A disturbance often measured in multimode fiber-optic transmissions that are fed by diode lasers. The higher quality the laser light feeding the fiber, the less modal noise will be measured.
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A single wave traveling in an optical fiber or in a light path through a fiber. Light has modes in optical-fiber cable. A high-order mode is a path that results in numerous reflections off the core/cladding interface. A loworder mode results in fewer reflections. A zero-order mode is a path that goes through the fiber without reflecting off the interface at all. In a single-mode fiber, only one mode (the fundamental mode) can propagate through the fiber. Multimode fiber has several hundred modes that differ in field pattern and propagation velocity. The number of modes in an optical fiber is determined by the diameter of the core, the wavelength of the light passing through it, and the refractive indexes of the core and cladding. The number of modes increases as the core diameter increases, the wavelength decreases, or the difference between refractive indexes increases.
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|Mode field diameter (MFD)||
The actual diameter of the light beam traveling through the core and part of the cladding and across the endface in a single-mode fiber-optic cable. Since the mode field diameter is usually greater than the core diameter,
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A device that can select, attenuate, or reject a specific mode. Mode filters are used to remove high-order modes from a fiber and thereby simulate EMD. See also mandrel wrap.
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A device that removes high-order modes in a multimode fiber to give standard measurement conditions.
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A device that implements modulator-demodulator functions to convert between digital data and analog signals.
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|Modified modular jack (MMJ)||
A six-wire modular jack used by the DEC wiring system. The MMJ has a locking tab that is shifted to the righthand side.
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Equipment is said to be modular when it is made of plugin units that can be added together to make the system larger, improve the capabilities, or expand its size. Faceplates made for use with structured cabling systems are often modular and permit the use of multiple types of telecommunications outlets or modular jacks such as RJ-45, coaxial, audio, or fiber.
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A female telecommunications interface connector. Modular jacks are typically mounted in a fixed location and may have four, six, or eight contact positions, though most typical standards-based cabling systems will have an eight-position jack. Not all positions need be equipped with contacts. The modular jack may be keyed or unkeyed so as to permit only certain types of plugs to be inserted into the jack.
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(1) To convert data into a signal that can be transmitted by a carrier. (2) To control.
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(1) Coding of information onto the carrier frequency. Types of modulation include amplitude modulation (AM), frequency modulation (FM), and phase modulation (PM). (2) When light is emitted by a medium, it is coherent, meaning that it is in a fixed-phase relationship within fixed points of the light wave. The light is used because it is a continuous, or sinusoidal, wave (a white or blank form) upon which a signal can be superimposed by modulation of that form. The modulation is a variation imposed upon this white form, a variation of amplitude, frequency, or phase of the light. There are two basic forms of this modulation: one by an analog form, another by a digital signal. This signal is created in the form of the
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Light having only one color, or more accurately only one wavelength.
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Multiple-Operator Radio Access Network configuration
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|Motion Pictures Experts Group (MPEG)||
A standards group operating under the ISO that develops standards for digital video and audio compression.
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