Full width at half maximumIn a distribution, full width at half maximum (FWHM) is the difference between the two values of the independent variable at which the dependent variable is equal to half of its maximum value. In other words, it is the width of a spectrum curve measured between those points on the y-axis which are half the maximum amplitude. Half width at half maximum (HWHM) is half of the FWHM if the function is symmetric.
Bandwidth (signal processing)Bandwidth is the difference between the upper and lower frequencies in a continuous band of frequencies. It is typically measured in unit of hertz (symbol Hz). It may refer more specifically to two subcategories: Passband bandwidth is the difference between the upper and lower cutoff frequencies of, for example, a band-pass filter, a communication channel, or a signal spectrum.
Spectral bandSpectral bands are regions of a given spectrum, having a specific range of wavelengths or frequencies. Most often, it refers to electromagnetic bands, regions of the electromagnetic spectrum. More generally, spectral bands may also be defined in the spectra of other types of signals, e.g., noise spectrum. A frequency band is an interval in the frequency domain, limited by a lower frequency and an upper frequency.
Fiber-optic communicationTransmitting information over optical fiberAn optical fiber patching cabinet.
TelecommunicationsTelecommunication, often used in its plural form or abbreviated as telecom, is the transmission of information over a distance using electrical or electronic means, typically through cables, radio waves, or other communication technologies. These means of transmission may be divided into communication channels for multiplexing, allowing for a single medium to transmit several concurrent communication sessions.
DecibelThe decibel (symbol: dB) is a relative unit of measurement equal to one tenth of a bel (B). It expresses the ratio of two values of a power or root-power quantity on a logarithmic scale. Two signals whose levels differ by one decibel have a power ratio of 10 (approximately 1.26) or root-power ratio of 10 (approximately 1.12). The strict original usage above only expresses a relative change.
Root mean squareIn mathematics, the root mean square (abbrev. RMS, rms or rms) of a set of values is the square root of the set's mean square. Given a set xi{\displaystyle x_{i}}, its RMS is denoted as either xRMS{\displaystyle x_{\mathrm {RMS} }} or RMSx{\displaystyle \mathrm {RMS} _{x}}. The RMS is also known as the quadratic mean (denoted M2{\displaystyle M_{2}}), a special case of the generalized mean.
Pure toneIn psychoacoustics and signal processing, a pure tone is a sound or other signal with a sinusoidalwaveform; that is, a sinewave of constant frequency, phase-shift, and amplitude. A pure tone has the property – unique among real-valued wave shapes – that its wave shape is unchanged by linear time-invariant systems; that is, only the phase and amplitude change between such a system's pure-tone input and its output.*As an Amazon Associate I earn from qualifying purchases.