Each "tape" (historically a real tape, but these days a file on the disk used to move data fro the telescope to the project) contains 50Gb of data. This is split twice, once to generate the "Astro-Pulse" work units, and then again to generate the "Multi-Beam" work units. An AP work unit is larger, and has far less overlap than an MB work unit. The tapes are loaded and processed in batches, the ratio of AP:MB is fixed (I can't remember what it is), so there will always be far fewer AP work units than MB.
Of course you can in your options only run "AP" or "MB", or take what comes. Generally if you select only to run AP you will run out of work for a few days a week - until a new batch of tapes are loaded and splitting on them commences.

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Bob Smith
Member of Seti PIPPS (Pluto is a Planet Protest Society)
Somewhere in the (un)known Universe?

Hello. This is my first post as I am new to the SETI family.

While reading this thread and getting a better understanding of what I have volunteered for, it struck me as being very strange that the aliens that visit earth have not tried to communicate. At least, not that we are aware of.

If the many reports of abductions of humans and sightings of UFO aircraft all over the world for eons, it seems that they could easily communicate with us if they wanted to do so.

It is obvious the ones that visit Earth are far more advanced than we are. Perhaps they see that many of the people that live on Earth are willing to shoot first and ask questions later. What a shame since they are in such close proximity.

I am still confused how SETI will know if there is a possible hit on my pc unless we are sending a short message to alert someone about it.

The obvious answer is that we are not being visited by aliens or alien spacecraft. Therefore there is no urgent need for some sort of alarm system to alert anyone immediately.

SETI@home is only listening for a signal. SETI does this by breaking up the tasks it sends to your PC out to at least two people. Once both results come back and if the match closely, the canonical result gets recorded into the Master Science Database. If the result is interesting enough, it might get selected for re-observation in an attempt to see if there are any repeat signals from the same location.

If the result is interesting enough, it might get selected for re-observation in an attempt to see if there are any repeat signals from the same location.

If this process takes a year or so it isn't likely that it will be repeated unless it is a spurious signal. Why are these signals interesting, how many have been checked out subsequently, what are the results ??

These are not likely to be a spurious signals since we have been listening for 50 years and have heard nothing. It may well be a randomly beamed message from a civilization that doesn't know that we are here. If it is a slewing beam it is not likely that we will see it again.

Any interesting signal should be judged immediately as to whether or not it contains a message that indicates intelligence. A beamed signal may not be repeated--It seems to me that that is the only type of signal that we might receive from an intelligent civilization and it probably would not be repeated at the time that Arecibo rotated to that portion of the sky.

You're not wrong William, but how do you verify that a signal was the real deal and not just some sort of noise or anomaly?

Thank you for the comment "no-name" volunteer tester.

I see I did not complete my thought and omitted saying, "If the reports are true...."

The jury is still out for me on whether or not we have had any visitors from outer space but I do know that many things occur that are difficult to explain. It appears those who report seeing a UFO (up close and personal or otherwise) are adamant about what happened or what they saw and nothing will change their minds even though there may be a perfectly rational explanation to what occurred.

Thank you again.

The jury is still out for me on whether or not we have had any visitors from outer space

Actually.. no. The only people who believe we're being visited are those with a predisposition to believing stories without facts to back them up.

but I do know that many things occur that are difficult to explain. It appears those who report seeing a UFO (up close and personal or otherwise) are adamant about what happened or what they saw and nothing will change their minds even though there may be a perfectly rational explanation to what occurred.

The beautiful thing about evidence-based facts is that they don't require those who simply "believe" in something they can't explain to be true. In every single case there is a more naturalistic explanation to any alien visitation story if one simply knows where to look.

People who choose to believe regardless of facts are going to be the same as those who believe in ghost stories, angel stories, out-of-body experiences and the like. If no amount of facts or evidence is going to change their minds as to what they believe, then there's no point in discussing anything with them or trying to make them better understand what they might have seen or experienced.

how do you verify that a signal was the real deal and not just some sort of noise or anomaly?

That's a good question; but does it matter if the signal is one time or continuous ?

