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Nebula: Completing the SETI@home pipeline
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Filipe Send message Joined: 12 Aug 00 Posts: 181 Credit: 8,601,361 RAC: 1,453 ![]() ![]() |
From what I read Nebula is going to run on a UNIX cluster, not on a variety of HW/SW architectures like the front-end SETI@home. We are talking about back end for Seti@home Part II (Seti@home 10) |
Jim1348 Send message Joined: 13 Dec 01 Posts: 198 Credit: 354,999 RAC: 120 ![]() |
EDIT- and as we've seen lately, Seti is having trouble supporting the current load. How well would it cope with twice the number of users or 5-10 times the WUs being crunched per hour? I was surprised when I got the recent email asking for help, since I thought they were at the limit too. But if they could get the 5-10 times improvement in GPU processing (I have no idea how), that could help reduce the server load if they made the work units larger, I would think, depending on where the bottleneck is. |
![]() Volunteer moderator Project administrator Project developer Send message Joined: 13 Feb 99 Posts: 101 Credit: 443,860 RAC: 568 |
Yup. Thanks for noticing this. |
![]() Volunteer tester ![]() Send message Joined: 5 Jul 99 Posts: 3827 Credit: 22,087,962 RAC: 14,265 ![]() |
Read about Nebula, a new and faster back end for SETI@home. Nebula removes RFI and finds persistent signals. Its goal is to let us finish the current SETI@home experiment. David, thank you for this info, it is much appreciated, Best Wishes, Byron. |
![]() ![]() Send message Joined: 29 Jun 99 Posts: 7360 Credit: 17,770,549 RAC: 13,319 ![]() ![]() |
Read about Nebula, a new and faster back end for SETI@home. Nebula removes RFI and finds persistent signals. Its goal is to let us finish the current SETI@home experiment. A major breakthrough fo the project. +1 |
![]() Volunteer tester ![]() Send message Joined: 5 Jul 99 Posts: 3827 Credit: 22,087,962 RAC: 14,265 ![]() |
Hi betreger, thank you.Read about Nebula, a new and faster back end for SETI@home. Nebula removes RFI and finds persistent signals. Its goal is to let us finish the current SETI@home experiment. ~~~~~~~~~~~~~~~~~~~ Hi David, and thank you, the following I read some where, but it is my favorite thought :-) While a successful SETI Signal, may be a long time in coming or, we could Receive the next WOW Signal in the next 5 Minuets, or even if it takes Generations of Humans, SETI@home is still worth while, The knowledge gained from any failure only contributes to successes, in science in the future. The human condition motivates us humans, to learn about everything and continue despite the overwhelming, odds until we humans finally succeed. Many of the things, we take for granted today , are the direct result of this human behavior, Things like computers, light bulbs, telephones, airplanes, and rockets and spacecraft ..... to furthest edge of our solar system, are among them. The only requirement is that we try. The probability of success is difficult to estimate but if we never try, the chance of success is , zero Best Wishes, and thank you David, Byron, |
![]() Volunteer developer Volunteer tester ![]() Send message Joined: 16 Jun 01 Posts: 5927 Credit: 80,621,497 RAC: 30,987 ![]() ![]() |
To estimate the false positive rate, we could inject synthetic ET signals of various types and powers, run them through the back end, and see which of them are rejected as RFI, and also which are detected by the scoring algorithm. We haven't done this yet, but we should. Very true statement. I found projected 1% of false positives little frightening (or no so little). 1 chance of 100 that we throw away hard-earned ET signal just with other RFI - doesn't sound like acceptable to me. On frontend software we struggle to get 99,9+% of correctness in calculations and avoidness both false positives and false negatives in found signals reporting. So, to have 1% chance to "throw baby away with the water" on last processing stages seems not very right. False positive rate for RFI removal should be lower IMHO (or variable in few separate rounds of final processing). SETI apps news We're not gonna fight them. We're gonna transcend them. |
![]() Volunteer developer Volunteer tester ![]() Send message Joined: 16 Jun 01 Posts: 5927 Credit: 80,621,497 RAC: 30,987 ![]() ![]() |
Regarding Zone RFI. This is called zone RFI because it occurs in particular frequency zones. Our challenge is to identify these zones. We do this by looking for frequency ranges that repeatedly have more than their share of signals. Let suppose smth like Efremov's Great Circle exists, some global interstellar communication network. Just as we have on Earth let suppose particular frequency bands reserved for that global network. All civilizations that discover network use same frequency band for communications. Also, suppose our detection algorithm catches some of those messages as let say Spikes. So, we will have increase in Spikes number on interstellar communication freq band. The question is: what in current Zone RFI implementation allows to distinguish such situation from terrestrial RFI and keep those signals w/o marking them ALL as zone RFI and cutting us from interstellar communication network? SETI apps news We're not gonna fight them. We're gonna transcend them. |
![]() Volunteer developer Volunteer tester ![]() Send message Joined: 16 Jun 01 Posts: 5927 Credit: 80,621,497 RAC: 30,987 ![]() ![]() |
So we remove signals with longer FFT lengths (i.e. precise frequency measurement) and very low chirp rates. Hm, this part sounds like much easier to do on front end processing stage. Just skip chirp<A and FFTlength>N processing at all. Currently we start with zero chirp and that requires separate treatment of first few iterations by TwinChirp approach - +0 is the same as -0 so no "twin" actually. SETI apps news We're not gonna fight them. We're gonna transcend them. |
![]() Volunteer developer Volunteer tester ![]() Send message Joined: 16 Jun 01 Posts: 5927 Credit: 80,621,497 RAC: 30,987 ![]() ![]() |
Thanks again for well-structured and thorough overview of back-end stages of MultiBeam client results. Also, would be very interesting to read similar document about the destiny of AstroPulse client data. What plans for its backend processing? Will they merged into Nebula structure as new type of signals? Or maybe any plans for creating similar but separate structure? Could you or some other team member do such overview for AstroPulse, please? SETI apps news We're not gonna fight them. We're gonna transcend them. |
SALLY P. NEW Send message Joined: 18 Jul 06 Posts: 1 Credit: 100,403 RAC: 0 ![]() |
I pretty much don't know what you are all talking about. I just use my computer to process the pieces that are sent to it. I am now able to throw 2 more computers into the fray. So I want to know a couple of things. 1. Do I need to download new programming in order to process the information with Nebula? 2. Is SETI going away? I am confused by some of the posts. Obviously I am not a computer wiz nor am I an astrophysicist. I am just a retired nurse trying to contribute as I am able. HELP Thank you Sally New |
![]() Volunteer developer Volunteer tester ![]() Send message Joined: 16 Jun 01 Posts: 5927 Credit: 80,621,497 RAC: 30,987 ![]() ![]() |
You don't need to download anything new. These Nebula forums just describe what additional processing (postprocessing) is done with data your and others PC returned to servers. SETI apps news We're not gonna fight them. We're gonna transcend them. |
Jim Plummer Volunteer tester Send message Joined: 15 May 99 Posts: 4 Credit: 2,990,812 RAC: 0 ![]() |
Well said!! |
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SETI@home and Astropulse are funded by grants from the National Science Foundation, NASA, and donations from SETI@home volunteers. AstroPulse is funded in part by the NSF through grant AST-0307956.