Ch 1 - P 1 - Terminology Flashcards
Amplitude
The maximum absolute value reached by a voltage or current waveform.
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Amplitude Modulation (AM)
The modulation in which the amplitude of a carrier wave is varied in accordance with some characteristic of the modulating signal.
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Analog Signal
A signal in the form of a wave that uses continuous variations of a physical characteristic over time (e.g., voltage amplitude, frequency) to transmit information.
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Attenuation
The ratio in decibels of the output power (or voltage) to the input power (or voltage) when the load and source impedance are matched to the characteristic impedance of the cable.
TDMM: Page 1-53
ATM
Asynchronous Transfer Mode - A high-speed packet switching protocol that uses fixed-length (53-byte) packets organized into cells to carry all types of traffic (e.g., voice, data, still image, audio/video). Fixed length cells allow cell processing to occur in the hardware, thereby reducing transit delays. ATM is designed to take advantage of high-speed transmission media, such as E3, synchronous optical network (SONET), and T3. TDMM Page G-13
AWG
American Wire Gauge - A system used to specify wire size. The greater the wire diameter the smaller the AWG value.
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Bandwidth
A range of frequencies available for signaling expressed in hertz (Hz). It is used to denote the potential information handling capacity of the medium, device, or system.
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Broadband Cable
Composite baseband video and audio signals that are amplitude and frequency modulated, respectively, with an RF carrier in accordance with the video and audio information that need to be conveyed (e.g., CATV).
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CO
Central Office - A common carrier switching center office (also called public exchange) that is conveniently located in areas to service subscriber homes and businesses. It provides telephony service (lines) that are connected on a local loop. The CO contains switching equipment that can switch calls locally or to long-distance carrier telephone offices.
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Codec
A device that converts speech to a digital signal and its subsequent decoding to speech.
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Cross Talk
The signal interference between cable pairs, which may be caused by a pair picking up unwanted signals from either adjacent pairs of conductors or nearby cables.
TDMM: Page 1-54
Decibel
A logarithmic unit for measuring the relative voltage, current, or power of a signal. One tenth of a bel.
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Delay Skew
The difference in propagation delay between any pairs within the same cable sheath.
TDMM: Page 1-55
Digital Signal
Information used by digital devices in the form of a sequence of discrete pulses (e.g., a binary signal with two values used to transmit the two states [0, 1]).
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Dispersion
- The loss of signal resulting from the scattering of light pulses as the are transmitted through a medium.
- The widening or spreading out of a the modes in a light pulse as it progresses along an optical fiber.
- The characteristics of the sound coverage field of a speaker.
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EMI
Electromagnetic Interference
Stray electrical energy radiated from electronic equipment and electronics systems (including cabling).
TDMM: Page 1-10
Frequency
The number of cycles that a periodic signal completes in a given time. If the unit of time is a one second, the frequency is stated in hertz (Hz). One Hz is equal to one cycle per second.
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IP
Internet Protocol - The Open Systems Interconnection (OSI) Reference Model Layer 3 (network layer) protocol most commonly used for internet working. Required for communications over the internet.
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ISDN
Integrated Services Digital Network - A digital communications facility designed to provide transparent end-to-end transmission of voice, data, audio/video and still images across the public switched telephone (PSTN). Different versions and configurations exist regionally and internationally.
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NVP
Nominal Velocity of Propagation - The coefficient used to determine the speed of transmission along a cable relative to the speed of light in a vacuum, typically expressed as a percentage. Also called phase velocity and velocity of propagation.
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PCM
Pulse Code Modulation - A technique for representing an analog signal as a string of bits. The analog signal is converted to a bit string by periodically sampling the amplitude of the analog signal and representing each sample as a binary number.
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Phase
- The relationship in time between two waveforms of the same frequency.
- The relationship in time between two parameters of a single waveform (e.g., voltage and current).
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PoE
Power over Ethernet - A network subsystem that offers the ability for the LAN switching infrastructure to provide power over balanced twisted-pair cabling to an endpoint device (e.g., access point [AP], camera, telephone set).
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Propagation Delay
The time required for a signal to travel from one end of the transmission path to the other end. (TIA)
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