[HN Gopher] The Taylorator - All Your Frequencies Are Belong to Us
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The Taylorator - All Your Frequencies Are Belong to Us
Author : todsacerdoti
Score : 190 points
Date : 2025-01-27 17:42 UTC (5 hours ago)
(HTM) web link (www.scd31.com)
(TXT) w3m dump (www.scd31.com)
| jalk wrote:
| Otherwise known as frequency swifting
| buzzm wrote:
| Very good.
| westonmyers wrote:
| "... frequency swifting" Get out of here. lol
| mrandish wrote:
| Yeah, like how...
|
| PSK = Phase Swift Keying
|
| TDM = Taylor Division Multiplexing
| myself248 wrote:
| With some filtering on the output to knock down harmonics and
| aliasing noise, and as long as the power output is low enough,
| this could actually be legal in the US. IANAL, etc, but this is
| my understanding:
|
| It's actually ridiculously tricky to measure transmitter power
| output in the terms that the FCC regs are written in, but the
| rule of thumb is that, given the receiver sensitivity of a
| typical radio, if you lose the signal when you're more than 200
| feet from the transmitter, you're probably in the clear.
|
| This means a perfectly legal power level would be more than
| adequate to cover your house, office, hackerspace, or whatever.
|
| https://www.fcc.gov/media/radio/low-power-radio-general-info...
| trod1234 wrote:
| The main problem with this line of reasoning is that it
| neglects important parts defined elsewhere making it seem like
| this is legal when its not. IANAL, but I do hang out with a lot
| of hammies. You can't help but absorb a lot of technical stuff
| with them around.
|
| Like for example, https://www.fcc.gov/enforcement/areas/jammers
|
| It need not saturate the bands, you technically are in
| violation the moment a non-licensed entity has caused
| interference to a licensed entity.
|
| Willful is a pretty low bar since general intent can be derived
| from any related negligent acts. Its pretty safe to say
| transmitting on these bands without a license is illegal, and
| yes its a fairly big deal.
|
| Most of the public radio spectrum has been monitored, and
| archived for later retrieval if circumstances dictate since the
| 60s. There are services that aggregate this data and make
| realtime info available globally from satellite systems.
| Trilateration of signals is fairly trivial in most cases.
|
| You may not get caught if you always stay below the noise
| floor, but you can't really have any real use of the spectrum
| in doing so, and algorithmic scanning of structured signals is
| always improving.
|
| It is really negligent to make it seem like these things are
| legal, when they aren't, and the author should get in trouble
| for that.
|
| A simple disclaimer isn't going to cut it when then primary
| purpose is effectively breaking the law in many civilized
| nations.
| vel0city wrote:
| Eh, if they're so low power that they're not stepping on
| their neighbor's reception I'd personally say it's fine. Tree
| falling in the woods situation and all. That definitely
| varies based on where one is playing around with such things,
| and it's always important to understand how far your
| transmissions are actually going (which can be surprising if
| you don't have much experience with it!).
|
| Someone in a shed on a few acres playing around with an SDR?
| Go ahead, I don't care. Playing around in an amateur anechoic
| chamber, have fun if you're sure you're containing things. On
| a desk in a random apartment in Manhattan? What an asshole,
| call the FCC.
|
| Is it potentially against the law to do this? Yeah, probably.
| How bad is it? Somewhere around jaywalking on an absolutely
| empty street and dumping waste in a park, greatly depending
| on multiple factors.
| lenerdenator wrote:
| For what it's worth (which isn't much), all of that hinges
| upon the FCC's motivation and capacity to enforce its rules.
|
| If amateur and citizens band radio shenanigans over the last
| few decades have proved anything, it's that you have to be an
| _absolutely massive pain in the radio-wave-receiving public
| 's ass_ to really get their attention.
|
| If you had this device on 14.300, 7.200, or channel 6? Meh.
| No one's gonna care.
| jandrese wrote:
| In my town there was a guy who was absolutely obliterating
| 88.5 as well as 88.3 and 88.9 broadcasting some Hispanic
| hip-hop with some grossly overpowered local transmitter. He
| overpowered the stations on the entire east side of town.
| It took over 6 months before it was shut down. I think the
| FCC penalties are so harsh because their enforcement arm is
| so small that they can only go after the most blatant
| offenders. Not that I would want to risk fate given how
| harsh those penalties are.
| alibarber wrote:
| I hold a ham radio licence in a couple of countries, although
| what's happening here is far outside of the remit of ham
| operations.
|
| I'm pretty certain this is not legal in my locale, but I
| don't think the author of the article is making this out to
| be legal - and I don't think they should get in trouble for
| any of this publishing [assuming you're adressing them, not
| the commenter]. Perhaps the equivalent of a script kiddy
| could get up to no good with it, nothing new from the last 20
| years of computer hacking then.
