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SETI@Home Adds New Search Method
Adam Korbitz writes to point out that SETI@Home has added a new algorithm for use in evaluating signals from outer space. It's called "Astropulse," and they've made the scientific details available. Quoting:
"The original SETI@home is narrowband, meaning that it is listening for a particular radio frequency. That's like listening to an orchestra playing, and trying to hear when anyone plays the note "A sharp." Astropulse listens for short-time pulses. In the orchestra analogy, it's like listening for a quick drum beat, or a series of drumbeats. Since no one knows what extraterrestrial communications will 'sound like,' it seems like a good idea to search for several types of signals. In scientific terms, Astropulse is a sky survey that searches for microsecond transient radio pulses."
Isn't it the whole point of SETI@Home to use the normally unused cycles which you are already spending electricity and therefore money on?
The thing is that idle CPU time uses minimal electricity and generates minimal heat. The HLT command means that you're using less energy. This is particularly noticeable in laptops. Run something that uses 100% CPU time (SETI@home/video conversion/etc) and see how long your battery lasts compared to simply having the machine sit at idle (turn off screen saver and power management software).
While it's not huge on a minute to minute basis, the cost of power adds up over the course of a year. I found this out when I had a roommate that ran distributed computing software. When he moved out, our power bills dropped by about a third. In my opinion, that much money is not worth searching for intelligent life.
Not that kind of broadband - see the other meaning of broadband in telecommunications and signal processing
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No ressource was wasted. I suppose it takes more CPU cycles to check for both narrow and broad signals. The SETI project started by trying to have the lowest CPU usage possible and even by checking signals in a single wavelength in all the sky, it required the SETI@home project : touted as the biggest computation of all human history. Now they apparently are near completing their initial goal of checking for signals in the hydrogen wavelength, so they propose to use more power to check other forms of possible signals.
The Wise adapts himself to the world. The Fool adapts the world to himself. Therefore, all progress depends on the Fool.
Well, that's progress. I've criticized SETI@Home for looking for "carriers" signals with a large fixed-frequency component. They need to get beyond that. AM and FM signals have carriers (Analog TV is AM video with an FM audio subcarrier), and as a result, 80% of the signal energy is wasted. None of the more modern digital transmission systems have strong carriers.
The more efficient a transmission system, the more it looks like white noise if you don't know how to decode it. If there's some big repetitive component like a carrier, or the horizontal and vertical retrace intervals in analog TV, it's inefficient. The FCC wouldn't approve any new transmission system which wasted bandwidth like that, and the old ones that do are being phased out.
So SETI systems that look for carriers are looking for civilizations advanced enough to generate high-power RF signals, but not advanced enough to use more efficient digital modes. Our civilization went through that period in under a century. It's also fairly clear that nobody in our stellar neighborhood is continuously sending a strong RF carrier in our direction; that's been looked for.
Question: can the new SETI algorithm pick up an HDTV broadcast station?