This HTML version of the FAQ is based on the original TEXT version. Updates will usually follow within a week after a new TEXT version has been published. index SETI@home FAQ V3.0.10 09 November 2003 for newsgroups alt.sci.seti and sci.astro.seti FAQ Home : http://setifaq.org/ Text-only : http://setifaq.org/faq.txt Html-version: http://setifaq.org/faq.html Anon. FTP : ftp://setifaq.org/faq.txt FAQ Home : http://www.setifaq.org/ Text-only : http://www.setifaq.org/faq.txt Html-version: http://www.setifaq.org/faq.html http://www.setifaq.org/charter-alt-sci-seti.html http://www.setifaq.org/charter-sci-astro-seti.html Free Ringtones Free Ringtones To save this FAQ on you local drive click File/Save on your browser or newsreader and choose the location where you wish it saved. Those listed with e-mail addresses are also listed with sections for which they are working on. If you want to supply any input to these sections, e-mail them and put CC to Mark Taylor. Authors Author : Mark Taylor <maintainer@setifaq.org> Html-version: Alfred Das Contributors: SETI@home team, Peter Alfredsen, Frank J. Perricone, Mark Stilgar, Arthur Schain, Ed H, Neil Rieck, Thomas Martin, Malcolm Pack, James Birchfield, Roelof Engelbrecht, Allen Cleveland, Chris Johnson, Carl Sagan, Eric J. Korpela, Terry Lee, Sqiz, David Woolley, Jan Knutar, Peter van der Kort, David Schilling, Alfred Das, Peter Yackel, Lior Fainshil, Eric Heien, John Pike, Steve Willner, Alfred A. Aburto Jr. Comments from the Author Don't hesitate to contact me if you see something in the FAQ that you think is wrong. Suggestions, comments, additions, corrections, etc are more than welcomed . I'll reply to every email so that you'll know if your addition/correction will be included and if not, why. People who contribute to the FAQ will be given credit if they wish so. This latest version of the FAQ increases to version 3.0.0 to match the current major version of the Seti@home Client. Sincerely Mark Taylor <maintainer@setifaq.org> Legal Chit-chat This document is subject to copyright. It may be copied, distributed, and otherwise electronically transferred, if you agree to the following terms: 1. If made publicly available, it must be updated regularly, hereby meaning every 30 days. 2. You agree, if making publicly available this document, or parts hereof, to link to the official FAQ-pages: http://setifaq.org/ http://setifaq.org/faq.txt http://setifaq.org/faq.html ftp://setifaq.org/faq.txt 3. It would be preferred, if you want to copy this FAQ, that you notify the author. Further information for mirroring the html FAQ is available as html comments in the html-version. top 0 INDEX 1 http://setifaq.org/faq.html#1 1.1 http://setifaq.org/faq.html#1.1 1.2 Background 1.2.1 The Drake Equation 1.2.2 The Fermi paradox 1.2.3 How far away could we detect radio transmissions? 1.2.4 The quest for EXTRATERRESTRIAL INTELLIGENCE 1.2.5 http://setifaq.org/faq.html#1.2.5 1.2.6 What is a Gaussian? 1.2.7 http://setifaq.org/faq.html#1.2.7 1.2.8 What are pulses and triplets? 1.3 The history and customs of alt.sci.seti and sci.astro 1.3.1 Charter for alt.sci.seti 1.3.2 Charter for sci.astro.seti 1.3.3 Naming convention 1.3.4 .sig convention 1.3.5 Labeling posts 1.3.6 http://setifaq.org/faq.html#1.3.6 1.3.7 What is a 'vcard' and why do people tell me not to use them? 1.3.8 What is PST and PDT? 1.4 What will happen if an extraterrestrial signal is detected? 1.5 How is data collected from the telescope and transmitted to other machines for analysis? 1.6 Consolidate Debt loans 1.7 What if my computer finds a signal -- how will I know? 1.8 How can I hear the signal? 1.9 Is there something in it for me? 1.10 http://setifaq.org/faq.html#1.10 2 http://setifaq.org/faq.html#2 2.1 Speed improvements 2.1.1 What's the fastest computer to use for this project? 2.1.2 Can I make it run any faster? 2.1.3 REMOVED March 2000, was: http://setifaq.org/faq.html#2.1.3 2.1.4 http://setifaq.org/faq.html#2.1.4 128 MB)? 2.2 REMOVED April 2000, was: I'm using a proxy server, and I can't connect - what do I do? 2.3 I had a work unit that got returned after only 5 minutes. What's wrong? 2.4 I heard I was getting the same work unit as everyone else. Is the program wasting my time? 2.5 http://setifaq.org/faq.html#2.5 couldn't connect or reported error 10065. Are they still there? 2.6 What if someone fakes a result to make it seem like they found a signal? 2.7 http://setifaq.org/faq.html#2.7 2.8 Suddenly, without warning my system crashes - what should I do? 2.9 I can't see the new WU's I've processed in the status area. Have http://setifaq.org/faq.html#2.9 2.10 I want to run the text-client as a service in NT - how do I do that? 2.11 Can I run the client invisibly on Win95/98? 2.12 Sometimes the size of the workunit.txt file differs in size. Sometimes it's 340, sometimes 341, and yet other times 351. Isthere something wrong? 2.13 I don't have a permanent Internet connection, and have to pay http://setifaq.org/faq.html#2.13 without going bankrupt? 2.14 I already run the distributed.net RC5-64 client. Can I run http://setifaq.org/faq.html#2.14 support? 2.15 What happened to the gaussian information display in the new Mac and Windows clients? The client is finding gaussians with lower fits, do the 2.x clients find more aliens or something? 2.16 http://setifaq.org/faq.html#2.16 connection? 2.17 Is this bad for my processor, or my harddrive? 2.18 Does it use up a lot of electricity? Is this costing me money, or doing damage to the environment? 2.19 How can I keep appraised of what's going on lately? 2.20 General CL client issues 2.20.1 What is the CL client? 2.20.2 What CL options are there? 2.20.3 HELP, it stops at baseline smoothing!!! 2.20.4 How can I check up on the client to see how it's doing, if it has found any signals, etc? 2.20.5 How do I tell the CL client to use a proxy? 2.20.6 I just found a bug in the -stop_after_ switches!!!2.21 Running the CL client on Windows 2.21.1 What client should I download for Windows 95/98/2000/NT? 2.21.1.1 2.21.2 How do I start it? 2.21.3 How do I stop it? 2.21.4 How do I make Windows 2000 autoconnect? 2.21.5 Do I have to uninstall the screen saver version if I use the CL version? 2.22 http://setifaq.org/faq.html#2.22 client 2.22.1 What client should I download? 2.22.2 How do I uncompress the .tar file? 2.22.3 How do I start it? 2.22.4 How do I stop it? 2.22.5 How can I run it in the background rather than in a window? 2.22.6 How can I have it automatically restart if it dies? 2.22.7 What is 'nice' and how do I set it? 2.23 Why does the client timeout before windows has dialed up my ISP? 2.24 this good? 2.25 http://setifaq.org/faq.html#2.25 the top gaussian I got for the last unit is missing, why? 2.26 My email address is about to change, what do I do? 2.27 RE-ORDERED 5 Oct 2000, to: 2.30 2.28 Why does the new client (3.X) take more time to complete a WU? 2.29 What are pulses and triplets? 2.30 What is an interesting pulse/triplet? 2.31 Why do certain WU's take longer to process? 2.32 Why are the most pulse searches done at a chirp rate of 0? 2.33 There's something strange with the power reported on pulses in outfile.sah vs. state.sah? 2.34 Is the first half of the pulse graph identical to the second? 3 Third-party software 3.1 JSETITracker 3.1.1 Programmer's comments 3.2 http://setifaq.org/faq.html#3.2 3.2.1 Programmer's comments 3.2.2 http://setifaq.org/faq.html#3.2.2 3.2.3 http://setifaq.org/faq.html#3.2.3 3.3 SETI Spy 3.3.1 Programmer's comments 3.3.2 Processing efficiency 3.4 SETIWatch 3.4.1 What is SETIWatch? 3.4.2 Some background 3.4.3 Where can I get it? 3.4.4 How to install SETIWatch 3.5 SETILog 3.5.1 What is SETILog? 3.5.2 How does SETILog work? 3.5.3 RunSETI.bat 3.5.4 Where can I get it? 3.5.5 How to Install SETILog 3.6 SetiTEAM 3.6.1 Description 3.7 SETIBuf 3.7.1 Legal notice and stuff 3.7.2 General description 3.7.3 Where can I get it? 3.8 SETI Monitor 3.8.1 Description 3.8.2 Some more details 3.8.3 Where can I get it? 3.9 SETI 3.9.1 About SUM 3.9.2 Cost 3.9.3 Requirements 3.9.4 Where can I get it? 3.10 Setimgr 3.10.1 Programmer's comments 3.10.2 Setup 3.10.3 Operation 3.11 Seti4Net 3.12 http://setifaq.org/faq.html#3.12 4 Homepages 4.1 http://setifaq.org/faq.html#4.1 4.1.1 http://setifaq.org/faq.html#4.1.1 4.1.2 SETIweb 4.1.3 SETIforum 4.1.4 http://setifaq.org/faq.html#4.1.4 4.1.5 http://setifaq.org/faq.html#4.1.5 4.1.6 http://setifaq.org/faq.html#4.1.6 4.1.7 SETI STATION 4.1.8 SETI: The Drake Equation 4.1.9 Sci.astro FAQ about SETI 4.1.10 Team Canada 4.1.11 The Planetary Society 4.1.12 Patch-free-Processing 4.1.13 Sky & Telescope 4.1.14 SETI Institute 4.1.15 SETI League 4.1.16 REMOVED 11 Feb 2001, was: SETI & Beyond 4.2 SETI utilities 4.2.1 SETIwatch & SETIlog 4.2.2 SETI Manager 4.2.3 http://setifaq.org/faq.html#4.2.3 4.2.4 SETISPY 4.2.5 JSETITracker 4.2.6 SetiTEAM Homepage 4.2.7 SETIBuf homepage 4.2.8 SETI Monitor homepage 4.2.9 SETI UNiT Manager homepage 4.2.10 RunCache & FetchCache 4.2.11 http://setifaq.org/faq.html#4.2.11 4.3 SETI fun 4.3.1 Carolyn's Clinic 5 Acknowledgements 5.1 Sci.astro FAQ 5.2 People who have worked with the FAQ top index 1 About SETI@home 1.1 What is SETI/SETI@home? If we assume that our alien neighbors are trying to contact us, we should be looking for them. There are currently several programs that are now looking for the evidence of life elsewhere in the cosmos. Collectively, these programs are called SETI (the Search for Extra-Terrestrial Intelligence.) http://setiathome.berkeley.edu/ is a scientific experiment that harnesses the power of hundreds of thousands of Internet-connected computers in the Search for Extraterrestrial Intelligence (SETI). You can participate by running a free program that downloads and analyzes radio telescope data. There's a small but captivating possibility that your computer will detect the faint murmur of a civilization beyond Earth. index 1 1.1 1.2 Background 1.2.1 The Drake Equation <This is only one possible guess at, how the Drake Equation may be. If you want to guess for yourself, look under 4.1.8 SETI: The Drake Equation> Our sun is only a single star in a collection of over 400 billion we call the Milky Way galaxy. The Milky Way is only 1 of billions of galaxies in the universe. Seems like there should be lots of life out there! Can we make an initial estimate? The first to do so was the astronomer Frank Drake. He came up with a simple equation, now called the Drake Equation, that maps out the possibilities. The equation is quite easy to understand, so don't tune out, even if arithmetic isn't your strong suit! Here it is: