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  2. R-S-T system - Wikipedia

    en.wikipedia.org/wiki/R-S-T_system

    S-Meter (ICOM IC-732 HF Transceiver) The R-S-T system is used by amateur radio operators, shortwave listeners, and other radio hobbyists to exchange information about the quality of a radio signal being received. The code is a three digit number, with one digit each for conveying an assessment of the signal's readability, strength, and tone.

  3. Extremely low frequency - Wikipedia

    en.wikipedia.org/wiki/Extremely_low_frequency

    Extremely low frequency ( ELF) is the ITU designation [1] for electromagnetic radiation ( radio waves) with frequencies from 3 to 30 Hz, and corresponding wavelengths of 100,000 to 10,000 kilometers, respectively. [2] [3] In atmospheric science, an alternative definition is usually given, from 3 Hz to 3 kHz. [4] [5] In the related magnetosphere ...

  4. Radioteletype - Wikipedia

    en.wikipedia.org/wiki/Radioteletype

    Radioteletype ( RTTY) is a telecommunications system consisting originally of two or more electromechanical teleprinters in different locations connected by radio rather than a wired link. Radioteletype evolved from earlier landline teleprinter operations that began in the mid-1800s. [1] The US Navy Department successfully tested printing ...

  5. Active noise control - Wikipedia

    en.wikipedia.org/wiki/Active_noise_control

    Noise control is an active or passive means of reducing sound emissions, often for personal comfort, environmental considerations, or legal compliance. Active noise control is sound reduction using a power source. Passive noise control is sound reduction by noise-isolating materials such as insulation, sound-absorbing tiles, or a muffler rather ...

  6. Shortwave listening - Wikipedia

    en.wikipedia.org/wiki/Shortwave_listening

    Shortwave listening, or SWLing, is the hobby of listening to shortwave radio broadcasts located on frequencies between 1700 kHz and 30 MHz (30 000 kHz). [1] Listeners range from casual users seeking international news and entertainment programming, to hobbyists immersed in the technical aspects of long-distance radio reception and sending and ...

  7. Radio wave - Wikipedia

    en.wikipedia.org/wiki/Radio_wave

    Air is thin enough that in the Earth's atmosphere radio waves travel very close to the speed of light. The wavelength is the distance from one peak (crest) of the wave's electric field to the next, and is inversely proportional to the frequency of the wave. The relation of frequency and wavelength in a radio wave traveling in vacuum or air is.

  8. Audio time stretching and pitch scaling - Wikipedia

    en.wikipedia.org/wiki/Audio_time_stretching_and...

    Time stretching is the process of changing the speed or duration of an audio signal without affecting its pitch. Pitch scaling is the opposite: the process of changing the pitch without affecting the speed. Pitch shift is pitch scaling implemented in an effects unit and intended for live performance. Pitch control is a simpler process which ...

  9. Signal strength in telecommunications - Wikipedia

    en.wikipedia.org/wiki/Signal_strength_in...

    In telecommunications, [1] particularly in radio frequency engineering, signal strength refers to the transmitter power output as received by a reference antenna at a distance from the transmitting antenna. High-powered transmissions, such as those used in broadcasting, are expressed in dB - millivolts per metre (dBmV/m).