|
| I'd far rather see enforcement and ire directed at the
| proliferation of poorly shielded junk that spews noise all
| over the spectrum, at surprisingly high power, that seems to
| have no trouble being sold online or imported for sale in
| many countries - and is often, strictly speaking, not legal
| with regards to necessary EMC, and probably safety,
| standards.
| myself248 wrote:
| How do you interpret Bulletin 63?
|
| https://transition.fcc.gov/oet/info/documents/bulletins/oet6.
| ..
| RobotToaster wrote:
| > if you lose the signal when you're more than 200 feet from
| the transmitter, you're probably in the clear.
|
| With the FCC maybe, but someone far worse will be interested,
| the RIAA. It's copyright infringement by illegal broadcast.
| vel0city wrote:
| If it's intended for personal consumption it's fine. It's not
| copyright infringement to hear my neighbor's stereo if it's a
| bit loud. It is if he's using it commercially for hosting a
| block party selling tickets it's a problem.
| zamalek wrote:
| > It's copyright infringement by illegal broadcast.
|
| And I'd bet they would make a good attempt at fining you for
| each channel that you modulated for.
| gwbas1c wrote:
| And a wonderful April Fool's prank, too!
| buescher wrote:
| If by "ridiculously tricky" you mean "requires specialized
| equipment and domain knowledge". Like say, skiing.
|
| With a cheapish Rigol spectrum analyzer and homebrew receive
| antennas and DIY wooden/pvc tripods you could probably do 3m
| open-air measurements to within 3dB of what you would measure
| in an anechoic chamber at a test laboratory if you were very
| careful. I can 100% assure you that is possible with a
| commercial dipole kit and horn antenna, neither of which is
| that expensive if you're getting paid. This in in the FM band
| so you could use dipoles and a low-end analyzer to the tenth
| harmonic.
| myself248 wrote:
| You can absolutely hook an antenna to a spec-an, but how do
| you calibrate the result? I can get a power measurement of mV
| or dBm at the instrument input, but that's not how the regs
| are written.
|
| They're written as field strength in free space (microvolts
| per meter), which as I understand it, either requires a
| calibrated field probe, or a calibrated antenna. I'm sure
| there's a way to perform such calibrations from first
| principles, but that's where I'm invoking "tricky". If you've
| got a trick to it, please share.
|
| In practice, Part 15.23 is pretty generous about home-built
| equipment, and I think since the "200 foot" thing came from
| the FCC's own mouth, if you can show that you walked the
| perimeter with a portable radio and confirmed that you're
| good, that probably shows good faith on the power issue.
|
| ...
|
| Absolutely yes a spectrum analyzer is helpful to make sure
| your harmonic filtering is working. I would put that forth as
| "good engineering practice" under 15.5, and it's far more
| than any hobbyist could be reasonably expected to do even
| just a few years ago; this equipment has gotten
| mindbogglingly affordable and accessible.
| thijson wrote:
| I remember going to the drive-in movie theater in the 80's. You
| had to tune your car radio to a specific frequency to hear the
| movie audio. If this device had existed back then, you wouldn't
| have needed to tune your car radio at all. I doubt the neighbors
| would have liked that though. As an aside, I remember being
| jealous of the neighbors because they got to watch all these
| movies for essentially free. The irony is that today, we're
| bombarded by content, it's become essentially free.
| imoverclocked wrote:
| > you wouldn't have needed to tune your car radio at all
|
| You still need to tune it but there are many "center
| frequencies" that can be tuned instead of just one. So, you
| wouldn't have to tune _far_ but you would still have to tune :)
| If you had a knob like most radios in the 80 's it would save
| you from cranking the knob several times to get the dial into
| the right range before fine-tuning.
| jedberg wrote:
| I think the theory is that every car that has an FM radio has
| it tuned to _something_. So no matter what, as soon as you
| put on the FM radio, it would have the audio.
| imoverclocked wrote:
| Yeah, until you have a 5 year old (probably me in this case
| in the 80s) that plays with random knobs on the dash when
| they get in the car. Is it volume? Is it the tuner? We'll
| know once the car turns on!
| monktastic1 wrote:
| It's broadcasting on _every_ valid ( "odd") frequency. I
| guess it still depends on if you have an analog or
| digital dial.
| dylan604 wrote:
| > You had to tune your car radio to a specific frequency to
| hear the movie audio.
|
| This was great because it allowed for stereo. This also
| replaced the earlier idea of taking the speaker from the pole
| next to the driver's window, and then hanging from the window
| inside the car. This was just a mono speaker, but it was also
| right next to the driver's head. It reduced the drive-in's
| repair bills from people driving away before placing the
| speaker to its host stand (and other hooliganism)
|
| *just to add some color
| abeppu wrote:
| It's kinda refreshing that the "Legality" section is entirely
| concerned with power and frequencies, and not at all about the IP
| rights around Swift's music.