N = R * f(p) * n(e) * f(l) * f(i) * f(c) * L "N" here represents the number of communicating civilizations in our Milky Way galaxy. This number depends on several factors. "R" is the rate of "suitable" star formation in the galaxy. "f(p)" is the fraction of stars that have planets. "n(e)" is the number of these planets around any star within the suitable ecosphere of the star. An "ecosphere" is a shell that surrounds a star within which the conditions are suitable for life to form. Too close and it's too hot; too far and it's too cold. "f(l)" is the fraction of those planets within the ecosphere on which life actually evolves. "f(i)" is the fraction of those planets on which intelligent life evolves. "f(c)" is the fraction of those planets where intelligent life develops a technology and attempts communication. "L," is the length of time that an intelligent, communicating civilization lasts. Let's briefly look at each of these factors separately and try to put some reasonable numbers to them. Although the rate of suitable star formation was undoubtedly much higher when our galaxy formed, one can still see where stars are being born today. In the last couple of years, several teams of astronomers have announced the discovery of planets surrounding nearby stars. This exciting discovery increases the likelihood of other planets around many stars. Let's estimate conservatively that one-half of the stars form planetary systems; the other half form binary star systems, so f(p) = 0.5. The n(e) factor is a little tricky. Small stars are cool and red. Planets would have to orbit very close to be in the ecosphere. Also, this ecosphere would be very narrow; like the skin on an orange. Not much room for planets. Planets that orbit very close to their parent star are often tidally locked and present one face to the star at all times. The atmosphere of such a planet would freeze on the cool side that faces away from the star; this does not promote life. On the other hand, huge hot blue stars have a farther and wider ecosphere. Of course, judging from our solar system, planets are spaced further apart the farther they are from the star, so the wider ecosphere is cancelled by this effect. These larger stars also burn their fuel faster and don't last very long. They are usually so short- lived that life does not even get a chance to start before the star goes nova or supernova and destroys everything in the system. In our solar system, with our average-sized yellow sun, we have two (Earth and Mars) or maybe three (Venus) planets within the ecosphere. A conservative guess for the number of planets within the "life zone" or ecosphere is one. n(e) = 1. The next factor, f(l), is where things become a little sticky. The problem is that we only have a few examples of planets where conditions are right for life to evolve. As stated above, Venus, Earth, and Mars all could have had, at one time, proper conditions. We know life evolved on Earth, and there is now tantalizing evidence for primitive life existing on Mars billions of years ago. A conservative guess for this number is 0.2, or one in five planets with proper conditions will evolve life. f(l) = 0.2. How many of these planets will evolve intelligent life? Tough question, but if we really believe the evidence for natural selection and survival of the fittest, most scientists would put this number at 100 percent -- that intelligent life is a natural outcome of evolution. Of course, here we have only one example, earth. f(i) = 1. How many of these intelligent species will develop technology and use it to communicate? If we look at the earth, we see humans doing it, but we also see whales and dolphins, who may also possess a moderate level of intelligence but never developed technology. We'll set this number to 0.5 as a first guess. f(c) = 0.5. Now we get to the hardest number to determine. "L" is the number of years that a technologically adept and communicative civilization lasts. We've only been in this phase of our evolution for about 50 years. Do advanced civilizations blow themselves up after discovering the technology to do so? Or do they get together and solve their problems before this happens? For now, let's not assign a number to L. Let's plug in the other numbers and see what we get. N = R * f(p) * n(e) * f(l) * f(i) * f(c) * L N = 20 * 0.5 * 1 * 0.2 * 1 * 0.5 * L Do advanced civilizations use their technology to solve their problems or do they destroy themselves? On earth we've survived the first 50 years. Multiplying all the numbers gives us N = L. In other words, the number of intelligent communicating civilizations in the galaxy equals the number of years such a civilization lasts! The figure about which we know the least bears a great significance in our calculations. Most scientists hope that if a civilization can overcome its initial tendency to destroy itself with its own technology, then that civilization is likely to last for a very long time. Let's hope those scientists are right. In any case, there should be at least 50 (the number of years WE'VE been around communicating) and if a communicative civilization lasts for millions of years, there may possibly be millions of civilizations we can look for. index 1 1.2 1.2.1 1.2.2 The Fermi paradox By John Pike and Steve Willner One of the problems that the Drake Equation produces is that if you take reasonable (some would say optimistic) numbers for everything up to the average duration of technological civilizations, then you are left with three possibilities: 1. If such civilizations last a long time, "They" should be _here_ (leading either the the Flying Saucer hypothesis--they are here and we are seeing them, or the Zoo Hypothesis--they are here and are hiding in obedience to the Prime Directive, which they observe with far greater fiqdelity than Captain Kirk could ever muster). -or- 2. If such civilizations last a long time, and "They" are not "here" then it becomes necessary to explain why each and every technological civilization has consistently chosen not to build starships. The first civilization to build starships would spread across the entire Galaxy on a timescale that is short relative to the age of the Galaxy. Perhaps they lose interest in space flight and building starships because they are spending all their time surfing the net. (Think about it --- the whole point of space flight is the proposition that there are privileged spatial locations, and the whole point of the net is that physical location is more or less irrelevant.) -or- 3. Such civilizations do not last a long time, and blow themselves up or otherwise fall apart pretty quickly (... film at 11). Thus the Drake Equation produces what is called the Fermi Paradox (i.e., "Where are They?"), in that the implications of #3 and #2 are not terribly encouraging to some folks, but the two flavors of #1 are kinda hard to come to grips with. An alternate version of 2 is that interstellar travel is far more difficult than we think it is. Right now, it doesn't seem much beyond the boundaries of current technology to launch "generation ships," which amount to an O'Neill colony plus propulsion and power systems. An alternative is robot probes with artificial intelligence; these don't seem so difficult either. The Milky Way galaxy is well under 10^5 light years in diameter and over 10^9 years old, so even travel beginning fairly recently in Galactic history and proceeding well under the speed of light ought to have filled the Galaxy by now. (Travel very near the speed of light still seems very hard, but such high speed isn't necessary to fill the Galaxy with life.) The paradox, then, is that we don't observe evidence of anybody besides us. index 1 1.2 1.2.2 1.2.3 How far away could we detect radio transmissions? By Al Aburto and David Woolley Representative results are presented in Tables 1 and 2. The short answer is (1) Detection of broadband signals from Earth such as AM radio, FM radio, and television picture and sound would be extremely difficult even at a fraction of a light-year distant from the Sun. For example, a TV picture having 5 MHz of bandwidth and 5 MWatts of power could not be detected beyond the solar system even with a radio telescope with 100 times the sensitivity of the 305 meter diameter Arecibo telescope. (2) Detection of narrowband signals is more resonable out to thousands of light-years distance from the Sun depending on the transmitter's transmitting power and the receiving antenna size. (3) Instruments such as the Arecibo radio telescope could detect narrowband signals originating thousands of light-years from the Sun. (4) A well-designed 12 ft diameter amateur radio telescope could detect narrowband signals from 1 to 100 light-years distance assuming the transmitting power of the transmitter is in the terawatt range. What follows is a basic example for the estimation of radio and microwave detection ranges of interest to SETI. Minimum signal processing is assumed. For example an FFT can be used in the narrowband case and a bandpass filter in the broadband case (with center frequency at the right place of course). In addition it is assumed that the bandwidth of the receiver (Br) is constrained such that it is greater than or equal to the bandwidth of the transmitted signal (Bt) (that is, Br >= Bt). Assume a power Pt (watts) in bandwidth Bt (Hz) radiated isotropically. At a distance of R (meters), this power will be uniformly distributed (reduced) over a sphere of area: 4 * pi * R^2. The amount of this power received by an antenna of effective area Aer with bandwidth Br (Hz), where Br >= Bt, is therefore: Pr = Aer * (Pt / (4 * pi * R^2)) If the transmitting antenna is directive (that is, most of the available power is concentrated into a narrow beam) with power gain Gt in the desired direction then: Pr = Aer * ((Pt * Gt) / (4 * pi * R^2)) The antenna gain G (Gt for transmitting antenna) is given by the following expression. (The receiving antenna has a similar expression for its gain, but the receiving antenna's gain is not used explicitly in the range equation. Only the effective area, Aer, intercepting the radiated energy at range R is required.) Gt = Aet * (4 * pi / (w^2)), where Aet = effective area of the transmitting antenna (m^2), and w = wavelength (m) the antenna is tuned to. f = c / w, where f is the frequency and c is the speed of light. c = 2.99792458E+08 (m/sec) pi = 3.141592654... For an antenna (either transmiting or receiving) with circular apertures: Ae = <eta> * pi * d^2 / 4 <eta>r = efficiency of the antenna, d = diameter (m) of the antenna. The Nyquist noise, Pn, is given by: Pn = k * Tsys * Br, where k = Boltzmann's constant = 1.38054E-23 (joule/kelvin) Tsys = is the system temperature (kelvins), and Br = the receiver bandwidth (hertz). The signal-to-noise ratio, snr, is given by: snr = Pr / Pn. If we average the output for a time t, in order to reduce the variance of the noise, then one can improve the snr by a factor of sqrt(Br * t). Thus: snr = Pr * sqrt(Br * t) / Pn. The factor Br*t is called the "time bandwidth product," of the receive processing in this case, which we'll designate as: twp = Br * t. We'll designate the integration or averaging gain as: twc = sqrt(twp). Integration of the data (which means: twp = Br * t > 1, or t > (1 / Br) ) makes sense for unmodulated "CW" signals that are relatively stable over time in a relatively stationary (steady) noise field. On the other hand, integration of the data does not make sense for time-varying signals since this woul information content of the signal. Thus for a modulated signal twp = Br * t = 1 is appropriate. In any case the snr can be rewritten as: snr = (Pt * Gt) * Aer * twc / (4 * pi * R^2 * Br * k * Tsys) Pt * Gt is called the Effective Isotropic Radiated Power (EIRP) in the transmitted signal of bandwidth Bt. So: EIRP = Pt * Gt, and snr = EIRP * Aer * twc / (4 * pi * R^2 * Br * k * Tsys) This is a basic equation that one can use to estimate SETI detection ranges. ####################################################################### # If Rl is the number of meters in a light year (9.46E+15 [m/LY]), # # then the detection range in light years is given by # # # # R = sqrt[ EIRP * Aer * twc / (4 * pi * snr * Br * k * Tsys) ] / Rl # # # # If we wanted the range in Astronomical Units then replace Rl # # with Ra = 1.496E+11 (m/AU). # ####################################################################### Note that for maximum detection range (R) one would want the transmit power (EIRP), the area of the receive antenna (Aer), and the time bandwidth product (twp) to be as big as possible. In addition one would want the snr, the receiver bandwidth (Br), and thus transmit signal bandwidth (Bt), and the receive system temperature (Tsys) to be as small as possible. (There is a minor technical complication here. Interstellar space contains a plasma. Its effects on a propagating radio wave including broadening the bandwidth of the signal. This effect was first calculated by Drake & Helou and later by Cordes & Lazio. The magnitude of the effect is direction, distance, and frequency dependent, but for most lines of sight through the Milky Way a typical value might be 0.1 Hz at a frequency of 1000 MHz. Thus, bandwidths much below this value are unnecessary because there will be few, if any, signals with narrower bandwidths.) Now we are in a position to carry out some simple estimates of detection range. These are shown in Table 1 for a variety of radio transmitters. We'll assume the receiver is similar to Arecibo, with diameter dr = 305 m and an efficiency of 50% (r = 0.5). We'll assume snr = 25 is required for detection (The META project used a snr of 27--33 and SETI@home uses 22; more refined signal processing might yield increased detection ranges by a factor of 2 over those shown in the Table 1.) We'll also assume that twp = Br * Tr = 1. An "educated" guess for some of the parameter values, Tsys in particular, was taken as indicated by the question marks in the table. As a reference note that Jupiter is 5.2 AU from the Sun and Pluto 39.4 AU, while the nearest star to the Sun is 4.3 LY away. Also any signal attenuation due to the Earth's atmosphere and ionosphere have been ignored; AM radio, for example, from Earth, is trapped within the ionosphere. The receive antenna area, Aer, is Aer = <eta>r * pi * dr^2 / 4 = 36.5E3 m^2. (Scientific notation is being used here; 1E1 = 10, 1E2 = 100, 1E3 = 1000, so 36.5E3 is 36.5 times 1000.) Hence the detection range (light years) becomes R = 3.07E-04 * sqrt[ EIRP / (Br * Tsys) ]. Table 1 Detection ranges of various EM emissions from Earth and the Pioneer spacecraft assuming a 305 meter diameter circular aperture receive antenna, similar to the Arecibo radio telescope. Assuming snr = 25, twp = Br * Tr = 1, <eta>r = 0.5, and dr = 305 meters. -------------+------- Source | Frequency | Bandwidth | Tsys | EIRP | Detection | | Range | (Br) |(Kelvin)| | Range (R) | -------------+--------------+-----------+--------+--------+-----------+ AM Radio | 530-1605 kHz | 10 kHz | 68E6 | 100 KW | 0.007 AU | -------------+--------------+-----------+--------+--------+-----------+ FM Radio | 88-108 MHz | 150 kHz | 430 | 5 MW | 5.4 AU | -------------+--------------+-----------+--------+--------+-----------+ UHF TV | 470-806 MHz | 6 MHz | 50 ? | 5 MW | 2.5 AU | Picture | | | | | | -------------+--------------+-----------+--------+--------+-----------+ UHF TV | 470-806 MHz | 0.1 Hz | 50 ? | 5 MW | 0.3 LY | Carrier | | | | | | -------------+--------------+-----------+--------+--------+-----------+ WSR-88D | 2.8 GHz | 0.63 MHz | 40 | 32 GW | 0.01 LY | Weather Radar| | | | | | -------------+--------------+-----------+--------+--------+-----------+ Arecibo | 2.380 GHz | 0.1 Hz | 40 | 22 TW | 720 LY | S-Band (CW) | | | | | | -------------+--------------+-----------+--------+--------+-----------+ Arecibo | 2.380 GHz | 0.1 Hz | 40 | 1 TW | 150 LY | S-Band (CW) | | | | | | -------------+--------------+-----------+--------+--------+-----------+ Arecibo | 2.380 GHz | 0.1 Hz | 40 | 1 GW | 5 LY | S-Band (CW) | | | | | | -------------+--------------+-----------+--------+--------+-----------+ Pioneer 10 | 2.295 GHz | 1.0 Hz | 40 | 1.6 kW | 120 AU | Carrier | | | | | | -------------+--------------+-----------+--------+--------+-----------+ It should be apparent then from these results that the detection of AM radio, FM radio, or TV pictures much beyond the orbit of Pluto will be extremely difficult even for an Arecibo-like 305 meter diameter radio telescope! Even a 3000 meter diameter radio telescope could not detect the "I Love Lucy" TV show (re-runs) at a distance of 0.01 Light-Years! It is only the narrowband high intensity emissions from Earth (narrowband radar generally) that will be detectable at significant ranges (greater than 1 LY). Perhaps they'll show up very much like the narrowband, short duration, and non-repeating, signals observed by our SETI telescopes. Perhaps we should document all these "non-repeating" detections very carefully to see if any long term spatial detection patterns show up. Another question to consider is what an Amateur SETI radio telescope might achieve in terms of detection ranges using narrowband FFT processing. Detection ranges (LY) are given in Table 2 assuming a 12 ft (3.7 m) dish antenna operating at 1.42 GHz, for various FFT binwidths (Br), Tsys, snr, time bandwidth products (twp = Br*t), and EIRP values. It appears from the table that effective amateur SETI explorations can be conducted out beyond approximately 30 light years provided the processing bandwidth is near the minimum (approximately 0.1 Hz), the system temperature is minimal (20 to 50 Degrees Kelvin), and the EIRP of the source (transmitter) is greater than approximately 25 terawatts. Table 2 Detection ranges (LY) for a 12 foot diameter amateur radio telescope SETI system, operating at 1.420 GHz. +-------------------------------+ | EIRP | | 100TW | 25TW | 1TW | 100GW | -------+-------+----------+------+-------+--------+------+-------+ Br | Br*t | Tsys | snr | Detection Range | (Hz) | | (kelvin) | | (LY) | -------+-------+----------+------+-------+--------+------+-------+ 0.1 | 2 | 50 | 25 | 28 | 17 | 3.4 | 1.1 | -------+-------+----------+------+-------+--------+------+-------+ 0.1 | 1 | 50 | 25 | 20 | 12 | 2.4 | 0.76 | -------+-------+----------+------+-------+--------+------+-------+ 0.5 | 2 | 50 | 25 | 12.7 | 6.4 | 1.3 | 0.4 | -------+-------+----------+------+-------+--------+------+-------+ 0.5 | 1 | 50 | 25 | 9 | 4.5 | 0.9 | 0.3 | -------+-------+----------+------+-------+--------+------+-------+ 0.1 | 20 | 50 | 25 | 90 | 54 | 11 | 3.4 | -------+-------+----------+------+-------+--------+------+-------+ 1.0 | 200 | 50 | 25 | 90 | 54 | 11 | 3.4 | -------+-------+----------+------+-------+--------+------+-------+ REFERENCES: Radio Astronomy, John D. Kraus, 2nd edition, Cygnus-Quasar Books, 1986, P.O. Box 85, Powell, Ohio, 43065. Radio Astronomy, J. L. Steinberg, J. Lequeux, McGraw-Hill Electronic Science Series, McGraw-Hill Book Company, Inc, 1963. Project Cyclops, ISBN 0-9650707-0-0, Reprinted 1996, by the SETI League and SETI Institute. Extraterrestrial Civilizations, Problems of Interstellar Communication, S. A. Kaplan, editor, 1971, NASA TT F-631 (TT 70-50081), page 88. (this section taken from sci.asto FAQ, see 5.1 for the copyright statment of sci.astro FAQ) Also see section 1.6 index 1 1.2 1.2.3 1.2.4 The quest for EXTRATERRESTRIAL INTELLIGENCE By Carl Sagan Cosmic Search Magazine Vol. 1 No. 2 May, 1978 Through all of our history we have pondered the stars and mused whether mankind is unique or if, somewhere else out there in the dark of night sky, there are other beings who contemplate and wonder as we do - fellow thinkers in the cosmos. Such beings might view themselves and the universe differently. Somewhere else there might exist exotic biologies, technologies and societies. What a splendid perspective contact with a profoundly different civilization might provide! In a cosmic setting vast and old beyond ordinary human understanding we are a little lonely, and we ponder the ultimate significance, if any, of our tiny but exquisite blue planet, the Earth. The Search for Extra-Terrestrial Intelligence (SETI) is the search for a generally acceptable cosmic context for the human species. In the deepest sense the search for extraterrestrial intelligence is a search for ourselves. ~ ~ ~ ~ ~ There are some who look on our global problems here on Earth - at our vast national antagonisms, our nuclear arsenals, our growing populations, the disparity between the poor and the affluent, shortages of food and resources, and our inadvertent alterations of the natural environment of our planet - and conclude that we live in a system which has suddenly become unstable, a system which is destined soon to collapse. There are others who believe that our problems are soluble, that humanity is still in its childhood, that one day soon we will grow up. The existence of a single message from space will show that it is possible to live through technological adolescence: the