show up on car radios.
melenaboija 10/27/2024|||
This is the blog post[1] from the presenter explaining part of it, with this request in the messages lol:

- Sad to request, but can you take thisoffline. It is kind of our service you hacked :)

[1]https://www.windytan.com/2013/05/a-determined-hacker-decrypt...

alwa 10/27/2024|||
Thank you for that! I didn’t have the patience for the video, but I found her pen-and-paper decryption in that blog post absolutely lovely.
lelandfe 10/27/2024|||
That “take this post down on the first appearance of any complaint from any party” tact sure changed in a hurry, huh
TechDebtDevin 10/27/2024|||
1.75x, I can't watch any video at any other speed at this point.
squarefoot 10/27/2024||
Ever tried with Louis Rossmanns or Network Chuck videos? I can't watch them at more than 0.75.
pestatije 10/27/2024||
[flagged]
pastage 10/27/2024|||
She was aware but the talk is a walk through how easy hacking is. Not giving up and being interested enough to find out more. Really recommend the talk and her blog.
alfiedotwtf 10/27/2024||
This!

Unless something is theoretical impossible, the only thing stopping a determined hacker is the amount of time and coffee in reserves.

IAmGraydon 10/27/2024||||
You managed to be incorrect twice in one sentence. Well done. Actually watch the video. It's quite interesting.
pestatije 10/27/2024||
enjoy patronising dont you? not well done
DrillShopper 10/27/2024|||
She
amatecha 10/27/2024||
The actual title of the page is "My journey into FM-RDS" which definitely gives a better summary than what the current HN title says.
dang 10/27/2024||
I had switched it to that, but then noticed that joebig had used the subtitle, which is also legit.
lostemptations5 10/27/2024||
I would have never read your title. The whole reason I clicked was because of the mystery element.
jonex 10/27/2024|||
To me it sounded like click bait. So I checked comments and concluded that it was indeed about the very visible RDS signal and not some hidden channel used by some secretive agency that would indeed be somewhat mysterious.

I don't think the fact that it worked in generating clicks is really an argument for bait titles. Given the positive comments about the content I think some editorializing could have been helpful to focus on the hacking journey aspect though, which seems to be the point rather the specifics of RDS itself.

CyberDildonics 10/27/2024||||
Why do you need to be manipulated into reading something? When it turns out they are calling standard radio data "mysterious" don't you feel lied to?
pessimizer 10/27/2024|||
Isn't that the definition of clickbait?
quink 10/27/2024||
(2013)
dang 10/27/2024|
Added above. Thanks!
benjamaan 10/27/2024||
[flagged]
ezcrypt 10/27/2024|
Is the Finnish bus stop timetable data channel well documented, though? Not sure, maybe it is?
xattt 10/27/2024|
I’m curious how folks who have the know-how to dissect a phenomenon “miss the forest for the trees” when they stumble upon a “mysterious” signal.

Alternate data streams in FM like RDS, IBOC audio and FM time are not some new-fangled tech. This would/should be the first place to go to if you saw a signal that’s not modulated to analog audio.

Of course, the whole mystery aspect is just a hook and helps move the story along.

sriram_malhar 10/27/2024||
Oona (the author) knew about the existence of such things; it wasn't a mystery. The only reason it was strange is that because her radio had been knocked about during a move, it was strangely down-shifting the data channel ... she was not monitoring the FM (from what I could make out), but the actual audio from the radio.

This was just ('just' for her, impressive for me) an exercise of going down the rabbit hole, and then curating that tour for us.

ezcrypt 10/27/2024||
Rather, I don't think the data channel was actually down-shifted, but that it wasn't filtered out (probably due to a broken analog filtering circuit after the fall), so it was still outside of the audible spectrum but available to the sound card and hence visible in her software spectrum analyzer. It also sounded like she was seeing some aliasing effect, i.e. that the data signal was probably out of band for the sound card ADC, but "folded" down into the sampler frequency range due to Nyquist folding "magic" (which is maybe what you meant with "down-shifting", now that I think about it?).
sriram_malhar 10/27/2024||
She does speak of aliasing.
therein 10/27/2024|||
Yeah more realistically it was like:

> I was looking at FM radio channels on SDR (rtlsdr came out in 2010) and noticed the RDS. So I looked into it.

dangsux 10/27/2024||
[flagged]
xattt 10/27/2024|||
Look, I’m all for someone being excited for something they’ve never explored before. There is a joy in personal discovery of things you see.

I’m not a fan of a fabricated premise in order to show “look how brilliant I am, I discovered RDS from first principles” when this mostly documented (1).

In contrast, look at the Mike Harrison Eidophor talk. The guy pieced together a history of a significant technology that is otherwise poorly recorded on the Internet (2). This is new and novel info.

(1) https://www.2wcom.com/fileadmin/redaktion/dokumente/Company/...

(2) https://hackaday.com/2016/04/19/mike-harrison-exposes-hot-oi...

ezcrypt 10/27/2024||
I mean, she was pretty clear about why she found the signal, and that she read the RDS documentation in order to decode it, etc.

I think the more fun part was towards the end, when she brute-forced decryption keys for traffic information coordinates and also found the (AFAIK) non-standard Finnish bus stop time table information in another band and reverse-engineered that, and I think that was the takeaway of the talk.

spacecadet 10/27/2024|||
Why does anyone need to? I would imagine billions of personal discoveries go unannounced every day. Is it a good use of resources to add more noise to world when you discover something that is already well documented? I don't think so, but then again everyone seems to have been trained to share personal discoveries like it's a grand discovery, for the sake of self advertising?
sriram_malhar 10/27/2024|||
Did you see the video? There was one proprietary, weakly encrypted part that she discovered, cracked and documented.

Secondly, while individually each thing is independently documented (RDS, Nyquist criteria, sound cards, FSK/QPSK, etc), it is nice to see someone bring all of it together. Surely you don't mean to say that you have not relied on web resources to pull together a project, where one _could_ go to more primary sources, but you are thankful that someone showed you the way?

Like someone said, "Look around you. Everything is someone's passion project". I welcome everyone's passion project. It is not noise if I am interested.

hooverd 10/27/2024||||
Yes. Those discoveries can add context to things that are already "well-documented." I'd hate a world where's no information about topics other than official (tm) documentation. It's sometimes rediscovering things are that implicit knowledge by the people who made the documentation, because how could they consider anyone not knowing something so obvious.
yellow_postit 10/27/2024|||
Sharing and discovery is a fundamentally human act. It’s not noise. Celebrate people that want to learn, share and develop ideas.

Obligatory XKCD “Ten Thousand” https://xkcd.com/1053/

dangsux 10/27/2024||
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