| larrymcp wrote:
| Ah, yeah. If this signal reaches your neighbor across the
| street, then maybe it's a "public performance" and you've got
| to get ASCAP and BMI licenses.
|
| (And start taking requests.)
| Waterluvian wrote:
| I'm going to need a device that allows requests to be made by
| calling _any_ phone number.
| dylan604 wrote:
| Good luck getting anyone to answer the phone to take the
| request. I'd suggest not naming your station "Spam Risk"
| tobyjsullivan wrote:
| This might help
|
| https://en.wikipedia.org/wiki/Stingray_phone_tracker
| badgersnake wrote:
| Who cares? She basically splits Spotify's revenue with Joe
| Rogan, she does okay.
| formerly_proven wrote:
| > I'm not convinced that I'm operating anywhere close to peak
| efficiency. There may be some huge DSP-specific shortcut that I'm
| overlooking - I'm certainly no expert. But the current code works
| well enough.
|
| Something along the lines of taking the FM at baseband, transform
| to frequency domain, copy result n times and shift the
| coefficients to the right indices, much wider ifft to RF should
| work, right?
| gorkish wrote:
| Regarding wideband signals muxing/demuxing
|
| Yes, modulate then FFT for each signal, do the upconversion and
| mixing in frequency domain, then a single large IFFT to give
| the final bitstream. Roughly the inverse of this (single large
| FFT, filter in frequency domain, and IFFT individual signals)
| is how the 'wideband sdr' at utwente.nl works to support
| hundreds of simultaneous receivers on a single gpu.
|
| The amateur radio folks working with these techniques on HPSDR
| hardware were calling the technique "Direct Fourier Conversion"
| but I do not know if they ever got to a releasable state. They
| spent an awful lot of time prematurely optimizing their stuff
| to run on the original Jetson board which was not really
| adequate to the task, so I think that was likely frustrating
| and killed momentum.
| threeio wrote:
| Ham radio has gotten me into more devious activities than I'd
| like to admit... but that's half the fun of experimentation :)
|
| Well done :)
| mrandish wrote:
| From phone phreaking 40 years ago to FPV RC, I've found it to
| be a good indicator you're focusing on interesting emerging
| technologies when fellow early adopters in your new hobby say
| "Technically, this isn't even illegal... yet."
| mikewarot wrote:
| I was hoping this was a Tayloe Mixer[1] based SDR. The Tayloe
| mixer has excellent image and harmonic rejection.
|
| <Oops... I missed the important detail about 100 different
| songs... sorry. I'd suggest putting the hit "Never gonna give you
| up" on loop for that version of the project>
|
| In hardware, it would be easier to feed a 200 khz square wave
| into a diode and pull off the first 10 mhz of harmonics, low pass
| filter it, and mix that with 99.1 Mhz fm audio to get 88.1 to
| 108.1 Mhz fm at 200 khz spacing.
|
| In software, you should be able to precompute a complete one
| cycle composite of -10 to +10 Mhz sine waves spaced 200 Khz
| apart. You could then loop this abitrary waveform and multiply it
| by an FM modulated source at 99.1 Mhz to get the same effect with
| a lot less processing power. This is the kind of thing GNU
| radio[2] is perfect for.
|
| <Correcting the above>
|
| Precompute the FM signal for each of the songs in it's channel
| from -10 to +10 mhz for the length of the song. Store them as 16
| bit IQ samples. Each file will be different length.
|
| Loop though all of the songs, adding all of the components into a
| 32 bit I and Q sum. Round those to 16 bit values, or as
| appropriate for your SDR transmitter. You should have a very easy
| to compute 100 channel FM station with each channel separately
| timed.
|
| [1] https://www.norcalqrp.org/files/Tayloe_mixer_x3a.pdf
|
| [2] https://www.gnuradio.org/
| xg15 wrote:
| > _The Taylorator is a piece of software which allows me to flood
| the FM broadcast band with Taylor Swift 's music._
|
| I suppose, you could call it a _Taylor Series_.
|
| (I'm sorry)
| huel000101 wrote:
| Great insight into frequency modulation! Thanks for sharing.
| Terr_ wrote:
| From the title I expected it to somehow be related to Taylor
| polynomials being used to approximate sinusoidal radio stuff.
|
| https://en.wikipedia.org/wiki/Taylor_series
| malwrar wrote:
| I might have missed it, how does OP broadcast across 80mhz with a
| 20mhz SDR? I think my mental model about SDR capability is wrong,
| does sample rate not necessarily gate the range at which an SDR
| can TX/RX?
|
| Really funny idea!
| Centrino wrote:
| The FM band, from 88 to 108 MHz, is 20 MHz wide.
