[Stephen] recently wrote in to share his experiments with using the LimeSDR mini to conduct a bit of piracy on the airwaves, and though we can’t immediately think of a legitimate application for spamming the full FM broadcast band simultaneously, we can’t help but be fascinated by the technique. Called the Taylorator, as it was originally intended to carpet bomb the dial with the collected works of Taylor Swift on every channel, the code makes for some interesting reading if you’re interested in the transmission-side of software defined radio (SDR).
The write-up talks about the logistics of FM modulation, and how quickly the computational demands stack up when you’re trying to push out 100 different audio streams at once. It takes a desktop-class CPU to pull it off in real-time, and eats up nearly 4 GB of RAM.
You could use this project to play a different episode of the Hackaday Podcast on every FM channel at once, but we wouldn’t recommend it. As [Stephen] touches on at the end of the post, this is almost certainly illegal no matter where you happen to live. That said, if you keep the power low enough so as not to broadcast anything beyond your home lab, it’s unlikely anyone will ever find out.
…and enter the Haminators to nerdsplain the moral and legal ramifications of why this should not be talked about….in 3…2…1
This project has the side effect of making every HAM increase the noise floor on all frequencies between 20 and 20000 Hz.
The bar is high enough on this one it isn’t a serious threat to anyone.
Is the math any easier if it’s the same audio program? Like an endless loop of an old ClearChannel commercial on every station in an area?
There are shortcuts in case the content of each channel is the same (multiply the baseband modulated signal with a comb signal). An FFT filterbank could make the different content case more computationally friendly.
That’s a wonderful way to jack up the noise floor on every harmonic frequency from DC to daylight. Cool thought experiment, but please, for the love of all that’s good in the world of radio, please never actually do this.
Next, could we please have some tutorials on how to reduce the z-axis anomalies in home-based 3-D printing of firearms? Asking for a friend, just for the pure tutorial aspect of 3-D printing because I’m sure we’d all find that educational.
Seems like a reasonable request, given there’s plenty of locations where it’s legal.
For that you’ll want Bang-a-Day.
That is not the site that you think it is.
Just like rebelious MILF in Philippines.
But why bother with those CNC plastic squirters? Over time I’ve equipped my little house basement workshop with a chinese 360×1000 lathe, mini mill, Lincoln MIG/TIG/MMA inverter welder and some other metalworking tools.
Last year I manufactured my 4th STEN-like machine gun and recently I started working on a more ambitious project do make a DIY VSS Vintorez replica using subsonic 9 mm rounds. Thank heavens for World of Guns game, it’s pretty easy to replicate the design in CATIA but the hard part will be to (re-)design for manufacturing with what tools I have.
If you think obtaining ammunition without a firearms permit is hard, well… yes. But nail gun cartridges are easily available and being very careful it’s possible to extract gunpowder and primer to manufacture your own centerfire casings. The easiest part is casting lead bullets because ingots readily available at places like Olx.
I struggled with making rifled barrels but on my 4th STEN I finally got the process perfected. It’s amazingly accurate for an open-bolt design.
“It takes a desktop-class CPU to pull it off in real-time”
What am I missing? Desktop class CPU isn’t exactly hen’s teeth. Is it meant to convey that it is processor intensive?
Thx fun article.
First, not sure why my other comment was a reply to yours.
Second, hard to tell if you are serious or not but if so that is awesome and good job I’m serious.
for everyone else- manufacturing firearms in US requires no federal permits or anything else. Certain jurisdictions have additional regulations however. Also about zero people are aware that fully automatic firearms are very legal (as are suppressors) federally they only require a $200 tax stamp and do require registration. There are exceptions (1986 ruling etc) and it’s legally a bit more complex than I am making it but that’s the gist.
If you think about it it has to be the case otherwise the rules governing any gunsmith would be impossible because the definition of manufacturing vs repair would be so complex as to be useless.
In the U.S. manufacturing – and let me be specific and clear here – fully automatic firearms requires a Class III license and it’s tricky because there’s a liminal period where you’ve manufactured it but not registered it. I once had plans for building a semiauto ghost gun but then my state made it illegal so I didn’t. If I need a gun I can just go down to Talley’s Corner and get one.
There’s an interesting twist in U.S. law at the federal level: you can sell your neighbor a mill but you cannot sell them a mill for manufacturing a ghost gun. Coming and going is how they get you. For a long time the BATFEM&MCIAGTBQ said that a shoestring was a machine gun then saner heads prevailed and they withdrew that in a written statement. Lee Harvey Oswald can have a gun but I can’t because I was born too late? I’m calling shenanigans on that.
If you are too stupid to figure out a solved problem then let it blow up in your face
Heh, this must be what my neighbours are doing whenever I try and catch a Meteor pass.
What an absolute MAD LAD!
What, no Rickroll?
Sadly, no.
Could we use it for something useful, like playing a lot of different digital video (tv) SD channels over an old cable input, to allow TVs that still have an analog input to actually be fun to change channels again?
An old Blonder-Tongue modulator would be easier for wired TV. A handful of RPi’s with composite out as your source.
” if you keep the power low enough so as not to broadcast anything beyond your home lab, it’s unlikely anyone will ever find out”
I’ll take the challenge of finding out.
using Taylor Swift is a crime against humanity.
On every FM frequency: “People Of Earth, prepare to be exterminated. The Vogons are going to destroy your planet to make way for a space superhighway…. Ah Douglas Adams…
Sorry, couldn’t resist, it was too good.
It would be most disturbing if you broadcast a different message, all similar though, on each station.
Otherwise the end user recieving the message is just as likely to think it’s a single strong signal overpowering their radio. A different message on each station and if they switch stations they’re going to be completely rocked by the results.
Since it works playing Taylor Swift…..it will be ready to broadcast on every channel Indian Love Song by Slim Whitman when Mars Attacks ! ack ack ack ack ack
if you get caught, say that you wanted to establish communication with an extraterrestrial civilization.
ufo is alvays good idea. sending information from eart to other galaxy
“Every FM channel at once” ? I’ve always held the view that radio has stations and TV has channels. Open a hailing
frequency Lieutenant.
Doctor.
Stations are broadcasters, and they broadcast on channels. Channels can be quiet and have no stations on them, depending on where you are.
A TV receiver has hard-wired hard-coded stations, 2,3,4,1095 and so forth. An AM/FM radio receiver such as in a home stereo does not. CB radio in the U.S. has similarly hard channels. The use of the term “clear channel” in the radio business is an unfortunate bit of confuseritation. It’s terminology, there’s no reason a TV receiver couldn’t have a channel 3 and a half. Or you could repaint the dial so each station is represented by its spirit animal. Again the difference is between hard-wired hard-coded stations of TV sets and the smooth groovy continuum of the radio dial. It’s simply the way things are organized.
Can this be done using HackRf?
Baby shark…