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System Bus Radio: Transmits AM radio on computers without transmitting hardware

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Re: System Bus Radio: Transmits AM radio on computers without transmitting hardware

#41

Post by j_s »

BuildTheRobots wrote: post #22

There's also PiFM[1] which (iirc) modulates one of the GPIO pins fast enough on a Pi to produce an FM radio signal. It's fun to play with, and is a great hack, but please don't try and use it for anything or any length of time; it puts out a tonne of horrible harmonics all over the radio spectrum. [1] https://github.com/rm-hull/pifm

Or take the rails completely off (5 KHz-500 MHz // FM,AM,SSB,SSTV,FSQ): https://github.com/F5OEO/rpitx

I have a „Hörmann“ garage door opener. For a long time, I want to use my phone instead of the original sender. Therefore, I thought to run a raspberry and send the signal from there.

I recorded the signal with HackRF One as .wav, the problem here is that HackRF records with a sampling rate much higher than 48kHz (by default it is 10MHz!). So one has to downsample the recorded file, which I did with Matlab (downsample(signal, „fs_of_record/fs_for_rpitx“)). The resulting .wav signal is now send at 433MHz (either my garage door listens their too, or 2nd harmonic works?!)

src: https://github.com/F5OEO/rpitx/issues/50

Re: System Bus Radio: Transmits AM radio on computers without transmitting hardware

#42

Post by inetknght »

zenkat wrote: post #13
Zenst wrote: post #3

Earlier quoted context omitted.

Computers emit radio waves, by varying the processing upon the computer you can influence those emissions. Thus you are able to control those emissions and produce a radio signal you can pick up upon a standard radio.

What part of the computer is emitting the radiation? And how is this program manipulating it to generate a song?

Any wire acts as an antenna. Therefore, any part of the computer can be the part emitting the radiation.

Choosing which part of the computer is a matter of choosing the frequency which dictates the length of wire necessary and which parts can oscillate at that frequency.

Re: System Bus Radio: Transmits AM radio on computers without transmitting hardware

#43

Post by beamatronic »

dsign wrote: post #34

People had fanciful minds. They had expected the civilization to end in bio-warfare, or atomic bombs, or a blazing meteorite impact. No such luck. The end of the civilization came, rather anticlimactically, when the humans discovered that side effects and timing attacks made any form of cyber-security a joke. Their computers screeched to a halt bogged down by nightmarish security patches. By then, it was already too…

Or they just went back to using simple CPUs, and were content with solving smaller problems.

Re: System Bus Radio: Transmits AM radio on computers without transmitting hardware

#44

Post by netsharc »

gtufano wrote: post #40
cestith wrote: post #35

Back a couple of decades, my alphabetic pager was going off but the messages were gibberish. It turned out the CPU in the PC I'd been asked to look at was a Pentium running at 150 MHz. I'd set my pager directly on top of the case, and the nominal frequency for it was 150.5 MHz, frequency modulated. The lines in the motherboard can be used as antennae and the CPU pins can produce a clock pulse and modulate it. There u…

Years ago I was in the same building during the installation of a "NATO standard" (whatever that means) environment suitable for developing sensitive software, and the air gap was indeed pretty large, the entire 2 rooms were air gapped from the building (at 4th floor), enclosed in a Faraday cage and with special precautions (out of my clearance level) for electricity going in. It was very quiet inside (even cell phon…

Hopefully cellphones weren't allowed? Otherwise it would be interesting to hack the phone to go to "record AM signals" if there's no cell/wifi/FM/GPS signals (if it were on a plane it would still see GPS signals). Or maybe to announce its presence using ultrasonic, so if there's also compromised machines/CPUs/hypervisor environments inside the secured environment, it would detect the "Hello" and start uploading data to it. Later when the phone user reconnects to the cell network, it can upload your secret data..

Re: System Bus Radio: Transmits AM radio on computers without transmitting hardware

#45

Post by beamatronic »

TomV1971 wrote: post #28

Tangentially related: the singing Commodore 64 floppy drive. https://m.youtube.com/watch?v=5gnMgmlKi_o

I remember that! I believe it did some small amount of damage to the drive. Head needed to be realigned or such.

Re: System Bus Radio: Transmits AM radio on computers without transmitting hardware

#46

Post by z3t4 »

kabdib wrote: post #21

I debugged a boot issue on the Apple Newton this way. The latest flash image was a brick on production hardware (no available LEDs, GPIOs, etc.) but not on development hardware. But I could flash a new OS image. So I wrote some small loops that did different stuff on the bus (so that they sounded different) and salted the boot path with them, then listened in on my portable AM radio. Found the problem inside of an ho…

meanwhile on the web: "The undefined variable foo on line 13 is not a function"

Re: System Bus Radio: Transmits AM radio on computers without transmitting hardware

#47

Post by baq »

samfisher83 wrote: post #29
baq wrote: post #20

side channel information leak for two, please

This is how you debug hardware.You put a oscilloscope on the bus and you decode the bytes. This is what people have been doing since the advent of the computer.

'on the bus' is quite a bit different from '1 meter of drywall away' though...

Re: System Bus Radio: Transmits AM radio on computers without transmitting hardware

#48

Post by dsign »

beamatronic wrote: post #43
dsign wrote: post #34

People had fanciful minds. They had expected the civilization to end in bio-warfare, or atomic bombs, or a blazing meteorite impact. No such luck. The end of the civilization came, rather anticlimactically, when the humans discovered that side effects and timing attacks made any form of cyber-security a joke. Their computers screeched to a halt bogged down by nightmarish security patches. By then, it was already too…

Or they just went back to using simple CPUs, and were content with solving smaller problems.

... they were all eagerly awaiting to upload their souls to Intel CPUs, but alas ...

Re: System Bus Radio: Transmits AM radio on computers without transmitting hardware

#49

Post by cadr »

j_s wrote: post #41
BuildTheRobots wrote: post #22

There's also PiFM[1] which (iirc) modulates one of the GPIO pins fast enough on a Pi to produce an FM radio signal. It's fun to play with, and is a great hack, but please don't try and use it for anything or any length of time; it puts out a tonne of horrible harmonics all over the radio spectrum. [1] https://github.com/rm-hull/pifm

Or take the rails completely off (5 KHz-500 MHz // FM,AM,SSB,SSTV,FSQ): https://github.com/F5OEO/rpitx I have a „Hörmann“ garage door opener. For a long time, I want to use my phone instead of the original sender. Therefore, I thought to run a raspberry and send the signal from there. I recorded the signal with HackRF One as .wav, the problem here is that HackRF records with a sampling rate much higher than 48kHz (by…

For a really good time, I suggest https://github.com/JamesP6000/WsprryPi - it is super fun run a signal into a long wire and see it picked up around the world!

(You do need an amateur radio license for this, but in the USA at least the technician one is very easy to get.)

Re: System Bus Radio: Transmits AM radio on computers without transmitting hardware

#50

Post by vidarh »

beamatronic wrote: post #45
TomV1971 wrote: post #28

Tangentially related: the singing Commodore 64 floppy drive. https://m.youtube.com/watch?v=5gnMgmlKi_o

I remember that! I believe it did some small amount of damage to the drive. Head needed to be realigned or such.

You're right. It works because there's no protection against trying to send the drive head past where it's meant to be able to go, because nobody expected anyone would try to repeatedly ask it to move out of bounds, and the vibration can easily get the head out of alignment.
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