by neufer » Sun Jul 12, 2009 10:28 pm
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http://www.cplire.ru/html/ra&sr/irm/CosmicCall-2003/index.html wrote:
Synthesis and Transmission of Cosmic Call 2003
Interstellar Radio Message
The team used the National Space Agency of Ukraine's Evpatoria Planetary Radar (EPR) in Crimea. The broadcast was a follow-on to Team Encounter's Cosmic Call 1999. The transmitting system of the EPR has not been changed since 1999. Its main characteristics are as follows:
the central frequency is 5.01 GHz, and the effective area of the transmitting antenna is about 2500 square meters.
The work is conducted from a highly stable hydrogen generator in a mode of continuous coherent radiation with average capacity up to 150 kW. The digital information is transmitted using carrying frequency manipulation with a deviation of 48 kHz: The nominal shift of +24 kHz corresponds to the symbol "1" and the shift of -24 kHz corresponds to the symbol "0." We assume the technology THERE is only ten years more advanced than our own. For a distance of 50 light-years, corresponding calculations give the value of 400 bits per second as the appropriate transmission rate for broadcast of Cosmic Call 2003's scientific messages. Three basic messages of the scientific message - the Interstellar Rosetta Stone, the 1974 Arecibo Message, and the Bilingual Image Glossary - were transmitted thrice to avoid message fading. The Interstellar Rosetta Stone (ISR) is a message created by Canadian scientists Yvan Dutil and Stephane Dumás, authors of a similar Scientific Message in Cosmic Call 1999. The size of the ISR is 263906 bits with 127 symbols in each of 2078 lines. [Their] message of 1999 consisted of
23 pages where each page was 127 X 127 binary elements.>>
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http://www.setileague.org/general/waterhol.htm wrote:
What Is the Water-Hole?
<<The electromagnetic spectrum, as viewed from Earth, is a noisy place. Low frequencies are plagued by galactic noise, primarily due to synchrotron radiation (charged particles spiraling through our Sun's and our planet's magnetic fields). High frequencies are subject to quantum-effect emissions, and the whole continuum experiences a 3 Kelvin background radiation level from the residual radiation of the Big Bang. These natural radiation sources limit our ability to detect artificial emissions. In addition, the Earth's own ocean of air generates spectral absorption and emission lines which draw a further curtain across our sky. Fortunately, there are a few relatively clear windows on the cosmos. Our eyes evolved to operate in one such window, the optical spectrum. It is this window which first allowed us to observe the stars and planets.
Another clear spot is in the microwave region, between about 1 and 10 GHz.
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[Note: Galaxies are "radio quiet" at frequencies above 2 GHZ but
earthbound radio telescopes must avoid the broad tropospheric 22 GHZ water vapor line.]
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Within this so-called Microwave Window, photons (the substance of electromagnetic communication) travel relatively unimpeded through the interstellar medium, at the speed of light. This is, as far as we know, the fastest possible speed, making photons the fastest spaceships known to man. Thus the Microwave Window, where natural noise is at a minimum, is a favored region for conducting radio astronomy research, including SETI.
Toward the bottom of the microwave window, radiation from the precession of interstellar hydrogen is clearly heard in our receivers at a frequency of 1420.40575 MHz (corresponding to a wavelength around 21 cm). The Hydrogen Line, first detected by Ewen and Purcell at Harvard University in 1951, provided us with our first direct evidence that space is anything but an empty void -- it is a veritable chemistry set. We hypothesize that any civilization in the cosmos which possesses radio astronomy knows about the Hydrogen Line. Since there is roughly one hydrogen atom per cubic centimeter of space, the combined voices of countless hydrogen atoms produce a raucous chorus. The very first SETI studies were conducted near the Hydrogen Line, and today it still looks like a logical place to seek deliberate beacons from beyond.
Just a little way up the spectrum, near 1660 MHz (a wavelength of 18 cm), a team of scientists at MIT Lincoln Labs detected in the 1960s a cluster of radiation lines from interstellar hydroxyl ions (OH). Like the Hydrogen Line, the Hydroxyl Lines occur near the very quietest part of the radio spectrum. They too should be known to other civilizations which have studied the cosmos at radio frequencies.
The chemist looks at H and OH and recognizes them as the disassociation products of water, the solvent essential to the very existence of life as we know it. During the landmark Cyclops study of 1971, Dr. Bernard M. Oliver, then vice-president of engineering for Hewlett-Packard Company (and later the chief of the NASA SETI program) hypothesized that the Hydrogen and Hydroxyl lines constituted obvious signposts to a natural interstellar communications band, one which would likely occur to other water-based lifeforms who had some knowledge of the radio sky. Since the H and OH lines are visible from anywhere in the cosmos, in the quietest part of the spectrum, they are markers which are by no means geocentric.
It was Barney Oliver who dubbed the spectral region between H and OH the Cosmic Water-Hole. "Where shall we meet our neighbors?" he asked. "At the water-hole, where species have always gathered."
