SETI E.T. Search Radio Interference ??

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Message 1789484 - Posted: 22 May 2016, 15:52:41 UTC
Last modified: 22 May 2016, 16:52:06 UTC

Sunday May 22 2016, 7:49 AM

Hi All,

I have come across an anomaly in regard our search for E.T. thruout the cosmos, and need enlightenment from my peers and those much smarter who may live in a cave atop a high mountain. :) I'm a lowly microwave engineer and I do not have a string of "alphabet soup" after my name, only an "MSEE."

Here is the puzzle I see and need help with.

Shown below is a link to a plot of plot of Earth's atmospheric transmittance (or opacity) to various wavelengths of electromagnetic radiation.



Radio waves are the longest wavelengths, the lowest frequencies, and have the lowest energy in the electromagnetic-band. Astronomers using radio to study phenomenon from deep space, such as SETI, use a frequency range of 300 GHz to 30 MHz, or 10 cm to 10 m terms of wavelength.

I've detailed the difficulty of our search for E.T. in other posts in various SETI groups. Briefly, I postulated that signals from other intelligent life forms would likely be VERY weak and below the thermal noise floor of -174 dBM/Hz. Such signals could only be detected if they were repetitive transmissions, i.e., a digital string sent repeatedly, over and over, and then verified as valid using a CRC code, i.e., a "cyclical redundancy code." It is possible, using a signal integration technique, to detect repetitive signals 20 or even 30 dB below the thermal floor. Needless to say but THESE signals will be WEAK, very WEAK. In trying to detect them we are at the very limits of our technical ability.

Radio telescopes use the frequency of 1420 MHz, 1.42 GHz, or 21.1 cm in terms of wavelength in our search for E.T.

The noted physicist, Stephen William Hawking, CH, CBE, FRS, FRSA, an Englishman, and the genius sadly confined to a wheelchair for life, has said: "1420 MHz is a 'sweet spot' on the cosmic radio dial." I heard this interesting comment on his new TV series titled "GENIUS."

OK, are you with me so far? 1.42 GHz is a "sweet spot" in terms of "low galactic noise," Can we agree?

It is also described as the "Hydrogen line", and the "21 centimeter line": it is precisely 1420.40575177 MHz, and used by many radio telescopes including The Big Ear in its discovery of the Wow! signal.

The anomaly I mentioned above is this. I suggest you do a web search, using whatever site you choose, like Bing, Google, etc. Type in the search term of "1.42 GHz," w/o the parenthesis.

What do you see? Here are links I saw: eMac, Power Mac, Mac mini, Intel, I-Book, power mac, Apple All-in-one, and many more links. ALL of these had ONE THING in common. Each one TOUTS its use of 1.42 GHz !! Huh? Why?

I cannot, for the life of me, figure out WHY this is so? Why isn't this critical radio frequency "sweet spot" OFF LIMITS to makers of computer chips?

Consider that possible very weak signals from deep space are actually coming from advanced civilizations many light years away and are likely buried deep in the noise, aren't these signals being BURIED beneath a ton of 'noise' generated by millions of computer chips radiating into the sky? Unbelievable!

Why do chip makers and computer companies use THIS frequency? Why not one AWAY from the "sweet spot?"

Here is one other issue to ponder. If we grant the fact that 1.42 GHz is the "holy grail" in our quest to find E.T., and that other advanced civilizations know this too, then, as I see it, there are only TWO possible reasons to transmit on this frequency. First, you transmit so others will, hopefully, hear you, and confirm, in their minds, the existence of extraterrestrial life. Or, second, you use this "low galactic noise" frequency as your #1 "comm channel" because your civilization is, like "star fleet", scattered hundreds of light years apart throughout the cosmos and you use this critical frequency to give others of of YOUR kind the best chance to "hear" you calling them. You don't care about "aliens" like those primitives on planet Earth. :)

Wouldn't it make more sense, for US and THEM, to maybe transmit for awhile and then listen for a while? All we do is listen and maybe others are just listening too? :) Maybe one of us should TRANSMIT, i.e., SAY SOMETHING, on occasion? We're looking for THEM but not giving them a chance to find US? Why is this?

