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1. The rate of change of the total phase shift with respect to angular frequency, d θ/d ω, through a device or transmission medium, where θ is the total phase shift, and ω is the angular frequency equal to 2πf , where f is the frequency.

2. In an optical fiber, the transit time required for optical power, traveling at a given mode's group velocity, to travel a given distance.

Note: For optical fiber dispersion measurement purposes, the quantity of interest is group delay per unit length, which is the reciprocal of the group velocity of a particular mode. The measured group delay of a signal through an optical fiber exhibits a wavelengthThe wavelength is the distance between repeating units of a wave pattern. It is commonly designated by the greek letter lambda (λ). In a sine wave, the wavelength is the distance between peaks: The x axis represents distance, and I would be some va dependence due to the various dispersion mechanisms present in the fiber.

Source: from Federal Standard 1037CFederal Standard 1037C entitled Telecommunications: Glossary of Telecommunication Terms is a U. Federal Standard, issued by the General Services Administration pursuant to the Federal Property and Administrative Services Act of 1949, as amended. This docu

It is often desirable that group delay be constant across all frequencies; otherwise there is temporal smearing of the signal. Because group delay is d θ/d ω, as defined in (1), it therefore follows that a constant group delay can be achieved if the transfer functionA transfer function is a mathematical representation of the relation between the input and output of a linear time-invariant system. It is mainly used in linear system theory, signal processing, communications theory, and control theory. Signal processing of the device or medium has a linearThe word linear comes from the latin word linearis which means created by lines''. In mathematics, a linear function f ''x is one which satisfies the following two properties (but see below for a slightly different usage of the term): Additivity: f ''x + phase response (i.e., θ = Kω where K is a constant).

Thresholds of audibility according to Blauert and Laws:

1 See also

• Audio system measurementsThe designer of a system for sound reproduction needs to be able to measure the system's performance in a number of areas. While this is not a measure of quality but of quantity, it is a fact that certain quantifiable measurements must be of a certain ord

2 External links

• Discussion of Group Delay in Loudspeakers