civilization transmitting the message, after all, has survived. Such knowledge, it seems to me, might be worth a great price. ~ ~ ~ ~ ~ There will surely be differences among civilizations which cannot be glimpsed until information is available about the evolution of many civilizations. Because of our isolation from the rest of the cosmos, we have information on the evolution of only one civilization - our own. And the most important aspect of that information, the future, remains closed to us. Perhaps it is not likely, but it is certainly possible that the future of human civilization depends on the receipt and decoding of interstellar messages...It is difficult to think of another enterprise within our capability and at relatively modest cost which holds as much promise for the future of humanity. index 1 1.2 1.2.4 1.2.5 Setup of the SETI@home project This was taken from a.s.s, and written by Eric J. Korpela, responding to a post by <demetrio@iquest.net> The Ultra 450 (4 cpu) is the science database server which stores results, does analysis, and also runs a splitter process. One Ultra 10 is the user database server which stores user information. One Ultra 10 workstation is the server machine which handles connections and directs them to the appropriate database This machine also has storage for the workunits themselves. One Ultra 10 is a full time splitter. Two Ultra 10s (one fast and one slow) are development workstations and an after hours splitters. One slow Ultra 10 is the web server and Dan's workstation. (Dan Werthimer) One Sparcstation 10 used to be a splitter (that's the old really slow one) and is used as a development workstation. index 1 1.2 1.2.5 1.2.6 What is a Gaussian? A gaussian is a mathematical function, mostly commonly describing the sort of distribution of values you get around the nominal value of some property or measurement as a result of measurement (and production errors). I would expect the maximum speeds of CPU chips to show this sort of pattern. It is often described as a bell curve, as it starts off rising slowly, then accelerates before starting to level off and come down in a mirror image of its rise, something like the cross section of a church bell. index 1 1.2 1.2.6 1.2.7 Analysis of the end data from the SETI@home project First thing, they'll be run through some RFI (Radio Frequency Interference for the newbies out there) rejection routines. There are a few different algorithms used. If a signal at the same frequency, but from a different place on the sky comes in within a few minutes, it's likely to be RFI. There are certain frequencies where continuous RFI is received, that will also be rejected. If a signal comes in at a chirp rate of zero, it's also likely to be RFI (extraterrestial signals should show a chirp signature due to the rotation of the earth and/or the rotaion of the ET's planet.) RFI rejection will probably eliminate the vast majority of the candidates (>99.99%). From there, the probablility that the candidate signals are just a random peak in the noise in the reciever, will be calculated. Then there'll be created a priority list of candidates based upon this probability, the signal strength, frequency width, goodness of gaussian fit, etc and pointed observations of the best candidates will be proposed. Somewhere in this chain, there'll also be looked for repeaters. Signals that show up at the same place in the sky at about the same frequency, but widely separated in time. Repeaters will likely get bumped to the top of the priority list. Another thing that will be looked for is signals with decent gaussian fits that show up at different frequencies, but at the same time. That might boost a candidates' priority as well. index 1 1.2 1.2.7 1.2.8 What are pulses and triplets? In the contexts of http://setiathome.berkeley.edu/, they are spikes that are repeated many times. Triplet means that there are three evenly spaced spikes. The triplet detection takes very little time to do, but it can only detect strong signals. The pulse finding algorithm can find very weak pulses, the more pulses the better the algorithm can find them. The pulse seeking, however, takes alot more time to do. index 1 1.2 1.2.8 1.3 The history and customs of alt.sci.seti and sci.astro 1.3.1 Charter for alt.sci.seti The original documents can be found here: The first post: http://x31.deja.com/[ST_rn=ap]/getdoc.xp?AN=484562021&CONTEXT=938880213.74252397&hitnum=3 938880213.74252397&hitnum=3 The control message, that created the group: http://x31.deja.com/[ST_rn=ap]/getdoc.xp?AN=484419771&CONTEXT=938880213.74252397&hitnum=2 938880213.74252397&hitnum=2 This was posted as the first post ever in alt.sci.seti on June 1st by Chris: Welcome to "alt.sci.seti" This group will probably be a little barren at first until it begins to propagate more thoroughly Why not post a message and get things rolling? Hopefully someone will one day create a FAQ for this newsgroup, but until then here's the charter... Charter: Discussion about the SETI (Search for Extra Terrestrial Intelligence) project and the search for extra terrestrial life in general. Also, discussion of the "http://setiathome.berkeley.edu/" project which allows individuals to utilize their computer's idle time to assist SETI in processing its overwhelming amount of recorded data. Should discussion about the http://setiathome.berkeley.edu/ project and the SETI project in general begin to crowd eachother, a second newsgroup devoted solely to SETI@home will be created with the name "alt.sci.seti.at-home" leaving "alt.sci.seti" for discussion of the SETI project. Binaries are not permitted and should instead be posted to the appropriate binary newsgroup or FTP site where they may be accessed. Justification: The SETI project has been going on for some years now and has amassed a great deal of interest. A quick search on DejaNews will show that there are thousands of posts regarding SETI, yet there is no currently available newsgroup to keep these discussions from getting lost in numerous other non-specific forums. "alt.sci.seti" will address this lacking. It will also provide a place for the enormous and growing number of people who have begun to participate in the http://setiathome.berkeley.edu/ project to discuss problems and solutions in assisting SETI to process all of its raw data. While the SETI@home project is expected to end around 2001 or so, it is likely that SETI will seek to call upon the public again in a similar way. This newsgroup will therefore continue to be timely and useful. This newsgroup was proposed, discussed, and approved in "alt.config" at the end of May 99. Created 01 Jun 99 index 1 1.3 1.3.1 1.3.2 Charter for sci.astro.seti RATIONALE: sci.astro.seti The Search for Extraterrestrial Intelligence (SETI) is the scientific discipline of searching for electromagnetic evidence of extraterrestrial civilizations. SETI has received a lot of attention recently due to the http://setiathome.berkeley.edu/ project. The SETI@home project has shown that at least several hundred thousand individuals are willing to dedicate computer resources to the search for alien radio signals. This has brought an increase in the amount of discussion of SETI and the possibilities of extra-terrestrial intelligence (ETI). Which has increased the number of posts about SETI in related newsgroups (sci.astro, etc.) by a large amount. The http://setiathome.berkeley.edu/ project is a distributed computing project which harnesses the computing power of hundreds of thousands of Internet connected computers to search for radio evidence of extraterrestrial civilizations. It is the newest and most public SETI project to date. Currently it has attracted almost a million people willing to donate computer time to this search. However, SETI@home is not the only SETI project, nor will it be the last new one. Several SETI projects are on the drawing board (1HT, etc.) and many of them will require as much or more computing power as the SETI@home project uses currently. It would be surprising if none of these new SETI programs use the distributed computing model that has allowed SETI@home to harness computing power equivalent to multi-million dollar super-computers for very low costs. This newsgroup will serve as a forum for discussion of SETI in general, and any SETI projects in specific. This includes discussion of http://setiathome.berkeley.edu/, both it's scientific aspects, as well as the use, configuration, and troubleshooting of the SETI@home client software and any similar software by future SETI projects. Additionally, it will serve as a place to discuss the technical specifics of all current and future SETI projects, and as a place for teachers who are developing curricula around SETI projects (such as SETI@home). CHARTER: sci.astro.seti This group will be unmoderated and distributed worldwide. This newsgroup is intended for the discussion of the Search for Extra-Terrestrial Intelligence. Appropriate topics for discussion include the following: 1) Discussion of SETI projects (such as SERENDIP, Phoenix, http://setiathome.berkeley.edu/, BETA, ARGUS, etc.) 2) Installation and configuration of the SETI@home client or other SETI projects using distributed computing. 3) Trouble shooting the use of the SETI client programs. 4) The possibilities of Alien life (Drake equation, planetary abundance and its relavance to SETI, etc.) 5) Discussion of statistical results for SETI projects. 6) The potential content of alien messages and how to decode them, as well as any messages we (humans) have / will / could send into space that are intended for ETI's (such as the Voyager record, the Arecibo message to M13, the Encounter 2001 project, etc.) 7) Potential alien technology in the context of detection / communication by / with humans (using visible light lasers instead of radio, for example). 8) Discussion of school curricula built around a SETI program Inappropriate posts include: 1) Commercial advertisements of any kind, including those for items related to SETI or any SETI project. 2) Binaries, with the exception of cryptographic signatures. 