The Outsider's Inside View post#006 - Rock and Roll


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Profile KevinDouglasPhD
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Message 523765 - Posted: 26 Feb 2007, 20:56:03 UTC

This is a week in which I hope to make a lot of progress. The SETHI jobs are chugging away on ewen, lando, thumper and sidious, though they'll get a break tomorrow while we make another attempt to install more RAM into ewen. That'll hopefully make things run even better than they have been. At Arecibo I'm reprocessing a tonne (10% more than a ton) of GALFA data too, on five of their machines. When it's all done I should be able to make HI maps of the sky using data from different observing sessions, something that was hard to do previously. So it's a small step backwards in order to make giant leaps in short time.

While all that's going on in the background, I'll be trying to get somewhere on my dust-gas relationship research. I have to figure out the best way to make dust-to-HI ratio maps for several different regions I'm studying. It's just a matter of getting both the dust and the HI data in the same format, so I'm sure I can get it done. Late last week I received the proofs for a paper I wrote that will appear in the Astrophysical Journal in about a month. I sent in my approval, then noticed that one of my figures, possibly the most important one, is about 4 times smaller than I wanted it to be - it's been shrunk to fit in one column of a two-column page, so it looks hilariously unimportant compared to other figures in the paper. I hope it's not too late to try and change it.

Our group meeting was pretty short today. We're getting to the bottom of what's causing the short pulses in new SETI@home data - an engineer at Arecibo is helping us figure it out. Everything else seems to be running well, from what I heard. Hardware donations have been helping us out quite a bit, and now that we're on Hurricane instead of Cogent our internet bill should drop quite a bit too. So we're in good spirits at the moment. I've got two weeks to put my seminar talk together. It's probably about 25% done at this stage, but I know it'll come together soon enough.

NHL looks to be gearing up for the playoff run. I wonder if any more big trades will be made before the deadline, which I think is tomorrow. The Sharks-Flames game on Saturday sure was fun to watch. I haven't seen any games live this year yet but Eric and I went to a couple last year in San Jose (vs Canucks and Flames, my two favourite teams :).

I think I'm going to have to see Sleepytime Gorilla Museum in March. They're a wild band and Matt is good friends with them too, but I'd actually discovered them myself when I lived in Calgary. I remember describing them to my friends as a cross between Henry Cow and Mr. Bungle. If you have friends to whom such a statement makes sense, then you have cool friends!

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Message 523768 - Posted: 26 Feb 2007, 21:02:33 UTC
Last modified: 26 Feb 2007, 21:03:34 UTC


@ Kevin . . . ediT - hope u r well . . .

We're getting to the bottom of what's causing the short pulses in new SETI@home data - an engineer at Arecibo is helping us figure it out.


are we crunchin' those right now - i.e. 05no03ab.1369.5057.11088.3.50_3 ?

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Message 523775 - Posted: 26 Feb 2007, 21:20:05 UTC - in response to Message 523768.


@ Kevin . . . ediT - hope u r well . . .

We're getting to the bottom of what's causing the short pulses in new SETI@home data - an engineer at Arecibo is helping us figure it out.


are we crunchin' those right now - i.e. 05no03ab.1369.5057.11088.3.50_3 ?


The multibeam data recorder was installed in June '06 (or was it July?), so I'd suspect your work unit is still from line-feed data. It sounds like we can remove these pulses from existing data, so hopefully SETI@home multibeam will be moved out of beta soon enough. Even better, future data won't have these pulses at all - Dan's been forwarding us updates on what the engineer at Arecibo is finding, and if I know anything about the Arecibo eng staff it's that they can track down aberrant signals.

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Message 523827 - Posted: 26 Feb 2007, 22:45:11 UTC - in response to Message 523775.

We're getting to the bottom of what's causing the short pulses in new SETI@home data - an engineer at Arecibo is helping us figure it out.

... It sounds like we can remove these pulses from existing data, so hopefully SETI@home multibeam will be moved out of beta soon enough. Even better, future data won't have these pulses at all - Dan's been forwarding us updates on what the engineer at Arecibo is finding, and if I know anything about the Arecibo eng staff it's that they can track down aberrant signals.

Wow!

OK, so any clues for us spectators and crunchers?

Or would that be giving away someone else's thunder?

Regards,
Martin

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Message 523842 - Posted: 26 Feb 2007, 23:11:59 UTC

Not to steal any thunder, but the latest leading hypothesis is that the errant pulses are actually just (military) radar that we are picking up on this new instrument. This is good, as it means it's not a bug in our system, and there may be known methods of removing these signals. Jeff/Josh/Dan/Eric and staff at Arecibo are looking into it (I'm just overhearing their conversations here at the lab).

- Matt
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Message 523915 - Posted: 27 Feb 2007, 2:45:26 UTC - in response to Message 523842.

... the latest leading hypothesis is that the errant pulses are actually just (military) radar that we are picking up on this new instrument...

Then it looks like Michael B is the leading contender for best guess.

(And I was assuming that Arecibo was somewhere very remote...)

