This was a such a refreshing talk. She was monitoring the FM channel using a spectrum analyser (as one does, of course, haha) and got curious about this strange signal showing up next to the FM radio Channel.
The talk is about her attempts to learn about the Radio RDS (Radio Data System) standard, using a sound card to decode signals, finding a bit of bus-related information in that stream is weakly encrypted and proceeding to chasing it down. Very entertaining.
I'm so glad such people exist. I wish I could be one of these fearless and supremely knowledgeable people!
> I wish I could be one of these fearless and supremely knowledgeable people!
There's no trick to it (or there's a massive trick to it), you just refuse to let a mystery go until you know what's happening, mostly because figuring things out is fun.
In the process, you gain a large amount of knowledge.
It comes down to genuine, natural unforced interest (its there or not) and mastering the ability to systematically deal with and how to tackle the next unknown. After years this make you a true wizard.
I also think that figuring things out is one of life's most rewarding experiences.
But I've found out a lot of people don't think like that. I've often been asked "but why are you doing this" on the topic of my "eccentric" projects. People often can't understand why I find it fascinating because they would only find it tormenting.
I found on her website [1] that she released a RDS decoder tool [2] relatively recently (compared to the 2013 of the video at least). Looks like it works with a USB RTL-SDR [3] receiver or a pre-recorded file in a number of formats.
Are there still apps and the underlying hardware in smartphones to receive and decode FM RDS? IIRC some phone chips had FM radio receivers, but there were limitations like needing a wired headphone plugged in so that the headphone cable could be used as an antenna. I know a USB SDR could do it, but it would be neat if this were still a latent capability in the phone.
Of course I did a search in the Play Store but it's crowded with streaming radio apps and SDR apps.
edit: oops you mean specifically RDS. Of that I'm not sure. I just opened the "Radio" app on my phone (for the first time ever!) and you did have to have the headphones plugged in to receive, but I couldn't see anywhere in the really basic looking app for RDS info to show up.
I think nobody has to prevent abuse because listeners will either turn off traffic alerts or switch to a different channel.
Besides that, FM broadcasting isn't a lawless place and is regulated by the government. Abuse will most likely lead to some kind of penalty, but I can't be bothered to read through the laws to confirm it :P
It is a rule in Germany, I know about it because we did some distributed cooperation stuff with community radio stations and some hacking events during the pandemic, and making sure that no matter what happens with the network between the speakers, the coordinating host, and server of the radio station, we never send out silence, was quite an important concern. I can't quote you the exact line of the law,though.
Not sure about TA, but definitely saw radio station in Indianapolis using RDS to broadcast advertisements. In between the artist/song info, ads for an injury lawyer appeared. Thought it was super lame use of RDS.
In this case I think it's mostly about using different sub-carriers (kind of a "channel in the channel"), so that the data information and the audio are separated in frequency and do not disturb each other. That's generally called Frequency Division Multiple Access (FDMA), IIRC.
Another more advanced technique is Code Division Multiple Access (CDMA), e.g. used by GPS and some mobile communication modulation schemes. It allows you to have multiple senders on a single radio carrier frequency, and the receiver "selects" which sender to listen to by knowing its "code".
There's also Time Division Multiple Access (TDMA), i.e. senders take turns sending content in allocated time slots.
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.
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?
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.
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.
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.
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.
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.
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.
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?).
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.
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.
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?
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.
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.
The talk is about her attempts to learn about the Radio RDS (Radio Data System) standard, using a sound card to decode signals, finding a bit of bus-related information in that stream is weakly encrypted and proceeding to chasing it down. Very entertaining.
I'm so glad such people exist. I wish I could be one of these fearless and supremely knowledgeable people!