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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 .
A return period, also known as a recurrence interval or repeat interval, is an average time or an estimated average time between events such as earthquakes, floods, [1] landslides, [2] or river discharge flows to occur. It is a statistical measurement typically based on historic data over an extended period, and is used usually for risk analysis.
The cumulative frequency is the total of the absolute frequencies of all events at or below a certain point in an ordered list of events. [ 1 ] : 17–19 The relative frequency (or empirical probability ) of an event is the absolute frequency normalized by the total number of events:
Most frequency counters work by using a counter, which accumulates the number of events occurring within a specific period of time.After a preset period known as the gate time (1 second, for example), the value in the counter is transferred to a display, and the counter is reset to zero.
The image sampling frequency is the repetition rate of the sensor integration period. Since the integration period may be significantly shorter than the time between repetitions, the sampling frequency can be different from the inverse of the sample time: 50 Hz – PAL video; 60 / 1.001 Hz ~= 59.94 Hz – NTSC video
Frequency analysis [2] is the analysis of how often, or how frequently, an observed phenomenon occurs in a certain range. Frequency analysis applies to a record of length N of observed data X 1, X 2, X 3. . . X N on a variable phenomenon X. The record may be time-dependent (e.g. rainfall measured in one spot) or space-dependent (e.g. crop ...
An intensity-duration-frequency curve (IDF curve) is a mathematical function that relates the intensity of an event (e.g. rainfall) with its duration and frequency of occurrence. [1] Frequency is the inverse of the probability of occurrence. These curves are commonly used in hydrology for flood forecasting and civil engineering for urban ...
Figure 1 shows the waveform of an audio file "" with 44100 Hz sampling frequency. Figure 2 shows the time-frequency plot of the short-time Fourier transform (in particular, Gabor transform) results of the audio file. In this plot, horizontal lines with frequencies not greater than 230 Hz represent the fundamental frequencies while horizontal ...