3) Discussions concerning UFOs, "alien abductions", etc, which should take place in other groups. index 1 1.3 1.3.2 1.3.3 Naming convention When talking about your computer(s) on the newsgroups, the following information is the minimum for other people to be able to determine if the machine is working optimally. CPU-TYPE, for example Pentium MMX, AMD Athlon, Pentium III.... CPU-SPEED, 133Mhz, 600Mhz.... Memory size Memory type FSB-speed (Front side bus speed) Also useful to include: Motherboard chipset Operating System index 1 1.3 1.3.3 1.3.4 .sig convention When reading the SETI newsgroups, you will find, that many use a * or # in their signatures. This strange way of bragging was first seen when the first people in alt.sci.seti started getting close and passing 100 Workunits done. They wanted to give themselves something for their effort, so they started giving themselves medals, putting them in their sig. Initially there was only one character used, the star (*) which you 'earned' for every 100 WU's. As time passed by, people started using more and more complex notations, which evolved into the complex system we have today. The newest .sig convention is as follows: The following notation is a way of expressing your personal or a group's contribution to the S@H program. PRECISION NOTE: These formats imply a certain range. 2.3* would for instance mean the interval of 230-239, whereas 2* would mean 200-299. The same goes for the symbolic notation. For instance ** would mean the interval of 200-299. More decimals added will imply greater accuracy for FORMAT 1 and more characters added would do the same for FORMAT 2. FORMAT 1: d.ds@d.ds Where "d" is a digit and "s" one or a combination of the following symbols: !=10 *=100 #=1000 !#=10000 (ten thousand) *#=100000 (hundred thousand) ##=1000000 (thousand thousand) etc... Notes: This table can be used for workunits and cpu-time alike. "@" only as a separator. Examples: 9@9.8! (9wu/98hr) 1.0!@2.5* (10wu/250hr) 2.1#@3.4!# (2100wu/34000hr) 3.0*#@3.6## (300000wu/3600000hr) FORMAT 2 - a more symbolic notation: Where the notation is composed of only symbols: !=10 +=50 *=100 #=1000 Notes: This table can be used for workunits and cpu-time alike. "@" only as a separator. Example: ****+@### (450wu/3000hr). All symbols are counted for their value and finally added up. Here 100+100+100+100+50=450wu in 1000+1000+1000=3000hr. It is preferred to sort the symbols. The greater first, then the smaller. FORMAT 3 - only work units: Format 1 or 2 where the cpu-time portion has been omitted. Example: 2.1# (2100wu), ****+ (450wu). FORMAT 4 - the most simple and understandable: (60WU/660hrs) DERIVED FORMATS - not preferred but no less understandable: Mixed schemes may occur. E.g.: 4*+@3# (450wu/3000hr). Today, there's even a program that will automatically make and update the signature for you! The program is available for Windows at http://www.geocities.com/theTFZ/SETI/SETIsig.html (requires VB6 runtime libraries) In addition many people have begun marking their posts with a short statement, indicating their opposition towards Olli (1.3.6) It usually goes something like this: +++++++ ONLY USE OFFICIAL SETI@HOME SOFTWARE +++++++ +++++++ DO NOT USE SETI@HOME PATCHES +++++++ It's inserted just before or in the .sig index 1 1.3 1.3.4 1.3.5 Labeling posts As there are many discussions about things not so relevant to SETI in these newsgroups (a.s.s. and s.a.s.), there have been developed many schemes, on how to label the posts. I suggest labeling posts in this newsgroup as follows: [sci] About science in general with no content about http://setiathome.berkeley.edu/ [meta] Discussions about discussing things [comp] Discussions about computing with no content about S@H [ot] Off-Topic: has nothing to do with SETI in any way. [patch] Discussions about patching the SETI@home client program. [brag] General bragging about your computer's speed, etc. [join] Invitations to join groups. [FAQ] Postings of Frequently Asked Questions or comments. (no label) Discussions about the SETI@home project, client, etc. Insert the [*] after any "Re:". Some newsreaders use the "Re:" to display which posts are replies. Please leave a space after the ":" in "Re: ". Not doing so confuses some newsreaders. Don't make up new tags. Make the tag general and the text after the tag specific. If you think that a new tag is needed, start a discussion about it under [meta] (NOT under the proposed tag!). If someone doesn't follow the rules. don't criticize. This is 100% optional. Posters are free to do as they choose. Limit your efforts to gentle persuasion only. The single most effective thing that you can do to promote this idea is to change the subject line and write a new one before the old one, so that the subject will be like this: Subject: <new subject> Was:<Old subject>. OFF topic: 1. BINARIES - a big NO. 2. ANY commercial advertising. 3. Number of WU's done. Use your .sig file to brag. 4. Personal Chit-chat use [ot]. 5. Posts about how old you are, what you do, etc. use [ot]. 6. How fast your CPU is as compared to others. [brag] index 1 1.3 1.3.5 1.3.6 Patching or cracking SETI@home Olli: When you hear a reference to Olli in the group, this is a reference to a German who thought, that he could just do as he wanted with the S@H program. What he did, essentially, was to decompile the code of the program, and release a new version of the program, unauthorized. This led to a big discussion in the alt.sci.seti NG, where he was eventually boo'ed out, because of his actions. Microsoft cracking the code: Microsoft wrote their own version of SETI, highly optimized for certain Windows hardware. They wanted to turn in the fastest WU times, to prove how fast Windows is. The SETI people discovered MS's cheating, and told them they must run the original SETI software, and threatened to dissolve the MS team, and said they would refuse results from any WU processed on a non-official SETI client. SETI had obvious concerns, that their algorithms might be programmed incorrectly. http://setiathome.berkeley.edu/'s (Eric J. Korpela) response to a post concerning the programming variables of the patch: +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- From: korpela@islay.ssl.berkeley.edu (Eric J. Korpela) Newsgroups: alt.sci.seti Subject: Re: seti patch bashing or the truth is... Date: 28 Oct 1999 16:06:33 GMT Organization: Cal Berkeley-- Space Sciences Lab Lines: 147 Message-ID: <7v9sa9$ror$1@agate-ether.berkeley.edu> In article <7v7b3b$70l$1@nnrp1.deja.com>, ******* ******* <*********-deja.com> wrote: >In article <7v4phg$1vv$1@agate-ether.berkeley.edu>, > korpela@islay.ssl.berkeley.edu (Eric J. Korpela) wrote: ><snip> >> In other words, if I don't get the same results using a hammer >> on a screw that I do using a screwdriver then something is >> wrong with the screwdriver? >> >> Olli has provided a means by which anyone with a compiler can >> replace the FFT routine with one that produces random >> numbers. Your conclusion would be that if the random number >> generator gets different results than the FFT does, something >> is wrong with the FFT. ><snip> > >Excuse me, but I have to ask. Are you really a programmer? Well, that depends upon how you define "programmer." I'm actually a scientist. My profession requires me to be a capable optical engineer, electrical engineer, mechanical engineer, and programmer. Above all it requires me to be a proficient systems engineer. And one of the things Olli's patch is missing is any consideration of the system aspects. Let me tell you some of the system aspects. The bottlenecks in http://setiathome.berkeley.edu/ are currently (in order of size): 1. The speed of the user database machine. This limits the number of connections we are able to handle per second. Sun has decided to give use another two Enterprise machine with two CPUs each, so this bottleneck will be going away soon. It will probably be another month before these machines arrive. The effect of a faster client on this bottleneck would be a higher rate of rejected connections and a lower system efficiency. -1 for Olli. 2. The rate at which work units can be split. The arrival of the two Enterprize machines will allow two more splitters to be used, to this bottleneck will go away, too. The effect of a faster client on this is nothing. +0 for Olli. 3. The fraction of time the S@H recorder is operating at Arecibo. We have no control over this parameter. When very RFI sensitive experiments are carried out at Arecibo, the http://setiathome.berkeley.edu/ data recorder is shut off to prevent interference. For the first 10 months of the year(1999 ed.), this fraction was about 1/2. The effect of a faster client on this is nothing. +0 for Olli. 4. The speed of the data recorder at Arecibo. Again, there's nothing to be done here but add another recorder working at different frequecies. That may be done at some point. The effect of a faster client on this is nothing. +0 for Olli. 5. The speed of the http://setiathome.berkeley.edu/ client. Note that this appears BELOW the previous four. Because of this, improving it doesn't improve systems efficiency. Let's assume #1 and #2 are solved and that we release a client that does the work in 1/4 the time. What is the response of the system to this optimization? Because data isn't coming in any faster, any speed increase in the client just increases the number of times a work unit is processes. Increase the speed of the client by a factor of 4 and you've increased the processing redundancy by a factor of 4. So there's no net processing efficiency increase. You've still got to store all the incoming results, so you're actually reducing efficiency slightly. So this is actually a negative for Olli. -1 for Olli The obvious conclusion is that Olli's patch, while increasing the efficiency of a specific instance of the http://setiathome.berkeley.edu/ client decreases the system effi that. There is a way around number 5, that is to add more processing capability to the client. This is what we were planning to do in the next release before we were so rudely interrupted. >I have seen >several posts in these threads that appear to be from you >that suggest you don't understand some things that I have >always considered pretty basic. I understand a bit more than you appear to. >If you are a scientist in general and a computer scientist >in particular, then I would think your primary concern would >be in getting the best tools to resolve the research >question in hand. Sorry, you don't seem to understand science. Faster doesn't mean better. And trustworthy is far better than faster. (Did you notice Olli's message stating that he would add malicious code to an employer's system in case he was fired "for the wrong reason." I would guess he considers adding malicious code to an employer's system "the wrong reason.") In addition, a scientist doesn't add unnecessary variables to an experiment. A different FFT algorithm for every platform is an unnecessary variable. >If you are not