AV Design Reference Manual - InfoComm

Glossary
Nyquist frequency The highest frequency of the analog signal being recorded and equal
to half of the sampling rate.
Nyquist theorem A theorem that states the sampling rate must be at least twice the
highest frequency of the analog signal being sampled
O
off-line uninterruptible power supply (UPS) unit A device that powers the load
directly from the utility and only provides backup power when the utility power goes
below the preset tolerances. Also called standby uninterruptible power supply unit.
Ohm’s law The mathematical relationship among electric current, resistance, and voltage.
The voltage in volts is equal to the current in amperes multiplied by the resistance in ohms.
omnidirectional microphone A microphone that picks up sound from all directions
equally, with a slight preference for the sounds coming from the direction in which they
are pointed.
online double-conversion uninterruptible power supply (UPS) A conventional
uninterruptible power supply unit that completely rectifies the alternating current (ac) line
from ac to direct current (dc) and uses this dc to both charge the battery and power a dc/
ac inverter.
Open Systems Interconnection (OSI) Reference Model A seven-layer architecture
developed by the International Organization for Standardization that has served as a
foundation for the development of many standards for network systems communications.
The seven layers are physical, data link, network, transport, session, presentation, and
application.
optical fiber cable Cable made up of one or more strands of glass consisting of a central
core and outer cladding (optical fibers), strength members, and an outer jacket.
overcurrent protection device (OCPD) Thermal or thermal-magnetic devices such as
circuit breakers or fuses. An individual circuit might provide power to all of the lights in a
room or several electrical convenience outlets, but the total power consumed on the circuit
cannot exceed the current limiting device’s rating.
P
panelboard A single panel (or group of panel units designed for assembly to form a single
panel) that includes buses and automatic overcurrent devices (circuit breakers or fuses)
with or without switches for the control of light, heat, or power circuits.
parametric equalizer (EQ) An equalizer with two or three knobs that allow users the
control over various frequency aspects of the signal. One control allows selecting a
specific frequency. Another control determines how much boost or reduction is applied to
that frequency
AVDRM, 1st edition G-18 © 2006 BICSI ® /InfoComm International ®