linkedin post 2021-01-15 04:56:55

linkedin post 2021-01-15 04:56:55

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UHF SIGNALS. “The telecommunication systems increasingly utilize ultra-high-frequency (UHF) bands to transmit signal to satellites to be relayed to other locations. Also this frequency range is vulnerable to the auroral currents in the ionosphere, and can be degraded or even completely lost during times of high activity.” https://link.springer.com/article/10.12942/lrsp-2007-1 View in LinkedIn
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linkedin post 2021-01-17 06:53:48

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HAYSTACK. “This "needle in a haystack" metaphor is especially appropriate in a SETI context because it emphasizes the vastness of the space to be searched, and it nicely captures how we seek an obvious product of intelligence and technology amidst a much larger set of purely natural products.” https://lnkd.in/dKzsrBv View in LinkedIn
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linkedin post 2021-01-15 04:55:37

linkedin post 2021-01-15 04:55:37

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HF SIGNALS. “High frequency (HF) radio wave communications are most affected, as they utilize reflection from the ionosphere to carry the signal to distances beyond the local horizon. At times of high auroral activity, the signal can be even completely absorbed making the HF radio propagation impossible.” https://link.springer.com/article/10.12942/lrsp-2007-1 View in LinkedIn
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linkedin post 2021-01-16 05:11:47

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FARMER TALK. Working on a Herefordshire mixed sheep farm for a spell at 18, the farmer mysteriously advised me as we entered a field with two tractors to start ploughing: “go up the smooth and down the rough.” After a while, it made sense. Later in life, I discover on sanding wood a similar common truth which made me think of the farmer: sand with the grain, not across it. Common sense is not always common. View in LinkedIn
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linkedin post 2021-01-16 05:05:20

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DIMENSIONALITY. “Tarter (2006, 2010) described the search space as a "nine-dimensional haystack" in terms of three spatial dimensions, one temporal dimension (when the signal is "on"), two polarization dimensions, central frequency, sensitivity, and modulation.” https://lnkd.in/dKzsrBv View in LinkedIn
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linkedin post 2021-01-16 05:03:29

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RATIONALIZED PARAMETERS. “Similarly, Papagiannis (1985) described the "SETI search space" of two NASA SETI search programs for narrowband transmission in terms of the frequencies searched, fraction of sky surveyed, and instrument sensitivity. He distinguished between the Targeted search that parameterized the haystack in terms of the number of targets surveyed (discrete sources at good sensitivity) and a Sky Survey program parameterized in terms of sky coverage (i.e., a shallower search for any transmitters in the beam).” https://lnkd.in/dKzsrBv View in LinkedIn
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linkedin post 2021-01-16 05:01:39

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COSMIC HAYSTACK. “They then "compressed" the three dimensions of polarization, frequency of transmission, and signal modulation by considering only obvious, continuous signals searched for with receivers sensitive to orthogonal polarizations. Next, they compressed the three spatial dimensions into a single axis in terms of the number of targets or beams surveyed. They then graphically illustrated a three-dimensional "Cosmic Haystack" through which various SETI programs had hunted, looking for "needles." https://lnkd.in/dKzsrBv View in LinkedIn
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linkedin post 2021-01-16 04:59:22

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MANY TYPES OF SIGNALS. “Unlike solar neutrinos, however, the potential number of technosignatures is quite large and difficult to parameterize. In one early visualization of the search space for radio communication SETI, Wolfe et al. (1981) identified several relevant parameters: polarization, repetition rate of transmission, signal modulation, three spatial dimensions, central transmission frequency, and receiver sensitivity. “ https://lnkd.in/dKzsrBv View in LinkedIn
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