very low frequency tech postings - 25 04 2003
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Fri, 25 Apr 2003
das clock fake 77
'das clock fake 77' is a radio transmitter.
This program paints black and white stripes on your screen. Your monitor
will now emit electromagnetic waves. Basically a carrier frequency of
77500 Hz. In Europe commonly used DCF77-radio-clocks will tune into that
frequency and listen ... to be honest, only if they're close enough to
your monitor they may/might.
The screen image will be modulated to emit the 59 information bits plus
the one sync bit per minute. Actually we only need to switch between two
static images once per second, but with a high timing precision of about
50ms. Nothing evil will happen to your monitor or LCD, we're not playing
with your modelines or the sync of your monitor.
The program uses the SDL-library to acess the screen, this can be a
problem when you don't have HW-acceleration - I had to switch back to
16bpp on my X to get the required 20fps.
The program now tests wether the screen performance is sufficient to
achieve the required 20 fps.
See the README for more details. Get it here.
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