Although other regions of the spectrum hold much promise, The SETI League and other organizations concentrate a part of their resources on the Water-Hole, in hopes that there we might detect signs of other life.>>
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[quote=" http://www.cplire.ru/html/ra&sr/irm/CosmicCall-2003/index.html"]
Synthesis and Transmission of Cosmic Call 2003
Interstellar Radio Message
The team used the National Space Agency of Ukraine's Evpatoria Planetary Radar (EPR) in Crimea. The broadcast was a follow-on to Team Encounter's Cosmic Call 1999. The transmitting system of the EPR has not been changed since 1999. Its main characteristics are as follows:
[b]the central frequency is 5.01 GHz[/b], and the effective area of the transmitting antenna is about 2500 square meters.
The work is conducted from a highly stable hydrogen generator in a mode of continuous coherent radiation with average capacity up to 150 kW. The digital information is transmitted using carrying frequency manipulation with a deviation of 48 kHz: The nominal shift of +24 kHz corresponds to the symbol "1" and the shift of -24 kHz corresponds to the symbol "0." We assume the technology THERE is only ten years more advanced than our own. For a distance of 50 light-years, corresponding calculations give the value of 400 bits per second as the appropriate transmission rate for broadcast of Cosmic Call 2003's scientific messages. Three basic messages of the scientific message - the Interstellar Rosetta Stone, the 1974 Arecibo Message, and the Bilingual Image Glossary - were transmitted thrice to avoid message fading. The Interstellar Rosetta Stone (ISR) is a message created by Canadian scientists Yvan Dutil and Stephane Dumás, authors of a similar Scientific Message in Cosmic Call 1999. The size of the ISR is 263906 bits with 127 symbols in each of 2078 lines. [Their] message of 1999 consisted of [b]23 pages where each page was 127 X 127 binary elements[/b].>>[/quote]
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[quote=" http://www.setileague.org/general/waterhol.htm"]
What Is the Water-Hole?
<<The electromagnetic spectrum, as viewed from Earth, is a noisy place. Low frequencies are plagued by galactic noise, primarily due to synchrotron radiation (charged particles spiraling through our Sun's and our planet's magnetic fields). High frequencies are subject to quantum-effect emissions, and the whole continuum experiences a 3 Kelvin background radiation level from the residual radiation of the Big Bang. These natural radiation sources limit our ability to detect artificial emissions. In addition, the Earth's own ocean of air generates spectral absorption and emission lines which draw a further curtain across our sky. Fortunately, there are a few relatively clear windows on the cosmos. Our eyes evolved to operate in one such window, the optical spectrum. It is this window which first allowed us to observe the stars and planets. [b]Another clear spot is in the microwave region, between about 1 and 10 GHz.[/b]
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[list][b]Water-Hole spectrum[/b][/list]
[img]http://www.setileague.org/photos/miscpix/waterhol.gif[/img]
[b][Note: Galaxies are "radio quiet" at frequencies above 2 GHZ but
[color=#FF0000]earthbound radio telescopes[/color] must avoid the broad tropospheric 22 GHZ water vapor line.][/b]
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Within this so-called Microwave Window, photons (the substance of electromagnetic communication) travel relatively unimpeded through the interstellar medium, at the speed of light. This is, as far as we know, the fastest possible speed, making photons the fastest spaceships known to man. Thus the Microwave Window, where natural noise is at a minimum, is a favored region for conducting radio astronomy research, including SETI.
Toward the bottom of the microwave window, radiation from the precession of interstellar hydrogen is clearly heard in our receivers at a frequency of 1420.40575 MHz (corresponding to a wavelength around 21 cm). The Hydrogen Line, first detected by Ewen and Purcell at Harvard University in 1951, provided us with our first direct evidence that space is anything but an empty void -- it is a veritable chemistry set. We hypothesize that any civilization in the cosmos which possesses radio astronomy knows about the Hydrogen Line. Since there is roughly one hydrogen atom per cubic centimeter of space, the combined voices of countless hydrogen atoms produce a raucous chorus. The very first SETI studies were conducted near the Hydrogen Line, and today it still looks like a logical place to seek deliberate beacons from beyond.
Just a little way up the spectrum, near 1660 MHz (a wavelength of 18 cm), a team of scientists at MIT Lincoln Labs detected in the 1960s a cluster of radiation lines from interstellar hydroxyl ions (OH). Like the Hydrogen Line, the Hydroxyl Lines occur near the very quietest part of the radio spectrum. They too should be known to other civilizations which have studied the cosmos at radio frequencies.
The chemist looks at H and OH and recognizes them as the disassociation products of water, the solvent essential to the very existence of life as we know it. During the landmark Cyclops study of 1971, Dr. Bernard M. Oliver, then vice-president of engineering for Hewlett-Packard Company (and later the chief of the NASA SETI program) hypothesized that the Hydrogen and Hydroxyl lines constituted obvious signposts to a natural interstellar communications band, one which would likely occur to other water-based lifeforms who had some knowledge of the radio sky. Since the H and OH lines are visible from anywhere in the cosmos, in the quietest part of the spectrum, they are markers which are by no means geocentric.
It was Barney Oliver who dubbed the spectral region between H and OH the Cosmic Water-Hole. "Where shall we meet our neighbors?" he asked. "At the water-hole, where species have always gathered."
[img]http://www.exploratorium.edu/learning_studio/news/october97/water_hole_sm2.jpg[/img][img]http://www.frederic-remington.org/Fight-For-The-Water-Hole.jpg[/img]
Although other regions of the spectrum hold much promise, The SETI League and other organizations concentrate a part of their resources on the Water-Hole, in hopes that there we might detect signs of other life.>>[/quote]
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