response 1 of 61:

Jun 9 20:00 UTC 1999

I am running seti@home on a 120 MHz PowerMac, which makes launching and
running the software for background computation rather slow down other
applications. However it can also be run as a "screensaver" - it kicks in
when the computer is idle, and picks up where it left off. However the
screensaver mode requires a display setting of at least 800x500 pixels,
and I prefer running at 640x480. The screensaver mode refuses to run
unless I change the display setting to 800x600. There is no reason why one
has to display the "screensaver" at all, however (you can have it go to a
dark screen). I would like to know if I can set the software to run in
"screensaver" mode with any display setting. The background mode will run
OK with any display setting. 

(I am asking here first as others may have solved this problem, before
I ask the very busy people at SETI.)

response 3 of 61:

Jun 10 05:12 UTC 1999

As I said in #1, that slows down other application when seti@home is
running in the background - quite seriously, on this machine. That's
why I want the screensaver *mode* but not the screensaver or its display. 
I'd like the machine to crunch the numbers when my machine is on and idle,
without having to change the display parameters. 

On another aspect of SETI@home - I read somewhere, and was told again
today, that when this effort was started they didn't have enough data
ready for the very large number of enrollees, so sent the same data sets
to large numbers of people. Does anyone have any more particulars on
that? I didn't see anything about it on the web site.

response 5 of 61:

Jun 11 04:23 UTC 1999

Sigh....my first work unit is only 19% done in 16 hours of CPU time. And,
there is no sign of ET.

response 7 of 61:

Jun 12 22:20 UTC 1999

I've heard that the fastest supported OS/CPU combo is Windows/Alpha.
Something like 9 hours a work unit.  (Must not do any graphics.)

response 9 of 61:

Jun 14 03:54 UTC 1999

Elementary SETI - continued.

That narrow-band (2.5 MHz) signal is downconverted to a lower frequency
and then digitized. It is then digitally subdivided into 256 sub-bands,
each 9766 Hz wide, and back converted to a digitally sampled time signal.
107 seconds of that 9766 Hz bandwidth signal constitutes a "work unit",
and is what is downloaded to your machine.

It takes 12 seconds for a stellar radio object to traverse the focus of
the Arecibo telescope and the signal strength received would look like
a Gaussian curve. This is what is looked for in the data. The problem
are:

1. The bandwidth of a signal transmitted by ETs is unknown.
2. The signal received is doppler shifted and degree of doppler shifting
   can be continually changing, because the source may be accelerating
   or decelerating along our line of sight as it (say) swings around a
   star.
3. The signal may be modulated. 

The data in a work unit are therefore analyzed *thousands of times*
assuming different bandwidths (starting at 0.07 Hz), different 
doppler accelerations (in steps of 0.002 Hz), and different pulse
rates (the assumed simplest modulation). 

The analyses are done with a technique known as Fast Fourier Transform
(FFT), which spreads out the 9766 Hz wide band and measures the power in
the chosen bandwidth intervals, for different time intervals in the 107
seconds of data. Each bandwidth interval power is fitted with a Gaussian
curve, and the quality of the fit is calculated and stored.

So far, one (1!) "highly" significant Gaussian signal has been detected in
all of the work units that have been done. They will go back and look
again, and also run tests to detect if it could have come from a
terrestrial source (terrestrial sources won't fade in and out with those
12 second reception windows).

The fastest computer/OS combinations do a work unit in ca. 9 hours of CPU
time. I'm up to about 37% of a work unit done in 37 hours of CPU time
(with a 120 MHz computer). It's been fun, but I think I better leave this
effort to faster machines. 

response 11 of 61:

Jun 15 03:39 UTC 1999

It might not be so much the operating system, as it is the software for
each particular operating system.

response 13 of 61:

Jun 16 15:17 UTC 1999

My work unit is now 56.5% complete - after 60.5 hours of CPU time. The
computation rolled over from positive to negative doppler accelerations
at the half way point. The doppler accelerations are, incidentally, called
the "chirping rate". It suddenly struck me why, as the doppler acceleration
is applied to the data - not to the spectral transform. That is, the
time-series data are "chirped" by transforming the time base. This would
make a single tone sound like, well, a "chirp". In cosmological terms,
the data are now being analyzed as though the source was accelerating
away from us, instead of toward us. 

One is struck by the idea that what is needed for analyzing these data
is a *brain*, not a computer. We are able to "hear" single notes of a
flute in the midst of all the sounds of an orchestra. Consider, though,
that what a microphone picks up from an orchestra is a single varying
voltage (or two such, if we do it in stereo). How would we go about
picking out just the chirp of a flute in that by means of a computer?

Perhaps it would be useful to also just listen to our 107 seconds of
10 kHz bandwith work-unit noise. 

response 15 of 61:

Jun 25 00:39 UTC 1999

I loaded SETI@home into our daughter's iMac, a G3 processor machine. This
did a work unit in 27 hours (while the PowerMac is still grinding away).

I'd like to suggest that GREX join the project. The program is available
for unix machines, and Grex is connected to the web, so it could
be automatic to start another work unit after finishing one. The
results for each work unit (as Gaussian power and chi-sqare "fit")
could be posted regularly. Grex might be the first to get a call from
ET! I do not know, however, how it would be set up to run in background
and not take a significant part of the overall CPU time. What do you
think?

response 17 of 61:

Jun 25 15:26 UTC 1999

They offer binaries for some 50 different unix and other systems.

response 19 of 61:

Nov 28 22:29 UTC 1999

That triggers an update - my daughter's iMac has now done 58 work units,
in between her homework. No strong gaussians have been found in these. 

response 21 of 61:

Jan 28 20:42 UTC 2002

They have something like three dozen signals that are being 
investigated more closely, last I heard.  There's a certain amount of 
work that has to be done 'by hand' to weed out interference from 
terrestrial sources and satellites, once most of the data has been 
discarded by the distributed analysis.

Right now they appear to be having server problems; my machine's been 
trying for about three days to return a work unit and download a new 
one, with no success.

I'm running SETI@home on my work computer, as a screensaver.  At home I 
was already running the distributed.net clients on both of my machines, 
when SETI@home started, and I've kept that up instead.  (RC5 
exclusively on the slower but always-on machine, a combination of RC5 
and OGR on the faster but not always on desktop.  OGR seems to be a lot 
more computationally intensive, and the slower machine just didn't make 
much progress on it.)

Is anyone participating in that distributed computing project to find a 
new anthrax drug?

response 23 of 61:

Jan 28 23:57 UTC 2002

The site's here: http://www.chem.ox.ac.uk/anthrax/

I'm not running it (no machines left with spare clock cycles!) so I 
don't really have enough information to start an item.