April 10th, 2005


Random information from the rpgnut

What sort of patterns do the scientists working on the search for extraterrestrial intelligence look for?

SETI scientists do not look for patterns but rather a lack of patterns in a signal. Although this may seem puzzling, it’s really a matter of physics. The first challenge facing any SETI project is detecting a signal against the background of cosmic and terrestrial noise. A signal containing a great deal of information will be spread across the spectrum more than a very simple signal containing little information would be. An "informative" signal will look more like random noise and thus will be harder to detect. So, in SETI, they look for very simple signals, ones that are easy to distinguish from astrophysical sources.
phoenix by katekat1010

Feels like an idiot...

Okay guys, maybe you can help me out here.

I've got a 433 MHz signal and need to find a 50 Ohm antenna. Reliable sources tell me the length of this antenna should be 17.3 cm, but I just can't get it to work out.

Here's where I'm at: lamda=c/f = (300 * 10^6 m/s)/(433 * 10^6 s^-1) = 0.69 m = 69 cm

Now as far as I know, the length of the antenna should then be half of the wavelength to produce a 50 ohm impedance. 1/2 of 69 cm is NOT 17.3 cm.

Anyone wanna tell me where I'm going wrong?