competent to assess his optimizations, that is >merely an unfortunate technical gap that you can choose to >address. Pardon me if I take offense to your insults. I never said we weren't competent to assess his optimizations. We don't have the time to deal with the patches every yahoo with a debugger and a compiler throws our way. >I'm not suggesting you should give up control of your project. Look at the http://setiathome.berkeley.edu/ web page... I never had control of the project. >But neither is it the case that your enthusiasm is holy and >other people's enthusiasm is cursed. When his enthusiasm leads him to give everyone with a compiler control of the science code, I'd call that cursed. >1) Optimize your inner loops better. We're working on it. >2) Learn about code signing. I think you're misunderstanding code signing. Code signing is used as proof to the user of who created the code, not as a means of preventing the user from tampering with the code. Even Olli will tell you that even if the code checks it's signature before running, that check ends in one or more conditional jumps that are easily removed. The other option is encrypting the entire executable, but even then you need to provide in the executable a decryption routine and a key. If you give the hacker those, you've given him the equivalent of a decrypted executable. Actually you don't even need those as the code decrypts itself to memory where it is easily acessible. >3) Consider modularizing your client. No way. >The last suggestion is most complicated, but if implemented >properly, it would actually allow you and everyone else on the planet > to reprogram the clients as your needs or their desires >required without even distributing new versions. Eric -- Eric Korpela | An object at rest can never be korpela@ssl.berkeley.edu | stopped. http://sag-www.ssl.berkeley.edu/~korpela +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- And another post made by Matt Lebofsky of the S@H team, concerning the ethics of patching: +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- From: mattl@albert.ssl.berkeley Newsgroups: alt.sci.seti,sci.astro.seti Subject: Re: Found Olli's Patch ! Date: 13 Dec 1999 17:31:52 GMT Organization: Space Sciences Laboratory Lines: 61 Message-ID: <833ai8$pd1$1@agate.berkeley.edu> Despite all the reasons below being completely valid, I'll give you another one: http://setiathome.berkeley.edu/ doesn't allow unauthorized access to our data server. Patched clients which look like real clients that contact our server could, in theory, do any number of things that cause harm. In short, it's a form of hacking. Of course people believe the patch is safe and accurate. We here at http://setiathome.berkeley.edu/ don't know that, nor has the patch creator been willing to prove it. The author of this patch even goes as far as to completely *refuse* to identify his patch so our server can recognize it as a patched client. To me, this is an obvious affront. In short, we can't tell if results are from patched clients or not. The patch could easily be modified to fix this. It hasn't been. Case closed. Too bad I didn't know about Olli before I went touring in Germany for five weeks this past summer. Hopefully I'll be back again in fall of '00. If anybody knows where he lives/works/hides let me know. I'd like to discuss the patch in person. This is my first AND last message on the matter. - Matt - http://setiathome.berkeley.edu/ In article <8327ak$ln4$1@nnrp1.deja.com>, Daviddth <daviddth@my-deja.com> wrote: >In article <3853bf65.1671925@uutiset.nic.fi>, > j.k.@gotmail.com (Jan Knutar) wrote: > >>>Found Olli's Patch ! > >> DO NOT USE ILLEGAL PATCHES! > >Please tell us why not. In your answer, please do not include: > >Morality - Your morals may not be others > >Scientific results - The patch has proven itself accurate here >in multiple tests > >Scientific "purity" - if the patch is accurate, but quicker, > then what is the problem in using it. > >Dislike of Olli - There are plenty of people that do not like > others, but respect their work. Learn to live with this anger. > >I await your reply. > >-- >David >http://setiweb.org/ >http://www.lisp.com.au/~daviddth/king/ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- Please note that these Usenet posts that have been quoted here aren't meant to represent the absolute truth, they are meant to give you SETI@home's opinion on patching, and to give you some interesting reading. There's an excellent page, dedicated to this very subject here: http://home.hccnet.nl/a.alfred/p-free-p1pfp.html index 1 1.3 1.3.6 1.3.7 What is a 'vcard' and why do people tell me not to use them? A vcard is only readable by a newsreader capable of rendering html. For this reason and because vcards are 'attached' to the Usenet posting, they are not recommended. They are also very annoying in that they very rarely change. This is analogous to giving everyone you talk to your business card each and every time you talk with them... after a while, we have enough of your cards, and we really don't want any more. A signature is the preferred method to communicate pertinent personal information. Please see the section on 'signatures' or '.sig' for more information. index 1 1.3 1.3.7 1.3.8 What is PST and PDT? They're timezones ;) PST - Pacific Standard Time (GMT - 8) PDT - Pacific Daylight Time (GMT - 7) (GMT = Greenwich Mean Time) index 1 1.3 1.3.8 1.4 What will happen if an extraterrestrial signal is detected? A procedure has been agreed upon by SETI researchers around the world. First, other SETI researchers will independently verify the signal. If the signal is real and can't be explained by man-made sources (satellites, reflections, etc.) then press agencies and governments will be notified in a systematic way. index 1 1.4 1.5 How is data collected from the telescope and transmitted to other machines for analysis? Data is recorded on high density tapes at the Arecibo telescope in Puerto Rico, about one 35 Gbyte tape per day, then mailed to Berkeley, then divided into 0.25 Mbyte chunks which get sent from the http://setiathome.berkeley.edu/ server over the internet to people around the world to analyze. Arecibo does not have a high bandwidth internet connection, so data must go by snail mail to Berkeley at first. index 1 1.5 1.6 Are earth signals strong enough to be detected? What sort of spectrum is currently being emitted by earth? Is that signal visible say 10 or 50 light years away? If SETI were on a planet say 10-50 light years from here and running this project there, would it be able to detect earth's signal (assuming it was looking in our direction)? Earth is polluting space with radio and television signals that might be detected by nearby advanced civilizations, but it would be difficult for such a civilization to discover these signals if they only have Earth's current level of technology (eg: if they have an Arecibo like telescope and http://setiathome.berkeley.edu/ like search). Early TV shows like I Love Lucy and Ed Sullivan left the earth about 40 years ago, so have gone out 40 light years, reaching several thousand nearby stars. But these signals are relatively weak and http://setiathome.berkeley.edu/ is not likely to detect the equivalent of Earth type TV transmitters, even on the nearest stars. Earth's strongest transmitters might be somewhat easier to detect, such as those emitted by military radars, or some radio telescopes. The Arecibo telescope transmits very powerful signals when it is used as a radar system to study planets, asteroids and the ionosphere. These radar signals are powerful enough to be detected 10,000 light years away by searches like http://setiathome.berkeley.edu/, except for three big caveats: a) The Arecibo transmissions are in a very tight beam (they are not omnidirectional, like TV and military radar), so they only cover a very small part of the sky at once (about a millionth of the total sky). It's is unlikely another civilization will be within one of these narrow beams. b) The Arecibo transmitter's oldest signals left Earth about 30 years ago, so have only travelled 30 light years. c) http://setiathome.berkeley.edu/ is not searching the band of frequencies that the Arecibo transmitters utilize (although the older SERENDIP III program did survey one of those bands). Also see section 1.2.3 index 1 1.6 1.7 What if my computer finds a signal -- how will I know? You won't know, because your computer can't find a signal all by itself. All it can find is bits of pattern that are worth further investigation and correlation with other bits of pattern in other work units. These will be flagged for the http://setiathome.berkeley.edu/ staff to look into, and when they've verified it by various methods with scientific rigor, then they'll make the announcement. Don't worry -- they'll give you co-credit. index 1 1.7 1.8 How can I hear the signal? The long answer: the data isn't sound, it's radio waves. You can make up an arbitrary set of rules to "map" radio waves into sound, but since you picked the rules, you really decide what you're hearing, not the signal. As an analogy, imagine if you wanted to make a picture of the melody of a song was. You could decide (ala "Close Encounters") that a middle C turned into a teal light, and the G above middle C turned into a red light. Then any given melody becomes a set of colors. But when you're done, the flashing lights you see tell you more about the particular rules of mapping you made up, than they did about the melody you started with. The short answer: And even if you did, it'd just sound like white noise. So turn on some speakers without any signal hooked up to them, or tune your TV to a channel you don't get, and listen do that. It's about the same thing. The http://setiathome.berkeley.edu/ team has decoded one, and it's located her: http://setiathome.ssl.berkeley.edu/audio.html Nothing but white noise. Jan Knutar has made a program that maps the radio waves into sound atleast one way, the result sounds, not surprisingly, like noise. The program, which is available for both Linux and Windows PC's, is downloadable at http://gamma.nic.fi/~jknutar/wu2wav/ index 1 1.8 1.9 Is there something in it for me? No. Unless you count the chance to be the first one to make contact with "The little green men" index 1 1.9 1.10 Why doesn't SETI@home release the sources for the clients? The sourcecode is not released because of both security and scientifical reasons. If the code was available freely, anyone could replace the core analyzing algorithm with some