18 comments

  • sriram_malhar4 天前
    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!

    • stavros4 天前
      > 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.

      • smetj4 天前
        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.
      • deskr4 天前
        > mostly because figuring things out is fun

        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.

      • amelius4 天前
        What if the data is encrypted? Do you keep on trying in a brute-force way?
        • stavros4 天前
          You do whatever you think is fun, what do you mean?
  • matthberg4 天前
    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.

    [1]: https://www.windytan.com

    [2]: https://github.com/windytan/redsea

    [3]: https://www.rtl-sdr.com/about-rtl-sdr

    • mbirth3 天前
      I’ve used this to experiment with TMC messages and trying to unscramble TMCPro. Fun times!
  • Zigurd4 天前
    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.

    • brokenmachine3 天前
      Yes. My Samsung has an FM radio. A lot do.

      https://www.gsmarena.com/results.php3?chkFMradio=selected returns 7010 models, lol.

      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.

  • 08984 天前
    One thing I often wonder about with RDS: How do they stop the traffic alert (“TA”) feature being abused by stations to grab listeners?
    • looperhacks4 天前
      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

    • fhars4 天前
      The same way the prevent stations from broadcasting 90 seconds or more of pure silence: you loose your license if you do.
      • GranPC4 天前
        > broadcasting 90 seconds or more of pure silence

        Have a link or info on this? Sounds interesting but can't find anything.

        • fhars3 天前
          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.
    • ARob1094 天前
      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.
    • GJim4 天前
      They don't.

      Back in the day, it wasn't uncommon for pirate radio stations to drum up listeners by using TA to advertise short snippets.

    • teeray4 天前
      The almighty FCC fine is the deterrent
  • alfiedotwtf4 天前
    "So I got to work"...

    I love that hacker mindset :)

  • Aachen4 天前
    Wow, was that 2013? I saw this talk irl, can't believe it has been that long
  • mbirth3 天前
    Not sure whether it’s part of her talk, but this demonstration of the RDS stream she uploaded on Soundcloud is pretty cool:

    https://soundcloud.com/windytan-1/rds-mixdown

  • user39393824 天前
    I was picking up WCBS in NYC at 5.105 GHz, near the antenna at Empire State. Never could figure it out, their engineers didn’t know why either.
    • wildzzz4 天前
      It was probably getting picked up by some component in a microwave transmitter and getting mixed into the signal.
  • stavros4 天前
    This was great, I love these rabbit holes people go down, and it's great when they then share the results. Very fun watch.
  • yarg4 天前
    This makes me wonder, how do you reliably and securely encode steganographic content for distribution within a noisy medium?
    • ezcrypt4 天前
      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.

  • ddtaylor4 天前
    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

    • Aachen4 天前
      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__4 天前
        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.
        • musictubes4 天前
          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?
          • ddtaylor3 天前
            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.
      • immibis4 天前
        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.
    • kchr4 天前
      They seem happy to host media for other conferences as well! <3
  • 4 天前
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  • jfdi4 天前
    We need a tl;dr on this one!
    • alwa4 天前
      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...

      • anthonyeden4 天前
        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.
    • melenaboija4 天前
      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...

      • alwa4 天前
        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.
      • lelandfe4 天前
        That “take this post down on the first appearance of any complaint from any party” tact sure changed in a hurry, huh
    • TechDebtDevin4 天前
      1.75x, I can't watch any video at any other speed at this point.
      • squarefoot4 天前
        Ever tried with Louis Rossmanns or Network Chuck videos? I can't watch them at more than 0.75.
    • pestatije4 天前
      [flagged]
      • pastage4 天前
        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.
        • alfiedotwtf4 天前
          This!

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

      • IAmGraydon4 天前
        You managed to be incorrect twice in one sentence. Well done. Actually watch the video. It's quite interesting.
        • pestatije4 天前
          enjoy patronising dont you? not well done
      • DrillShopper4 天前
        She
  • amatecha4 天前
    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.
    • dang4 天前
      I had switched it to that, but then noticed that joebig had used the subtitle, which is also legit.
    • lostemptations54 天前
      I would have never read your title. The whole reason I clicked was because of the mystery element.
      • jonex4 天前
        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.

      • CyberDildonics4 天前
        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?
      • pessimizer4 天前
        Isn't that the definition of clickbait?
  • quink4 天前
    (2013)
    • dang4 天前
      Added above. Thanks!
  • 4 天前
    undefined
  • benjamaan4 天前
    [flagged]
    • ezcrypt4 天前
      Is the Finnish bus stop timetable data channel well documented, though? Not sure, maybe it is?
  • xattt4 天前
    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_malhar4 天前
      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.

      • ezcrypt4 天前
        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?).
    • therein4 天前
      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.

    • dangsux4 天前
      [flagged]
      • xattt4 天前
        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...

        • ezcrypt4 天前
          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.

      • spacecadet4 天前
        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_malhar4 天前
          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.

        • hooverd4 天前
          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_postit4 天前
          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/