Because of aircraft and satellites I suppose that a lot of one time signals might be picked up. Continuous, Earth-originated signals should be able to be eliminated and a clutter map established from known sources (Earth based, pulsars etc). As for the others, it might be difficult but we would have to eliminate based on frequency of transmission (gigahertz) and earth related content (languages, radar, tv etc).

Here's what I surmise --do you think i might be off-track:

It is not likely that there would be terrestrial broadcasts of "we are here" types of information.
What might these be if they came from another planet. I would expect a counting out of the prime numbers followed by another sequence (maybe the first 50 numbers of Pi) this repeated several times and then some form of a map that would identify the location of the home planet. I expect that people steeped in the cosmos could figure out how to do this --perhaps by using constellations to triangulate. They might also suggest a specific frequency on which to reply.

Perhaps a dialogue could be started that might last many decades or centuries. Initially it might be an exchange of a primer on a language and grammar rules.

how do you verify that a signal was the real deal and not just some sort of noise or anomaly?

That's a good question; but does it matter if the signal is one time or continuous ?

I would tend to think it does matter. But maybe I'm wrong. I'm certainly not in a position to argue otherwise.

What might these be if they came from another planet. I would expect a counting out of the prime numbers followed by another sequence (maybe the first 50 numbers of Pi) this repeated several times and then some form of a map that would identify the location of the home planet. I expect that people steeped in the cosmos could figure out how to do this --perhaps by using constellations to triangulate. They might also suggest a specific frequency on which to reply.

I'm sure it's possible. The question is, is that what SETI is looking for in the tasks they send out to us?

Welcome to the project AgreeingSoup:)

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rOZZ
Music
Pictures

The question is, is that what SETI is looking for in the tasks they send out to us?

I am really not sure what is actually being done in this SETI process.

My impression is that we are initially looking for strong signals which are confirmed strong by three crunchers. Ostensibly these are being flagged for the future to see if they are still there during the next go-round at Arecibo. If they are not still there then maybe they are discarded or taken off the target list.

After that I would expect them to be demodulated or otherwise examined for any content in the carrier wave. This is where true intelligence has to be applied to determine if there is any type of message or graphic embedded. Since we have found no one I conclude that either this isn't being done or there is no intelligence in any of the persistent signals.

This may be way off base from what is actually being done. I still wonder whether a computer program couldn't be written to examine each work unit as it comes in off of the antenna for any type of embedded signal or meaningful pulsation. Maybe a linguist could characterize the power spectrum of any likely candidate of any possible language. Possible video frames could also be investigated --assuming data embedded in the signal.

There is an old joke about a drunkard looking for his lost keys at night under a lamp post. When some helper asks him: have you lost your keys here? No, he says, down there. And the helper asks: then why do you search for them here? Because there is more light, he answers. I think we are doing the same.
Tullio

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Looking for repeatable signals from a given location in the sky.
Not necessarily strong signals, but those that are there, and of non-terrestrial, unknown origin.

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Bob Smith
Member of Seti PIPPS (Pluto is a Planet Protest Society)
Somewhere in the (un)known Universe?

Maybe we're looking for a needle in a haystack but the important thing is we're looking!

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rOZZ
Music
Pictures

We are making a number of guesses.First, it is not sure that ETIs use radio waves. Second, it is not sure that they transmit at the frequency we listen to. Maybe they use gravitational waves or neutrinos or something we can't even imagine.
Tullio

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NASA: SOS call from distant galaxy

The signal was detected in January of 1998, however, it took months to decode the message.

Hmmm, this is the first I hear about that.

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rOZZ
Music
Pictures

That's because NASA released no such information. The site obviously has a pro-alien UFO bias which, like so many others, contends alien UFOs are being hidden from us.

The obvious questions are: where are the linked sources? What has lead them to believe their reports are true?

That's because NASA released no such information. The site obviously has a pro-alien UFO bias which, like so many others, contends alien UFOs are being hidden from us.

The obvious questions are: where are the linked sources? What has lead them to believe their reports are true?

Sites like that should be forbidden imo, they're driving people crazy with their assumptions *sigh*

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rOZZ
Music
Pictures