superfast random number generator, for example. http://setiathome.berkeley.edu/ is a scientifical project, speed is not everything. In the newsgroups, it has been hinted that the source will be released when the project is over. There are actually small pieces of the sourcecode available. Some of the early clients were GPL'd, and you can find the sourcecode for them on the Internet. In a post to alt.sci.seti by Eric Heien, additional details of the code used was given. Parts of the post below: ----clip------------------------------------------------------- In the old versions, we used the four1 procedure for FFTs from Numerical Recipes in C. You can see the exact code and scientific and mathematical derivations for it in Numerical Recipes in C. It's available at http://www.nr.com/, or you can just jump directly to http://www.ulib.org/webRoot/Books/Numerical_Recipes/bookcpdf/c12-2.pdf for the specific section. The new FFT used in the beta versions (and soon version 3.0) is the Ooura FFT library. You can get the code and benchmarks at http://momonga.t.u-tokyo.ac.jp/~ooura/fft.html. The new pulse finding code is called the Fast Folding Algorithm (FFA). I'm sure there are several sources and papers for it on the Internet, but the first I saw was http://www.mpifr-bonn.mpg.de/staff/peter/ffades.en.html. This particular analysis routine was written by us, but was based on code that is publicly available (for example, from the above link). The triplet code is based on ideas developed by some NASA scientists (I don't know their names offhand). The code was actually entirely written here rather than based on other code, but I'm sure there are papers and sample code available somewhere out there for it. ----/clip------------------------------------------------------ See also SETI@home's official FAQ at http://setiathome.ssl.berkeley.edu/faq.html#q1.9 index 1 1.10 top index 2 Problems and questions concerning SETI@home 2.1 Speed improvements 2.1.1 What's the fastest computer to use for this project? The computer you have. If it can run http://setiathome.berkeley.edu/, running it will make more contribution than not running it. Even if you're only doing half as many work units per month as the guy sitting next to you, you're still doing more than you would if you weren't doing them at all. If you want to see, what the fastest computer possible is, check the following sections. index 2 2.1 2.1.1 2.1.2 Can I make it run any faster? 1. Make sure you've got it set up to run continuously (a machine with at least a 200 MHz clock is desirable; if an Intel Platform then at least a BX or JX chip set is even better, otherwise the performance of the system might be untolerable) 2. Each time http://setiathome.berkeley.edu/ launches, it optimizes itself for the current monitor color depth (256 colors, Thousands, Millions). If you change the color depth while SETI@home is running, it may slow things to a crawl. 3. It should run reasonably at any screen depth, but it will run somewhat faster at lower screen depths (256 colors) than higher ones. Screen resolution (800X600, 1024X732, etc.) should have negligible effect on speed. 4. Make sure the graphical display window is never showing (run the window collapsed on the task bar) 5. If running Windows 95/98/NT, make sure your screen saver is set up for "Blank Screen". For some reason when screen saver is set to "http://setiathome.berkeley.edu/" with "continuous run" enabled the client seems to waste time fighting with itself. It can turn out a work unit in half the time by doing this. 6. If running on WindowsNT 4 then try running the client at a higherpriority. To do this you must do the following: 4a. do a 3 finger salute (ctrl-alt-del) to bring up the "Windows NT Security" panel 4b. click the "task manager" tab 4c. locate the task called http://setiathome.berkeley.edu/ 4d. right click on it 4e. clink task priority (low is the default) 4f. select either "medium" or "high" (but not "real time" or you might need to reboot in order to regain control of your machine) On windows 9X, you can use the shareware program taskinfo. Start Taskinfo, right click http://setiathome.berkeley.edu/, change priority, realtime. Taskinfo can be found at http://www.iarsn.com/). Be warned, changing the priority to realtime is for the purists only. It will give nearly all CPU time to the S@H client, making your system unresponsive. 7. Use the text-client. Even though it's not as much fun as the graphical, it does run faster. It will run on any win98/NT system (NT calls have been ported to win98. The text client will also run on Windows 95 if you upgrade Winsock to version 2. You can find the upgrade at Microsoft's website (http://www.microsoft.com/). index 2 2.1 2.1.2 2.1.3 REMOVED March 2000, was: Can I run the SETI@home text-client on Win95? Now appears in section 2.21. index 2 2.1 2.1.3 2.1.4 Will SETI@home run faster with more RAM (e.g., 256 MB instead of 128 MB)? http://setiathome.berkeley.edu/ uses about 16 MB of RAM while it's running. Beyond a certain point (typically 64MB, more if you run memory-itensive applications) more RAM won't make it run faster. index 2 2.1 2.1.4 2.2 REMOVED April 2000, was: I'm using a proxy server, and I can't connect - what do I do? Was removed because the http://setiathome.berkeley.edu/ client's hugely improved proxy support. Consult 2.20 for help on the CL client. index 2 2.2 2.3 I had a work unit that got returned after only 5 minutes. What's wrong? The http://setiathome.berkeley.edu/ program found enough noise that it determined the packet was messed up with it. It's like if you're trying to hear an egg being dropped to the ground on the other end of a football field, and someone blares a megaphone in your ear. No point in continuing to listen for the egg. You wont get credit if it took under 10 minutes to complete the workunit. This is to eliminate results from the buggy mac clients that finished all workunits in no-time. There are a few examples of excessive noise in workunits at the SETI@home website: http://setiathome.ssl.berkeley.edu/rfi/index.html index 2 2.3 2.4 I heard I was getting the same work unit as everyone else. Is the program wasting my time? Nope, because the only time you're giving it is time your computer would have wasted anyway. Yes, early in the program there were times when the same work units went out over and over, due to overloading of the http://setiathome.berkeley.edu/ servers that were supposed to be making new ones to send out. (They didn't expect half a million people to sign up, and they don't have enough staff or computing power to keep up with it.) And since then, the same work units are still sent out to several people, for various reasons (for instance, more than half the people who signed up have never returned their work units, and probably dropped out) But new work units are being sent out too, so just leave your SETI@home program working and it'll take care of the details. Note: If workunits are sent out multiple times, they can be doublechecked by http://setiathome.berkeley.edu/. index 2 2.4 2.5 My computer wanted to upload to the SETI@home server but said it couldn't connect or reported error 10065. Are they still there? Yes But they're sometimes swamped with traffic. Just try again later. Error 10065 is a winsock error - means the same. The page http://setiathome.ssl.berkeley.edu/sstatus.html is auto-generated and tells you whether http://setiathome.berkeley.edu/'s data server is running or not. Sometimes the error might be between your ISP and Berkeley, sometimes at your ISP. Most operating systems have tools to help you determine where the error is. If you want to try to find out what's wrong when you can't connect, try using the 'traceroute' command (in Windows: tracert). You bring up a command prompt and type in the command followed by the site you wish to connect to, in this case shserver2.ssl.berkeley.edu (for the S@H server). If you get "Cannot resolve" or similar error, then your computer was unable to translate the address into an IP number. The cause of that could be that your ISP's DNS server is down or not working properly. index 2 2.5 2.6 What if someone fakes a result to make it seem like they found a signal? The http://setiathome.berkeley.edu/ staff will be reviewing the actual data that produced the result, and if they don't find the same results, they will discard the fake. Besides, while it's not impossible, it might be harder than you think to fake a result file. Since some workunits are sent out more than once, http://setiathome.berkeley.edu/ can detect errors by comparing the results. During the time of the project, the sky will be scanned several times. It's very unlikely that a cheater would get a workunit from the same location in the sky more than once. index 2 2.6 2.7 SETI@home keeps getting a 'Bad Header' error. What can I do? 1st Possibility First close the http://setiathome.berkeley.edu/ client. Open the work_unit.sah file in the SETI@home directory and delete all the lines that appear before the 'type=work unit' line, but do not delete this line. Save the work unit file then restart the SETI@home client. 2nd Possibility If you installed the client software from the FreeBSD ports collection, install the highest numbered version available from: http://setiathome.ssl.berkeley.edu/unix.html. If you then get an error with ld.so, go to /usr/src/lib/compat and make, make install compat22. 