Re: [Discuss-gnuradio] VGA-based DVB-T modulator

[Seth David Schoen]

Johnathan Corgan writes:

> Seth David Schoen wrote:
> 
> >Someone proposed this a while ago, but Fabrice Bellard (who is also
> >responsible for cool stuff like the tcc compiler, which lets you use
> >C as a scripting language and lets the Linux kernel compile itself
> >at boot time) has used a VGA card's DAC as an RF modulator to produce
> >a valid DVB-T signal.
> 
> I sure wish I could remember where to find it, but I've seen 
> demonstrated a program that would generate valid AM waveforms by 
> displaying certain pictures on a video screen.  You'd enter a target 
> frequency (I think in the HF range) and choose a MIDI sound file, and it 
> would "modulate" the CRT display to emit RFI at that frequency with the 
> tones riding as AM modulation.  Very spooky.  It was a demonstration of 
> the security hazards associated with CRT displays (TEMPEST stuff) in a 
> very palpable way.

Probably Tempest for Eliza:

http://www.erikyyy.de/tempest/

There's yet another similar project that I would like to track down
that was using a VGA card.

Does anyone here know if the VGA cards prevent you from controlling
the DAC durinng the blanking intervals?  Are the blanking intervals
implemented in hardware or in software?

-- 
Seth David Schoen <address@hidden> | Very frankly, I am opposed to people
     http://www.loyalty.org/~schoen/   | being programmed by others.
     http://vitanuova.loyalty.org/     |     -- Fred Rogers (1928-2003),
                                       |        464 U.S. 417, 445 (1984)