Good luck for in the hunt and cure. I hope the offending source can be switched off or otherwise shielded into oblivion.

Cheers,
Martin

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Message 523931 - Posted: 27 Feb 2007, 3:10:23 UTC - in response to Message 523915.

... the latest leading hypothesis is that the errant pulses are actually just (military) radar that we are picking up on this new instrument...

Then it looks like Michael B is the leading contender for best guess.

(And I was assuming that Arecibo was somewhere very remote...)

Good luck for in the hunt and cure. I hope the offending source can be switched off or otherwise shielded into oblivion.

Cheers,
Martin


Arecibo is indeed quite remote, but you can see the Atlantic Ocean if you are standing on its receiver platform, which is about 150 metres above the lowest point of the reflecting surface. So unfortunately it sees radar signals from SJU (San Juan Airport) as well as other radars that, among other things, try to curb drug trafficking. I'm not so sure what we're seeing is radar, though, since it doesn't seem to show up in other data measured with ALFA. Here's an excerpt of one email we got earlier (I don't think I'm giving away trade secrets here):
> From the separation between nulls in the spectrogram,
> I'd judge that the pulse width (if at least somewhat rectangular)
> would be about 13 microseconds. That's about twice the
> width of the typical radar pulses that plague us so severely,
> so I think we can rule out some peculiar side effect of the
> radar interference as the cause.

If you guys are keeping track of guesses, put me down for "hard drive glitches". And no, I don't know the answer ahead of time.

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Message 524343 - Posted: 28 Feb 2007, 0:13:59 UTC - in response to Message 523931.

If you guys are keeping track of guesses, put me down for "hard drive glitches". And no, I don't know the answer ahead of time.

What? You can't do predictive caching?!

If radar is a well known problem, then I would guess that it would get very quickly recognised and identified. Still always a possibility for some new type of radar.

Looking at those FFTs, you could imagine that there is a time delayed ghost trace of each group of pulses suggesting multipath pickup.

Very interesting that no other projects notice the problem. However, would they notice that type of interference with their observations?

More clues needed for anything other than wild "buckshot" guesses.

Good luck with the hunt.

Regards,
Martin

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Message 524600 - Posted: 28 Feb 2007, 17:40:47 UTC - in response to Message 523842.
Last modified: 28 Feb 2007, 17:42:14 UTC

Not to steal any thunder, but the latest leading hypothesis is that the errant pulses are actually just (military) radar that we are picking up on this new instrument. This is good, as it means it's not a bug in our system, and there may be known methods of removing these signals. Jeff/Josh/Dan/Eric and staff at Arecibo are looking into it (I'm just overhearing their conversations here at the lab).

- Matt

That figures, Berkeley gets Military radar and out here in Yermo CA, We get the Militaries Sonic Booms from Nellis AFB(Las Vegas NV). At least You're not getting equipment problems, As the Radar should be something that can be eliminated I'd think. Good Luck guys and keep up the Good Work there at Berkeley.
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Message 524717 - Posted: 28 Feb 2007, 22:50:06 UTC - in response to Message 524600.
Last modified: 28 Feb 2007, 22:56:51 UTC

What a day...ewen got hung up sometime overnight, and I had to reboot Eric's machine twice this morning too. My SETHI jobs got froze during the process, so I had to restart them, and they're paused right now while ewen resyncs itself, or something. Good thing I'm getting so much done on my GALFA data. Since Sunday I've processed about 115 days of data, using 6 linux machines at Arecibo. I have about 30 days to go for the Fall semesters of TOGS, our Turn On GALFA Survey. I think I'll be done them by tomorrow morning.

I can't believe Ryan Smyth got traded from the Oilers. That came out of nowhere. I'm pretty happy the San Jose Sharks got Bill Guerin. I'd still rather see Calgary or Vancouver go to the Stanley Cup final, but if the Sharks went that far it would be good for hockey in Northern California. The skating rink here in Berkeley went bankrupt, and the Sharks organization owns a few rinks around the Bay Area. It would be good if they could rescue Berkeley's Iceland, though from what I hear they would charge a lot more for recreational hockey teams to rent the ice. It would be ideal if UC Berkeley could step in, but I don't see that happening. I could rant on and on about how the city and the university don't get along, but what's the point?

We had a short science meeting this morning. Still tracking down the cause of pulses in ALFA seti@home data. If it was radar, why wasn't it seen in the old data? Radar signals have plagued Arecibo for ages, and they have documented RFI very well over the years. We'll have to correct any data that gets recorded before we determine any realtime mitigation techniques, but ideally in the long run this errant signal will be eliminated before it gets to the data recorder. Everything else is progressing well. I processed a few donation cheques before ewen hung for the second time, including one for $2000. So you can see that on our donation tracking pages. A nice way to end off the month.

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Message 527293 - Posted: 6 Mar 2007, 14:01:46 UTC - in response to Message 524717.

... I processed a few donation cheques before ewen hung for the second time, including one for $2000. So you can see that on our donation tracking pages. A nice way to end off the month.


Yes, it's great that people are so generous.

Thank you to all who have donated money and hardware.



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