I've checked my wus which I have crunched so far (at least since April 1) and I made an interesting observation. Since April 17 there is a strong increase of noisy wus. Those wus result in the warning

4.32

SETI@Home Informational message -9 result_overflow
NOTE: The number of results detected exceeds the storage space allocated.


According to Paul D. Bucks (excellent) documentation: This informational messages tells you that the analysis of this particular Work Unit has resulted in so many, Gaussians, Pulses or Triplets that the processing is being cut short and the work unit requires further analysis by the mother ship (UC Berkeley).
And: This is not an error. This is not a bad Work Unit. It is, however, a Work Unit that may have so much noise that it is not worth looking at at all, or that it may be the signal from ET. Most likely it is the former and not the latter. Sorry about that ...

Here are the numbers:

Wus crunched April 1 - 17: 341
"noisy": 31
Percentage: 9.09 %

Wus crunched April 17 - 22: 57
"noisy": 19
Percentage: 33.33%

ET or just dirty tapes from Arecibo???

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<explanation class="POOMA">

I think we've out-crunched all of the recent data from Arecibo (say 2004 through present), so now we're getting older WUs from out of the closet - Maybe even re-crunching Classic WUs as BOINC/SETI WUs. Most likely over that time the quality of the older data is degrading. So my guess (until a Dev or Admin says I'm totally out of my mind) is that the tapes that the WUs were stored on probably got some exposure to dust and magnetization, so that's why we're getting weird WUs.

</explanation>

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> I think we've out-crunched all of the recent data from Arecibo (say 2004
> through present), so now we're getting older WUs from out of the closet

Not quite. It's more likely that we've worked through those tapes in the box nearest the closet door, or those in the latest Fed-Ex box!

A human pulls a few tapes 'at random' from the 'todo' list for whatever is physically convenient (or possibly interesting).


> - Maybe even re-crunching Classic WUs as
> BOINC/SETI WUs. Most likely over that time the quality of the older data is
> degrading. ...

???

Tapes are used precisely because they have excellent long term storage lives (decades). There is more a problem of the tape DRIVES becoming obsolete before the magnetic data is lost. (Compared to CD-R that might last as little as 3 or 4 years if you're lucky (:-((

If any Classic crunched WUs are to be reworked, I would expect them to use a new dedicated Boinc client to extract additional science from the data.


Regards,
Martin

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> I think we've out-crunched all of
> the recent data from Arecibo (say 2004 through present), so now we're getting
> older WUs from out of the closet -

No, Currently the splitters are processing data from 14Jan05 and 26Jan05, So the data is about 3 months old.

Anothe post somewhere indicated that the is a degree of randomness in the tape selection - pulled from a box next to a desk.

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> I've checked my wus which I have crunched so far (at least since April 1) and
> I made an interesting observation. Since April 17 there is a strong increase
> of noisy wus. Those wus result in the warning

I've seen the following batches producing noisy ones here:

5 x 01fe05aa.3892.14641.398584.x

2 x 23ja05aa.25485.x

1 x 22ja05aa.20998.32898.329836.x
3 x 22ja05aa.20998.27408.784646.x
2 x 22ja05aa.20998.25394.73576.x
3 x 22ja05aa.20998.25346.404820.x
2 x 22ja05aa.20998.25152.x
1 x 22ja05aa.18802.7634.928404.x
2 x 22ja05aa.18802.2130.417318.x

2 x 20ja05ab.18441.x
1 x 20ja05ab.18441.18512.790908.x
3 x 20ja05ab.18441.18274.348594.x
1 x 20ja05ab.18441.22482.436076.x

1 x 16ja05aa.18552.32432.403412.x

2 x 07se04aa.10251.x
2 x 07se04aa.10251.27265.723566.x
2 x 07se04aa.10251.27217.1047142.x

Seems to be a spikes of noise on:
01 Feb 2005 (5 noisy units)
22 Jan 2005 (14 noisy units)
20 Jan 2005 (7 noisy units)
07 Sep 2004 (6 noisy units)

Don't know what it means though. Maybe just someone driving past the dish in their camper van and operating the microwave at the same time ... ;-)

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> Anothe post somewhere indicated that the is a degree of randomness in the tape
> selection - pulled from a box next to a desk.

But, once the tape has been "pulled", if it contains "noisy" parts we will see a bunch of -9 work units. If you look at the old mapping table on the SETI@Home Classic site you will see long streches where the data captured is ALL bad.

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Add to it:

26ja05ab.16009.4833.504824.1731

(http://setiweb.ssl.berkeley.edu/workunit.php?wuid=13604805)

I was actually about to post a new thread with a question why a successful unit too only 100 secons of work, when I stumbled across this thread and cross-checked the result output for "my" WU.

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