
Use RF noise from VGA DAC to drive VHF TV - luu
http://bellard.org/dvbt/
======
hammock
I remember reading articles in the 90's about the TEMPEST technology (or some
other name) where spy agencies could remotely eavesdrop on the output of your
computer monitor, without a line of sight, from a truck parked on the street.

Example: [http://www.sans.org/reading-
room/whitepapers/privacy/introdu...](http://www.sans.org/reading-
room/whitepapers/privacy/introduction-tempest-981)

~~~
porges
The general term for this (although a different concept to TFA) is
[http://en.wikipedia.org/wiki/Van_Eck_phreaking](http://en.wikipedia.org/wiki/Van_Eck_phreaking)
(as popularized in Cryptonomicon)

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elteto
I have a really cool story that I like to tell whenever something like this
comes up. When I was a kid we had a very old 386 PC with a gigantic black &
white CRT monitor, it was also _very_ heavy (at least for a little kid). The
computer was in a room adjacent to the living room where we had the TV and one
day we started noticing lines of snowy noise appearing on the image on the TV.
It seemed to be random and it was annoying as heck. One day I'm sitting on the
computer doing something in good old MS DOS and the door is open, so I can
work on the PC _and_ watch cartoons at the same time, so double win for me!!
It is then that I notice something really curious, the lines of noise on the
TV are identical in shape and pattern to the ones on my monitor!!! Whoa!! I
try writing long lines alternating with short ones and they also appear on the
TV, and even though you couldn't discern specific letters you could definitely
tell the spacing between the words. Mind blown!!! I think the culprit was in
the unshielded cable running from the antenna in our roof to the TV, which
happened to pass by the room with the computer in it. Anyway, I solved the
noise "mystery" that day, but was subsequently banned from using the computer
whenever the family was gathered watching TV. Talk about being ungrateful :)

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zxcvgm
On a similar note, the Raspberry Pi can be turned into a FM transmitter
without additional hardware [0]. I remembered seeing another hack for a higher
frequency that required a filter to be attached to the GPIO but I can't find
the link.

[0]
[http://www.icrobotics.co.uk/wiki/index.php/Turning_the_Raspb...](http://www.icrobotics.co.uk/wiki/index.php/Turning_the_Raspberry_Pi_Into_an_FM_Transmitter)

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ChuckMcM
There is an even better story about reading the screens of people using VGA
cards at a distance by post processing the emissions coming from them [1]. Of
course it is always fun to have your computer do things in interesting an
unexpected ways.

[1]
[http://www.eskimo.com/~joelm/tempest.html](http://www.eskimo.com/~joelm/tempest.html)
used to be a page that had links to code that was used for reconstructing a
vga image on your screen from picking up passive radiation, it has sadly gone
away.

~~~
shabble
I think
[http://www.jammed.com/~jwa/tempest.html](http://www.jammed.com/~jwa/tempest.html)
might be the same FAQ/info page (right author, anyway), although last updated
in '99, and no obvious links to any code (except one link about sniffing CPU
emissions, which is also bitrotted)

~~~
mentat
Playing music using monitor emissions:
[http://www.erikyyy.de/tempest/](http://www.erikyyy.de/tempest/)

~~~
minikomi
See also the Braun Tube Jazz Ensemble
[http://youtu.be/Ouue59iY0Hs](http://youtu.be/Ouue59iY0Hs)

~~~
nitrogen
This is interesting. I wish I understood what was going on. YouTube's
automatic translated captions were little help.

~~~
minikomi
He has guitar leads on his hands, and preset loops playing on each tv - for
example, drum samples, tones - recorded on VHS. The audio is recorded as the
video signal. Then, by putting his hands near the front of a television, the
video signal is picked up by the guitar lead and played through the amplifier.
He can play it by selecting which sample to play when.

Another video of him playing:
[http://www.youtube.com/watch?v=v5T2Q_wgoKg](http://www.youtube.com/watch?v=v5T2Q_wgoKg)

And a video of his other project, Open Reel Ensemble:
[http://www.youtube.com/watch?v=AFM8UarAuVw](http://www.youtube.com/watch?v=AFM8UarAuVw)

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Swannie
This guy never ceases to amaze.

Allez Fabrice!

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awda
Fabrice Bellard, what a tease. Lots of awesome engineering work, no source
code =(.

~~~
hwh
Well, not entirely fair. QEmu is open source.

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nsxwolf
Music played on a radio made from the RF emissions of the IBM 1401:

[http://youtu.be/EPk8MVEmiTI](http://youtu.be/EPk8MVEmiTI)

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tomrod
Guys, this is some of the coolest stuff I've ever seen. _These_ are the
articles that keep me coming back to Hacker News.

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nitrogen
Take a look at the .pgm images that generate those RF signals. I imagine
that's the best we could hope to see leaking from some interstellar
civilization's communications.

