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From early in the 20th century, the radio frequency of 500 kilohertz (500 kHz) was an international calling and distress frequency for Morse code maritime communication. . For much of its early history, this frequency was referred to by its equivalent wavelength, 600 meters, or, using the earlier frequency unit name, 500 kilocycles (per second) or 500 k
The hertz is defined as one per second for periodic events. The International Committee for Weights and Measures defined the second as "the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom" [3] [4] and then adds: "It follows that the hyperfine splitting in the ground state of the ...
8 kHz: ISDN sampling rate 10 4: 10 kHz 14 kHz: Acoustic – the typical upper limit of adult human hearing 17.4 kHz: Acoustic – a frequency known as the Mosquito, which is generally only audible to those under the age of 24. 25.1 kHz Acoustic – G 10, the highest pitch sung by Georgia Brown, who has a vocal range of 8 octaves. 44.1 kHz
The first fully mechanical analog computer, the Z1, operated at 1 Hz (cycle per second) clock frequency and the first electromechanical general purpose computer, the Z3, operated at a frequency of about 5–10 Hz. The first electronic general purpose computer, the ENIAC, used a 100 kHz clock in its cycling unit. As each instruction took 20 ...
Doppler signals fall between 1.5 kHz, and 15 kHz, which is audible, so audio signals from medium-PRF radar systems can be used for passive target classification. For example, an L band radar system using a PRF of 10 kHz with a duty cycle of 3.3% can identify true range to a distance of 450 km (30 * C / 10,000 km/s).
The cycle per second is a once-common English name for the unit of frequency now known as the hertz (Hz). Cycles per second may be denoted by c.p.s., c/s, or, ambiguously, just "cycles" (Cyc., Cy., C, or c). The term comes from repetitive phenomena such as sound waves having a frequency measurable as a number of oscillations, or cycles, per ...
Even in dispersive media, the frequency f of a sinusoidal wave is equal to the phase velocity v of the wave divided by the wavelength λ of the wave: =. In the special case of electromagnetic waves in vacuum , then v = c , where c is the speed of light in vacuum, and this expression becomes f = c λ . {\displaystyle f={\frac {c}{\lambda }}.}
A typical choice of characteristic frequency is the sampling rate that is used to create the digital signal from a continuous one.The normalized quantity, ′ =, has the unit cycle per sample regardless of whether the original signal is a function of time or distance.