3rd Possibility There's a problem at Berkeley with the servers. Try again later. If you look closely at the GUI client while it returns, you might or not might see "all data sent". If that happens, then the results were sent back allright. If you did not see that, then you can try to use the following to get a new workunit. Close http://setiathome.berkeley.edu/. Make sure it is closed, right click the icon in the systray and exit the client. Go to the http://setiathome.berkeley.edu/ folder. Move the files "outfile.sah" and "result.sah" to a temporary folder. Start http://setiathome.berkeley.edu/. The client should get a new workunit. If this does not work and you get bad header again, then the problem is probably one of the other possibilities. When you wan't to try to send the results back again for the workunit that got the bad header error, then: Exit the client. Move the text files "work_unit.sah", "result_header.sah", "outfile.sah" and "state.sah" to another temporary folder. Move back the files from the first temporary folders. Start notepad, select save as, move to the http://setiathome.berkeley.edu/ folder (usually c:\program files\SETI@home), save the file as "stop_after_send.txt". Start SETI@home. The results should be sent now. Exit SETI@home and delete the files "result.sah", "outfile.sah" and "stop_after_send.txt". You can now move back the files you moved to the temporary folder. If you are unsure which files should be moved away, then move all the text files. index 2 2.7 2.8 Suddenly, without warning my system crashes - what should I do? Make sure you have the latest video (try first) and peripheral drivers for your system. This is often the cause of lockups and crashes, at least for Win9x. If your machine suddenly reboots itself or you get a blue screen, then it could be that the processor or some other part of your computer is overheating. Check that you have enough cooling for your processor. Most new computers have built in sensors for measuring the temperature of various parts in your computer. index 2 2.8 2.9 I can't see the new WUs I've processed in the status area. Have they been registered at SETI@home? Probably. Sometimes you first get Stats at next WU. You can also check with the personal stats available at the SETI@home website (http://setiathome.ssl.berkeley.edu/). Those stats are currently updated almost immediately so they should be the most accurate. index 2 2.9 2.10 I want to run the text-client as a service in NT - how do I do that? Method nr.1 You need to be administrator to do it. The easiest way is if you have IE4 or IE5 and Task Scheduler. It comes with IE5 and is an option in IE4. Set up a task to run when your PC boots to launch it. When you boot your PC, let it sit at the logon screen for 30 seconds or so to verify the Task Scheduler service has started and it has launched the task. Now it will run in the background and the only way to stop it is with kill.exe from the NT resource kit. If you don't have IE4/5, then use the Schedule Service built into NT, but you have to be an administrator to do this. Make sure it is set to run and log on as you. Then schedule it to run in about 2 minutes using the AT command. Type AT /? from a command prompt for help. You do NOT want to use the /interactive switch. It will then run in the background. This is easier to use if you have the Resource Kit as well because you could use the SOON.EXE command in a batch file in your startup group. *Note: You must run the seti client manually the first time to configure it. Afterwards you may allow it to start automatically. Method nr.2 provided by Peter Yackel: You need two files from the NT resource kit: srvany.exe and instsrv.exe. You'll use these files to install SETI as a service. Here's the procedure: Copy srvany.exe to the SETI@home directory. (I'll use c:\seti in this example. I also assume the seti executable to have been renamed to seti.exe) Copy instsrv.exe to the winnt directory. Click Start, Run, and type "cmd" to open a DOS window. Type: instsrv SETI c:\seti\srvany.exe Type "exit" to return to NT Click Start, Run, and type "regedit" Go to the following registry key: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services Expand it by clicking the + Highlight SETI, then right click and select New, Key Type: Parameters Highlight Parameters, right click and add the following New String Values Names: Application AppDirectory Now double-click the Application value name you just created and enter the following Value Data: c:\seti\seti.exe Do the same for AppDirectory but enter c:\seti for the Value Data. Exit the Registry Editor. Go to Control Panel and double-click Services. Go to SETI and double-click on it. Set the startup to Automatic. Click OK. This will cause the service to automatically start at the next boot. To start the service immediately, highlight Seti and click Start. *Note: You must run the seti client once manually to configure it. Afterwards you may allow it to start through services. Method nr. 3 Use a third party utility. (See 4.2.11) index 2 2.10 2.11 Can I run the client invisibly on Win95/98? Nr 1. This has been found to work in the past but has failed with some Client/OS configurations. Before you do this, please bear in mind that you have to have permission to run http://setiathome.berkeley.edu/ on the computer. Do not use this method to run SETI@home on other's computers. It is a violation of the license agreement to run SETI@home on computers you do not have permission to run SETI@home on. Install and setup the client in the normal way. After you have completed the setup of the client making sure that it is running all of the time and not just in screen saver mode. Run regedit and search for http://setiathome.berkeley.edu/ It will probably be in there more than once, so the one you are looking for looks like this: seticlient C:\Program Files\SETI@home\SETI@home.exe -min This string value will be in the key Run. Move it to the RunServices Key and remove it from the Run key Restart and the next time it comes up it will run even before you log in with no icon visible. Nr 2. This method works well with the Command Line version and Win 98. SetiLog is a third party utility that creates and maintains a file of completed work units. It can be used in conjunction with SetiWatch to monitor the progress of the client. Use SetiLog to start the client using the command line switch /H This will start the client hidden. Once the client starts and runs with this method create a shortcut to SetiLog in the Start Up folder. The client should now start on boot and run invisibly. In order to shut down the client you will have to ctrl-alt-del and select SetiLog. You can also create a registry entry to start the client automatically. I had to use the Shortcut to start SetiLog instead of the path directly to SetiLog. The registry entry should go in HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run and can be named anything, but should contain the value of the path to the Shortcut to SetiLog, not the path to SetiLog. Other third party utilities may also have options to start the clients invisibly. index 2 2.11 2.12 Sometimes the size of the workunit.txt file differs in size. Sometimes it's 340, sometimes 341, and yet other times 351. Is there something wrong? The difference between 340k and 341k is most likely a difference in the number of telescope position strings reported in the header. The 351k is an benign bug in the portion of the splitter which determines where the work unit ends. It basically tags on an extra 10.67k (IIRC) of data, that the http://setiathome.berkeley.edu/ client ignores. It has to do with the timing relationship between position information from the telescope and the start of a block on the tape. All of the data in the work unit is still OK. index 2 2.12 2.13 I don't have a permanent Internet connection, and have to pay for all my phone calls and net usage. Can I run SETI@home without going bankrupt? http://setiathome.berkeley.edu/ will only connect to the Internet when you want it to. The GUI (slow, pretty graphics) clients have an option under "Preferences" to "Ask me before connecting to the Internet", and the CL (fast, no graphics) clients have a switch "-stop_after_process". In each case, this will prevent an internet connection being made until you're ready, and means the clients can be left safely unattended. When you are ready to connect to the Internet (say, for a normal browsing, usenet or mail session) you can make the client send results and retrieve a new Work Unit. In the GUI case, it will ask you to make a connection. For the CL client, stop the process, then restart it without the "-stop" switch, and it will connect automatically. Depending on the load at the Berkeley servers, within 5 minutes you will have sent your results and received new work to do. Programs have been developed, that will buffer the WU's for you, see sections 3 and 4. If you are still concerned that the clients will connect when you don't expect, make sure your system is configured *not* to connect "on demand" without prompting you for confirmation (a good idea anyway if you are concerned about unwanted connections), switch off your (external) modem, or pull the telephone plug from the socket (internal modem). index 2 2.13 2.14 I already run the distributed.net RC5-64 client. Can I run SETI@home as well, or do I have to choose which project to support? Both clients can run simultaneously. In screen-saver mode the http://setiathome.berkeley.edu/ client seems to take priority. For those that don't allow the clients to connect automatically, the advantage is that the RC5-64 client can download multiple blocks to work on as opposed to SETI@home's single work unit. This means that while the SETI@home client waits for you to connect next, the RC5-64 client can continue working on its own tasks. index 2 2.14 2.15 What happened to the gaussian information display in the new Mac and Windows clients? The client is finding gaussians with lower fits, do the 2.x clients find more aliens or something? The 2.x GUI clients introduced new gaussian curve fitting graphics. To not make the new display blank all the time, http://setiathome.berkeley.edu/ decided that the client should show all gaussians found, no matter how weak they were. The gaussian power is lower than in 1.x, too low to be reported back to SETI@home. The 3.x clients alternate between gaussians, pulses and triplets. index 2 2.15 2.16 Can I run SETI@home 24/7 if I don't have a permanent Internet connection? There are a couple of ways of running multiple instances of http://setiathome.berkeley.edu/ such that, if one instance finishes its Work Unit, another will take over, so making sure that your system is working flat out most of the time. Under Windows 98/NT/2000 Command Line (non-graphic), and various *ix flavours, multiple clients in different directories may be "chained" to run consecutively by specifying the "-stop_after_process" switch for each. When one Work Unit is finished, that client will stop and another will take over. When all clients are done, an Internet connection can be made to send all results and receive new Work Units. The process may then be repeated. Also, there's the possibility of using one of the WU caching add-ons, such as SETIBuf or SETI Manager for Windows, SETI Unit Manager for Mac, or Hiram Clawson's RunCache & FetchCache for Unix like systems (for example Linux). See section 3 and 4. Running several clients simultaneously on a single-processor machine, or running more clients simultanesouly than the number of CPU's in your machine is not recomended, running them after eachother will give you better performance. index