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  2. Frequency - Wikipedia

    en.wikipedia.org/wiki/Frequency

    The period (symbol T) is the interval of time between events, so the period is the reciprocal of the frequency: T = 1/f. [ 2 ] Frequency is an important parameter used in science and engineering to specify the rate of oscillatory and vibratory phenomena, such as mechanical vibrations, audio signals ( sound ), radio waves , and light .

  3. Wavenumber - Wikipedia

    en.wikipedia.org/wiki/Wavenumber

    For example, a wavenumber in inverse centimeters can be converted to a frequency expressed in the unit gigahertz by multiplying by 29.979 2458 cm/ns (the speed of light, in centimeters per nanosecond); [5] conversely, an electromagnetic wave at 29.9792458 GHz has a wavelength of 1 cm in free space.

  4. Discrete-time Fourier transform - Wikipedia

    en.wikipedia.org/wiki/Discrete-time_Fourier...

    The subscript / distinguishes it from the continuous Fourier transform (), and from the angular frequency form of the DTFT. The latter is obtained by defining an angular frequency variable, ω ≜ 2 π f T {\displaystyle \omega \triangleq 2\pi fT} (which has normalized units of radians/sample ), giving us a periodic function of angular ...

  5. Spatial frequency - Wikipedia

    en.wikipedia.org/wiki/Spatial_frequency

    The value of each data point in k-space is measured in the unit of 1/meter, i.e. the unit of spatial frequency. It is very common that the raw data in k-space shows features of periodic functions. The periodicity is not spatial frequency, but is temporal frequency. An MRI raw data matrix is composed of a series of phase-variable spin-echo signals.

  6. Rayleigh's quotient in vibrations analysis - Wikipedia

    en.wikipedia.org/wiki/Rayleigh's_quotient_in...

    In the previous equation it is also possible to observe that the numerator is proportional to the potential energy while the denominator depicts a measure of the kinetic energy. Moreover, the equation allow us to calculate the natural frequency only if the eigenvector (as well as any other displacement vector) u m {\displaystyle {\textbf {u ...

  7. Square wave - Wikipedia

    en.wikipedia.org/wiki/Square_wave

    The ratio of the high period to the total period of a pulse wave is called the duty cycle. A true square wave has a 50% duty cycle (equal high and low periods). Square waves are often encountered in electronics and signal processing, particularly digital electronics and digital signal processing. Its stochastic counterpart is a two-state ...

  8. Talk:Wave period - Wikipedia

    en.wikipedia.org/wiki/Talk:Wave_period

    The rest of the article is a list of formulas like "period = 1 / frequency" and "frequency = 1 / period" which are the same formula restated and can be found in the reciprocal article, talk about some SI units (Hertz and seconds), and another list of formulas like "wavelength / time = velocity" that are restated 6 times. Seems like a pointless ...

  9. Periodic function - Wikipedia

    en.wikipedia.org/wiki/Periodic_function

    Consider a real waveform consisting of superimposed frequencies, expressed in a set as ratios to a fundamental frequency, f: F = 1 ⁄ f [f 1 f 2 f 3... f N] where all non-zero elements ≥1 and at least one of the elements of the set is 1. To find the period, T, first find the least common denominator of all the elements in the set.