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High-resolution audio (high-definition audio or HD audio) is a term for audio files with greater than 44.1 kHz sample rate or higher than 16-bit audio bit depth. It commonly refers to 96 or 192 kHz sample rates. However, 44.1 kHz/24-bit, 48 kHz/24-bit and 88.2 kHz/24-bit recordings also exist that are labeled HD Audio.
Short title: Very-low-frequency radio propagation in the ionosphere: Author: Swift, Daniel W. Software used: Adobe Acrobat 9.0: Conversion program: Adobe Acrobat 9.13 Paper Capture Plug-in
Relationship of the atmosphere and ionosphere. The ionosphere (/ aɪ ˈ ɒ n ə ˌ s f ɪər /) [1] [2] is the ionized part of the upper atmosphere of Earth, from about 48 km (30 mi) to 965 km (600 mi) above sea level, [3] a region that includes the thermosphere and parts of the mesosphere and exosphere. The ionosphere is ionized by solar ...
ELF and VLF waves propagate long distances by an Earth–ionosphere waveguide mechanism. [5] [18] The Earth is surrounded by a layer of charged particles (ions and electrons) in the atmosphere at an altitude of about 60 km (37 mi) at the bottom of the ionosphere, called the D layer, which reflects ELF waves.
The ionosphere is a region of the atmosphere from about 60 to 500 km (37 to 311 mi) that contains layers of charged particles which can refract a radio wave back toward the Earth. A radio wave directed at an angle into the sky can be reflected back to Earth beyond the horizon by these layers, allowing long-distance radio transmission.
The ionosphere is an ideal place to look for the telltale signs of this particular form of dark matter, the scientists explain, because we already spend a lot of time and resources doing studies ...
The conductive ionosphere and the conductive Earth form a horizontal "duct" a few VLF wavelengths high, which acts as a waveguide confining the waves so they don't escape into space. The waves travel in a zig-zag path around the Earth, reflected alternately by the Earth and the ionosphere, in transverse magnetic (TM) mode.
The ionosphere is a layer of partially ionized gases high above the majority of the Earth's atmosphere; these gases are ionized by cosmic rays originating on the sun. When radio waves travel into this zone, which commences about 80 kilometers above the earth, they experience diffraction in a manner similar to the visible light phenomenon described above. [1]