Nebula: Completing the SETI@home pipeline

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Profile Raistmer
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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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