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

From: Seth David Schoen
Subject: [Discuss-gnuradio] VGA-based DVB-T modulator
Date: Mon, 13 Jun 2005 14:05:32 -0700
User-agent: Mutt/1.5.9i

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.

He uses a static greyscale image displayed under X11 with weird video
timings, and connects two of the VGA pins to a coax cable.

It generates a DVB-T signal on DVB-T channel 5 in VHF (around 176
MHz).  He has also produced PAL and SECAM VHF equivalents by the same

(via slashdot)

So it looks like you can use a VGA card as a source of arbitrary VHF
waveforms (at least arbitrary periodic VHF waveforms) without an
upconverter.  Bellard seems to think that you could use it to do
nonperiodic waveforms too.

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)

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