data and distance for pulses in space

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merle van osdol

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Message 1555962 - Posted: 12 Aug 2014, 23:49:55 UTC

How much data could be contained in one of these pulses? How far out in light years is astropulse 'good for'?
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Message 1556049 - Posted: 13 Aug 2014, 3:58:06 UTC

From what I understand we are looking for a carrier signal more than an actual message.
I am unsure of the distance the frequencies we are observing might be viable.
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Message 1556060 - Posted: 13 Aug 2014, 5:07:13 UTC - in response to Message 1555962.  
Last modified: 13 Aug 2014, 5:08:12 UTC

How much data could be contained in one of these pulses? How far out in light years is astropulse 'good for'?


When we think about these things we have to take all kinds of things into account.

MultiBeam tasks are looking for a thing. AstroPulse tasks are checking for something else.

But both analyses are run on the same recorded data. The same "signal" is present. AstroPulse has (reportedly) picked-up the "signal" of at least a couple of known pulsars. I don't know which pulsar was heard because I'm pretty sure nobody ever said. There have been no reports (that I am aware-of) that MultiBeam tasks have picked-up a pulsar. (Why that is will make more sense in a minute.)


But if a Google search is to be trusted, the closest known pulsar is 280 light years away. Of course, you would expect that a pulsar is a very strong RF source (or not if it is not an RF-emitting pulsar and some aren't). I have no idea what the effective radiated power of a pulsar might be, and I'm not sure how to even find-out what minimum power Arecibo can "hear."

So, obviously, the power of the signal *at the antenna* depends-on not only the distance, but also the power of the radiation in the first place.

All of that was to explain why I don't think it is really possible to know the answer to your question except as a function of the signal-to-noise ratio of the weakest link in the radio-telescope's signal chain. Then you'd have to assume a signal strength and *then* speculate about the maximum distance an object with that specific power would have to be in order not to be heard.

The worst part of all of this is that the signal *must* be "discoverable" by the analyses that are done.

Here's a stupid explanation, but it's all I can think-of. If you stick an antenna in the air you can pick-up AM / FM / CB / HAM. You can also pick-up lightning. You can also pick-up the background noise from the big bang. But you won't hear an AM radio station unless you were using an AM-band radio receiver. So, if a really strong FM radio station were right next door to you, and you're only listening for AM, you hear nothing. But if you were listening to AM or shortwave and there was a lightning strike next door you'd hear that, too.

So, "How far out" you can hear a lightning strike when you are trying to listen to a baseball game on the AM radio depends on a lot of things; not least of which is whether or not you even have an AM radio.

As to how much information could be in a pulse --- there's no telling. No way at all to know except for a theoretical limit based on some quantum-measurement or other, all of which I'm sure is quite beyond my understanding. I feel sure there must be a downward time limit... like you couldn't encode Morse Code faster than the speed of light. Well, someone might, but we couldn't amplify it and listen to it. And how "tightly packed" the information is and how it is packed in there is going to determine how the "interstellar medium" is going to affect it.

But as another really bad analogy, have you ever heard of a "micro-dot?" If you're reading a book and see a period, you could stick it under a microscope and see if it is a micro-dot. But you have to see the period to begin-with to start looking for all of the information that might be in the micro-dot.

How much information could be in a micro-dot?

I've seen IBM spelled-out using individually arranged atoms. There could be a lot of information there, or it could just be a period.

So, I know I haven't answered your questions, but I hope you have a more multidimensional view of the problem.

So AstroPulse is listening for a "lightning strike" across a wide band of frequencies. Or maybe a really fast burst of a radio signal in the band it is listening-to.

And again, it may be nothing but a "flash." It may contain no intelligent information at all, just as a distress beacon on a life vest does not contain any information. The blinking just means, "Look here!"

It's a complicated subject that I have explained poorly.

EDIT: You might get a more scholarly and less wildly inaccurate answer by asking in the Science section of the message board.
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Profile James Sotherden
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Message 1556061 - Posted: 13 Aug 2014, 5:08:50 UTC

They also have found at least two new pulsars with doing Astro Pulse work.
[/quote]

Old James
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Message 1556074 - Posted: 13 Aug 2014, 5:32:25 UTC - in response to Message 1555962.  

The reason we are looking for pulses is because the Radio Telescope is scanning the sky in various patterns depending on what the main work it's doing happens to be. Even if the scope isn't moving itself, the Earth's movement has it sweeping the sky continuously.

So any constant signal that it picks up will appear as a "pulse".

Now the clever part is mapping the whole sky, and finding a spot where there is a consistent signal, or at least a regular and otherwise unexplained one. That can then be investigated further by a targeted scan.

What info could it contain? Could be no more than a beacon going Beep Beep Beep. Or it could have a TV signal encoded into it. Either way would only appear as a "Signal" to the SETI search, but if it was a significant one it would get further investigation.