Can anyone enlighten me on this?

Stay here on Earth. It's the only planet with DARK CHOCOLATE !!

Thank you,
River Song (aka Linda Latte on planet Earth)
"Happy I-Phone girl on the GO GO GO"
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Message 1789499 - Posted: 22 May 2016, 16:48:57 UTC

The ALMA array in Chile works in the millimeter range being atop a 5000 meters high plain. It has 66 antennas and is the most powerful radiotelescope on Earth. Unfortunately, it is not available to SETI.
Tullio
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Message 1789573 - Posted: 22 May 2016, 19:42:26 UTC - in response to Message 1789499.  

Personally, I don't recommend intentionally transmitting to what may be a hostile alien race, with little regard for our lives and well being. If we could detect earth-like worlds orbiting alien stars, with primitive life, then those are the types of planets that we would be most interested in colonizing -- and that's how aliens will see us, as primitive life on a hospitable world, fit for colonizing.
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Message 1789590 - Posted: 22 May 2016, 20:54:57 UTC - in response to Message 1789573.  
Last modified: 22 May 2016, 20:55:56 UTC

Personally, I don't recommend intentionally transmitting to what may be a hostile alien race, with little regard for our lives and well being. If we could detect earth-like worlds orbiting alien stars, with primitive life, then those are the types of planets that we would be most interested in colonizing -- and that's how aliens will see us, as primitive life on a hospitable world, fit for colonizing.


An interesting reply that makes sense, sadly. Based on what I've learned about how "sacred" our SETI search frequency is, it seems possible that all SETI has been recording these past many years is "chip noise" generated by millions of Apple computers and Intel processors. :(

Fairy Tale:
A long time ago, there lived a woman.
She did not nag, bitch, or rant.
But, it was just that one day.
And it was a long time ago. :)
The End
River Song (aka Linda Latte on planet Earth)
"Happy I-Phone girl on the GO GO GO"
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Message 1789591 - Posted: 22 May 2016, 21:05:53 UTC
Last modified: 22 May 2016, 21:10:12 UTC

Radiotelescopes are usually located in radio-quiet zones to prevent interference, ie Green Bank's location was chosen as it is surrounded by hills. There are special restrictions in place ie no cell phones, diesel vehicles only (no spark plugs). Any machine noise in the area would be either below the horizon of the telescope or not be concentrated by the dish; it would have to strike the receiver directly and thus, at such a distance with inverse square propagation would be very weak perhaps even below the noise threshold. That frequency range doesn't bounce off the ionosphere either so wouldn't hit the dish by reflection.

So, I don't think it's much of an issue. I'm sure it would have been taken into account! :^)
“Never doubt that a small group of thoughtful, committed citizens can change the world; indeed, it's the only thing that ever has.”
--- Margaret Mead

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Message 1789767 - Posted: 23 May 2016, 13:53:46 UTC

What I am thinking is if we did transmit, where would we point it, and what would be our time frame for a reply? To me, that would only make sense a few light years out. We could target some of the exo-planets we have found in the Goldilocks zone, but even if we sent out signals, and they replied directly back, it would take years, and our radio telescopes may not be pointed at the same place for all that time. You could re-point telescopes in that direction at the earliest possible reply time, but how long would you listen before shifting resources? What we are doing is certainly difficult, making a needle in a haystack easy by comparison. I fully understand that this search may take thousands of years, or may never be successful. On the other hand, we know where an alien civilization isn't broadcasting, or at least during the time Arecibo is focused on a possible target. If we either passed, or haven't gotten to a signal source by a few seconds, we would miss a signal unless it was repeating, such as radio and TV broadcasts from earth. I am much happier with the new targeted exo-planet data. It still make take a very long time, but chances are much greater of a possible success, although certainly not assured.

