Nebula: Completing the SETI@home pipeline

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Filipe

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Message 1831875 - Posted: 22 Nov 2016, 8:48:42 UTC

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.
Tullio


We are talking about back end for Seti@home Part II (Seti@home 10)
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Message 1831908 - Posted: 22 Nov 2016, 14:13:09 UTC - in response to Message 1831786.  

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.
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Message 1833209 - Posted: 29 Nov 2016, 21:30:54 UTC - in response to Message 1830654.  

Yup. Thanks for noticing this.
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Message 1833417 - Posted: 1 Dec 2016, 2:19:28 UTC - in response to Message 1829052.  

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.
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Message 1833419 - Posted: 1 Dec 2016, 2:25:24 UTC - in response to Message 1833417.  
Last modified: 1 Dec 2016, 2:26:36 UTC

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.

A major breakthrough fo the project.
+1
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Message 1833500 - Posted: 1 Dec 2016, 17:44:13 UTC - in response to Message 1833419.  
Last modified: 1 Dec 2016, 18:37:14 UTC

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,
thank you for this info, it is much appreciated,
Best Wishes,
Byron.

A major breakthrough fo the project.
+1
Hi betreger, thank you.


~~~~~~~~~~~~~~~~~~~

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,
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Message 1833814 - Posted: 3 Dec 2016, 9:02:06 UTC
Last modified: 3 Dec 2016, 9:04:33 UTC

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).
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Message 1833823 - Posted: 3 Dec 2016, 9:31:54 UTC

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?
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Message 1833826 - Posted: 3 Dec 2016, 10:12:48 UTC

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.
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Message 1833842 - Posted: 3 Dec 2016, 12:21:55 UTC - in response to Message 1829052.  
Last modified: 3 Dec 2016, 12:23:43 UTC

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?
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Message 1834229 - Posted: 5 Dec 2016, 6:27:42 UTC

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
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Message 1834232 - Posted: 5 Dec 2016, 6:37:51 UTC - in response to Message 1834229.  

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.
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Message 1834396 - Posted: 6 Dec 2016, 0:18:06 UTC - in response to Message 1830195.  

Well said!!
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Message boards : News : Nebula: Completing the SETI@home pipeline


 
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