Mind Boggling.... Earth's radio bubble
Stephen Arbogast
Marko Cebokli
Some movies depict aliens watching TV from Earth. Analog TV has about 5MHz of bandwidth, and needs about 20dB of signal to noise, to see a very noisy picture. Once I calculated, that they would need a planet sized antenna, to watch it at the nearest star, if the 2.7K cosmic background would be the only noise limiting their sensitivity. A clean morse code would be orders of magnitude easier, but early morse code transmissions were noise-like, using spark transmitters. Also, these were at very low frequencies, not likely to penetrate the Earth's ionosphere.
Just from the viewpoint of signal strength, our planetary radar signals would be the easiest to receive, but they are radiated with a very narrow beam, covering less than a millionth of the sky at any time.
Marko Cebokli
28.12.2025 00:28, je 'Stephen Arbogast' via Society of Amateur Radio Astronomers napisal
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