Steve
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Message 1789768 - Posted: 23 May 2016, 14:04:52 UTC - in response to Message 1789591.  
Last modified: 23 May 2016, 14:56:09 UTC

Monday May 23 2016, 6:57 AM

It is a SAD thing that NOTHING is "holy" in our society because of commercialism; i.e. the need to make more and more $$ at the expense of anything else. In respect of the lifes work and memory of Carl Sagan and others behind SETI their work is more important, IMO, than computer chip sales. Geez!

I'm sure that radio telescope sites are carefully chosen, and, if possible, surrounded by hills, and maybe totally isolated. My point is that it should NOT be necessary to create a "noise generator" that runs AT 1420 MHz, the "sweet spot on the cosmic radio dial." Commercial interests should give THAT frequency a wide berth for the greater good in our search of the cosmos.

I really doubt that if the 1420 MHz chip frequency was moved off to one side or the other, a little ways, that their performance would NOT be affected by one iota? IMHO, any reduction in "background" noise coming from earth-based sources may be ALL that is needed to FIND we are not alone in the universe. Who can say?
River Song (aka Linda Latte on planet Earth)
"Happy I-Phone girl on the GO GO GO"
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Message 1789779 - Posted: 23 May 2016, 14:43:46 UTC - in response to Message 1789767.  
Last modified: 23 May 2016, 14:44:31 UTC

If it were up to me I would be concentrating our exo-planet search on the Proxima Centauri group. I would also send a beamed message in that direction and also listen full time --perhaps with a new space-based, radio telescope.
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Message 1789780 - Posted: 23 May 2016, 14:52:06 UTC - in response to Message 1789779.  

Good idea, kind Sir! :)

Stay here on Earth. It's the only planet with DARK CHOCOLATE !!
River Song (aka Linda Latte on planet Earth)
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Message 1789802 - Posted: 23 May 2016, 16:29:03 UTC - in response to Message 1789768.  

Monday May 23 2016, 6:57 AM

It is a SAD thing that NOTHING is "holy" in our society because of commercialism; i.e. the need to make more and more $$ at the expense of anything else. In respect of the lifes work and memory of Carl Sagan and others behind SETI their work is more important, IMO, than computer chip sales. Geez!

I'm sure that radio telescope sites are carefully chosen, and, if possible, surrounded by hills, and maybe totally isolated. My point is that it should NOT be necessary to create a "noise generator" that runs AT 1420 MHz, the "sweet spot on the cosmic radio dial." Commercial interests should give THAT frequency a wide berth for the greater good in our search of the cosmos.

I really doubt that if the 1420 MHz chip frequency was moved off to one side or the other, a little ways, that their performance would NOT be affected by one iota? IMHO, any reduction in "background" noise coming from earth-based sources may be ALL that is needed to FIND we are not alone in the universe. Who can say?

Well, your idea won't work. Square waves. That is the problem. They generate radio noise over hundreds of MHz wide. That is the reason they must remove the aircraft radar from the Arecibo data.

Shielding is a much better idea; and it is required. Keep the radio noise inside the case. Works well, except for the dolts who won't put the covers on the case.

After all you wouldn't want to be near a microwave oven operating with the door open.
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Message 1789809 - Posted: 23 May 2016, 17:11:31 UTC - in response to Message 1789802.  

"Well, your idea won't work. Square waves. That is the problem. They generate radio noise over hundreds of MHz wide. That is the reason they must remove the aircraft radar from the Arecibo data.

Shielding is a much better idea; and it is required. Keep the radio noise inside the case. Works well, except for the dolts who won't put the covers on the case.

After all you wouldn't want to be near a microwave oven operating with the door open."


All are good points.. Yes, square waves are VERY broadband, and need to be confined inside a good shield. No, even if you COULD switch on a microwave oven with the door open, you would not like what could happen, and is why "screen" on its front door has the "holes" in it "sized" as they are.

Thank you for your thoughts!
River Song (aka Linda Latte on planet Earth)
"Happy I-Phone girl on the GO GO GO"
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Message boards : SETI@home Science : SETI E.T. Search Radio Interference ??


 
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