| adzm wrote:
| > an SDR is that a sound card takes real-valued samples, and an
| SDR takes complex-valued samples
|
| Coming from a DAW background this concept was incredibly
| interesting. I am curious if stereo audio has ever been
| represented in this way, or if it is generally just used for the
| half sample rate?
|
| Actually thinking on this now I guess that doesn't really make
| sense. But still really interested in this alternate view of
| sampling waveforms.
| wrs wrote:
| Testing has shown that humans can't hear phase differences,
| unlike radio demodulators, so there's no real use for giving a
| sound card complex numbers.
|
| (Before someone replies about snare drums, 3:1 rule, etc. -- of
| course if there are phase differences in the audio _before you
| mix it_ , it will cause audible artifacts in the mixing
| process. Which is why there's an effect called a "phaser".)
| fryd_w wrote:
| any notable historical events or uses involving this?
| dylan604 wrote:
| Re: "I wrote a rational resampler which does this by upsampling,
| linear interpolating, and decimating to the target sample rate."
|
| Where would you source Swifty music that wasn't already at
| 44.1kHz or 48kHz sample rates? Curiously, what sample rates were
| these at, and why?
| tamimio wrote:
| > The Taylorator is a piece of software which allows me to flood
| the FM broadcast band with Taylor Swift's music.
|
| You don't need an SDR, just put on her song and most people at
| traffic lights will roll their windows up!
|
| That being said, from my experience, power will be the deciding
| factor. I tried both LimeSDR and BladeRF, and when maxing out the
| power, they overheat really fast, so they probably will only work
| while driving/cycling so no obstacles. And then again, most
| people use Spotify or similar in their cars.
|
| If it works on AM, however, that would be great to test.
| jefftk wrote:
| Instead of struggling to generate this in real time, perhaps you
| could generate it in advance and loop it? The median Taylor Swift
| song is 3:52, then at 20M samples per second (and four bytes per
| sample) you need a little over 19GB [1] and I think streaming
| from SSD should be fast enough. Could probably also compress it.
|
| [1] 20e6*(60*3+52)*4 / 1e9
| eieio wrote:
| I'm not sure if Stephen is on HN, but I asked him this question
| last week[1]. His response was that since the songs are
| different lengths, a file that was truly loop-able would be
| super long (if you have a 90 second song and a 2 minute song,
| you need 6 minutes of audio to create a file that perfectly
| loops both of them)
|
| Seems like there is probably some set of clever hacks here that
| could get you around this (although I don't know enough about
| radio to propose any); I think I asked about pre-computing some
| state for each song on its own and he had a good response to
| why that either didn't work or didn't help much, but
| unfortunately I don't remember it!
|
| [1] we are both currently at the Recurse Center /
| https://recurse.com
| jefftk wrote:
| I was thinking you could pick a group of songs that were
| close to the same length, and then make up the difference
| with fading, gaps, or a fake DJ? For this to work I think you
| want your overall loop to be just a few minutes.
| moomin wrote:
| And you Taylorate it...
| tetha wrote:
| This is something that would fit right into some dystopian,
| proto-cyberpunk movie.
|
| Like, a bunch of activists need to disable comms of some
| nightshift guards in an area. So... someone figures out how to
| put more juice into this thing to pump out music on all
| frequencies they could have.
|
| Bonus points because this wouldn't just jam their communications
| with white noise. It would be confusing as hell. Taylor Swift on
| the main channel. Switch to the backup. Irish Folk. Switch to
| something you and Bob used some time back. Power Metal! What?
| mrandish wrote:
| I wonder if Rick Astley will be dismayed or delighted to learn
| his music has been displaced by Taylor Swift's as default prank
| audio.
| aaroninsf wrote:
| I am so sad this was not implement in Swift.
| p0w3n3d wrote:
| Must save it. Some day it might be needed to do some advertising
| regarding mutiny against government or to gather people in the
| post apocalypse time...
| anfractuosity wrote:
| I got my laptop to play Taylor Swift on the AM band -
| https://www.youtube.com/watch?v=KH9yb1qFKDY by twiddling the
| memory bus (sounds a bit iffy ;)
|
| Code: https://github.com/anfractuosity/musicplayer
|
| Based on the work of https://github.com/fulldecent/system-bus-
| radio
| dtgriscom wrote:
| > Stations will only appear on odd-numbered frequencies, like
| 88.1 MHz, 94.5 MHz, 107.3 MHz, etc. There's a technical reason
| for this - every FM broadcast takes up about 150 KHz of
| bandwidth, and spacing the broadcasts like this allows for an
| extra 50 KHz of wiggle room.
|
| I believe the odd-numbered frequencies were chosen because if
| only even were allowed then there would be legal knock-down-drag-
| out fights over the round numbers.
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(page generated 2025-01-27 23:00 UTC)