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Quietest SETI unit recorded? Some of these WUs must exist...
Quietest SETI unit recorded? Some of these WUs must exist...
General requirements for a quiescent WU: 1. No Gaussians 2. No Triplets 3. No 'spikes' of any kind that would show up on the meter 4. No 'Doppler effects in the signals = I hope I have covered all the bases... |
#2
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"Max Power" wrote in message ...
Quietest SETI unit recorded? Some of these WUs must exist... General requirements for a quiescent WU: 1. No Gaussians 2. No Triplets 3. No 'spikes' of any kind that would show up on the meter 4. No 'Doppler effects in the signals = I hope I have covered all the bases.. "Quietest" WU is probably one put together from a session after someone tripped over a receive waveguide... |
#3
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Quietly we read , unable to
contain our credulity we realized that Max Power said this: Quietest SETI unit recorded? Some of these WUs must exist... General requirements for a quiescent WU: 1. No Gaussians You can fit a Gaussian to random noise, it just would be a very poor fit. You would have to specify how poor for this post to make any mathematical sense. 2. No Triplets 3. No 'spikes' of any kind that would show up on the meter Unless all readings are identical you will also get spikes. 4. No 'Doppler effects in the signals = I hope I have covered all the bases... Having said the above I had a very flat WU that completed in 6 hours when they normally take 12 or more on my computers. It had a very small result.sah file. Wish I'd kept a copy. -- Bill Jillians |
#4
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In article ,
Bill Jillians wrote: 1. No Gaussians You can fit a Gaussian to random noise, it just would be a very poor fit. You would have to specify how poor for this post to make any Not in S@H. It tries to fit so many gaussians to each work unit that approximately one of them will be good enough to report to Berkeley. That's true of all the detection modes; they are all calibrated for the order of one false positive per work unit. What will stop gaussians is an unacceptable angle range, that stops them being tested for. Also note that there is no absolute amplitude information in the work unit so connecting the feed to any noise source will produce similar statistics. |
#5
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David,
I must respectfully disagree. I don't know about Boinc, but in S@H classic, there is a power threshold below which Gaussians will not be reported, no matter what the "fit" may be. I believe that the Gaussians must also be of the correct duration, to match the results of the Arecibo antenna "sweeping" across a point radio source in the sky as Earth rotates. I have run dozens of WUs that SETIspy clearly showed with no Gaussians at all, just before I sent them in for the record. Spikes can certainly be just noise, and the occurrence of spikes would be meaningless without duplicating the results later; even then, it could be just a natural radio source, such as a pulsar. -- (Replies *will* bounce, unless you delete the letter A from my email address) Cheers, Red David Woolley wrote: In article , Bill Jillians wrote: 1. No Gaussians You can fit a Gaussian to random noise, it just would be a very poor fit. You would have to specify how poor for this post to make any Not in S@H. It tries to fit so many gaussians to each work unit that approximately one of them will be good enough to report to Berkeley. That's true of all the detection modes; they are all calibrated for the order of one false positive per work unit. What will stop gaussians is an unacceptable angle range, that stops them being tested for. Also note that there is no absolute amplitude information in the work unit so connecting the feed to any noise source will produce similar statistics. |
#6
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In article ,
red wrote: I must respectfully disagree. I don't know about Boinc, but in S@H classic, there is a power threshold below which Gaussians will not be reported, no matter what the "fit" may be. I believe that the Gaussians Having two degrees of freedom makes means that you can trade one against the other in setting the threshold, but the fact still remains that if the threshold weren't set to produce lots of false positives from noise artefacts there ould only really two other possibilities, both of which would have major consequences for SETI: a) We're are seeing huge numbers of non-repeating genuine ETI signals; or b) There are natural phenomena that produce much narrower band signals than we had previously assumed. The former would imply proof of ETI and the latter would indicate that the search strategy is unworkable. Incidentally, if I remember correctly, there is actually a technical paper that discusses the threshold selection strategy for pulses. |
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