How far away? Depends on the power of the signal. I guess it's fair to say that the most likely candidates would be local(ish) stars just because of the power that would be needed to transmit a signal further, and why would anyone send a hugely powerful signal that wont be received for a million years?

Ian
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Message 1556104 - Posted: 13 Aug 2014, 7:34:32 UTC - in response to Message 1556074.  



So any constant signal that it picks up will appear as a "pulse".



Ian, I believe they are correcting for Earth's rotation and what we are doing in part is attempting to compensate in almost endless fashion any possible relative movement. That's why the need for staggering amounts of computer-power.

They are looking at the data for things that can be "resolved" into a pulse.
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merle van osdol

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Message 1556105 - Posted: 13 Aug 2014, 7:43:16 UTC

Oh Boy. What a response! I understand it now. In my way of understanding. I wouldn't want to go deeper with a more technical explanation because it would probably jamb my brain like with quantum mechanics and all the modern physics of spacetime, etc. Thanks, thanks, thanks.

Maybe after digesting this stuff here, I'll have clearer questions to formulate.
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merle van osdol

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Message 1556115 - Posted: 13 Aug 2014, 8:04:41 UTC - in response to Message 1556105.  

I have been with seti since before there was boinc. One thing it has proven to my satisfaction is that ETI is a delicate, fragile and hard to find commodity at least in our local area of the Milky Way.

What are the likelyhoods/probabilities that in the next 100 years we will have developed much more powerful radio telescopes that will be able to reach much further into our galaxy?
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Message 1556122 - Posted: 13 Aug 2014, 8:53:48 UTC - in response to Message 1556115.  



What are the likelyhoods/probabilities that in the next 100 years we will have developed much more powerful radio telescopes that will be able to reach much further into our galaxy?


Odds?

It's all about the money. The technology already exists.
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Message 1556124 - Posted: 13 Aug 2014, 9:04:46 UTC - in response to Message 1556122.  

The ALMA radiotelescope in Chile has 66 antennas but is not used for any SETI search. Scientists do not care about SETI, save a small minority.
Tullio
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Message 1556125 - Posted: 13 Aug 2014, 9:11:17 UTC - in response to Message 1556115.  

I have been with seti since before there was boinc. One thing it has proven to my satisfaction is that ETI is a delicate, fragile and hard to find commodity at least in our local area of the Milky Way.

What are the likelyhoods/probabilities that in the next 100 years we will have developed much more powerful radio telescopes that will be able to reach much further into our galaxy?

The Square Kilometre Array. ;-)

Cheers.
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Message 1556129 - Posted: 13 Aug 2014, 9:32:06 UTC - in response to Message 1556125.  

I doubt very much it will be used for SETI.
Tullio
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merle van osdol

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Message 1556133 - Posted: 13 Aug 2014, 9:45:26 UTC - in response to Message 1556129.  
Last modified: 13 Aug 2014, 9:47:23 UTC

It's sad that so little effort is made to advance seti by the scientific community. I personally think it is one of the most important scientific endeavors possible. We do not know how much time we will have here on earth. If we can communicate with others that may greatly increase our chances of survival here.

Thanks for all of the responses. It gives me much to ponder.
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Message 1556137 - Posted: 13 Aug 2014, 10:02:38 UTC - in response to Message 1556129.  

I doubt very much it will be used for SETI.
Tullio

I believe it will.

What will the SKA be used for?

Radio astronomers will use the SKA to understand how stars and galaxies formed, and how they evolved over time, and perhaps to detect life elsewhere in the Universe.

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Message 1556187 - Posted: 13 Aug 2014, 14:33:44 UTC

When you build a new telescope or a new particle accelerator, costing maybe billions of dollars, politicians expect some results in a short time, so they can tell people; This is what we spent your money for. So a research like SETI, which may go on for hundreds of years, is not a top priority. We are lucky if we get some data from a piggyback on research done at Arecibo or Green Bank, or maybe Parkes, where they found some extremely powerful radio bursts from other galaxies,a discovery confirmed at Arecibo.
I watched a streamed press conference of NASA discussing the search for exoplanets by a new generation of telescopes, including the JWST. SETI was not even mentioned.
Tullio
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Message 1556748 - Posted: 14 Aug 2014, 15:52:59 UTC - in response to Message 1556115.  

What are the likelyhoods/probabilities that in the next 100 years we will have developed much more powerful radio telescopes that will be able to reach much further into our galaxy?

What seems likely to me (but I could be totally wrong) is that in the next hundred years we will develop new ways of modulating our own transmissions, ways that would not be detected by the current Seti searches/scans, and Seti projects will start looking for those methods and also reexamine previously collected data for them.
David
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Waiting for a message from a small furry creature from Alpha Centauri.

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Message boards : Number crunching : data and distance for pulses in space


 
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