Abbreviation for nano. One billionth or 10-9.
Abbreviation for Newtons. Measure of force
generally used to specify
fiber optic cable
Abbreviation for nanoamp. One billionth of an Amp or 10-9
NA: See numerical aperture.
Abbreviation for National Association of Broadcasters. A trade association that promotes
and protects the interests of radio and television broadcasters before
Congress, federal agencies and the Courts.
| NA Mismatch
The loss of power at a joint that occurs when the transmitting half has
a numerical aperture greater than the NA of the receiving half. The loss
occurs when coupling light from a source
from fiber to fiber, or from fiber to detector.
National Electric Code®
A standard governing the use of electrical wire, cable
and fixtures installed in buildings; developed by the American National
Standards Institute (ANSI), sponsored by the National Fire Protection
Association (NFPA), identified by the description ANSI/NFPA 70-1990.
Abbreviation for National Cable Television
Association. The major trade association for the cable television
non dispersion-shifted fiber.
| Near-end Crosstalk
(NEXT, RN): The optical power reflected
from one or more input ports, back to another input port. Also known as
| Near Infrared:
part of the infrared near the visible spectrum, typically 700 nm to 1500
nm or 2000 nm; it is not rigidly defined.
Abbreviation for National Electrical Manufacturers Association. Organization
responsible for the standardization of electrical equipment, enabling
consumers to select from a range of safe, effective, and compatible
noise equivalent power.
1) An interconnection of three or more
communicating entities and (usually) one or more nodes (illustrated). 2)
A combination of
electronic components that serves a given purpose.
Network Topology: The specific physical, i.e.,
real, logical, or virtual, arrangement of the elements of a network.
Common network topologies include a bus (or linear) topology, a ring
topology, and a hybrid topology, which can be a combination of any two
or more network topologies. Illustrated to the right are four common
NF: See noise figure.
Abbreviation for National Fire Protection Association. Publisher of the
National Electrical Code®, and 300 other codes and standards through a
full, open-consensus process.
Abbreviation for nanometer. One billionth of a meter or 10-9
1) A terminal of any branch in network topology or an interconnection
common to two or more branches in a network. 2) One of the switches
forming the network backbone in a switch network. 3) A point in a
standing or stationary wave at which the amplitude is a minimum.
1) An undesired
disturbance within the frequency band of interest; the summation of
unwanted or disturbing energy introduced into a communications system
from man-made and natural sources. 2) A disturbance that affects a
signal and that may distort the information carried by the signal. 3)
Random variations of one or more characteristics of any entity such as
voltage, current, or data.
Noise Equivalent Power
The noise of optical
or of an entire transmission system, is often expressed in terms of
noise equivalent optical power.
Noise Figure (NF):
The ratio of the output
to the input signal-to-noise ratio for a given element in a transmission
system. Used for optical and electrical components.
Non Dispersion-shifted Fiber (NDSF):
The most popular type of
deployed. It is designed to have a
near 1310 nm.
The deviation from linearity
in an electronic circuit, an electro-optic device or a fiber
that generates undesired components in a signal. Examples of fiber
nonlinearities include SBS,
Non Zero-dispersion-shifted Fiber (NZ-DSF):
dispersion-shifted single-mode fiber
that has the
near the 1550 nm window, but outside the window actually used to
transmit signals. This strategy maximizes bandwidth while minimizing
Abbreviation for non-return to zero. A common
means of encoding data that has two states termed “zero” and “one” and
no neutral or rest position.
Abbreviation for nanosecond. One billionth of a
second or 10-9 seconds.
1) Abbreviation for National Television Systems Committee. The
organization which formulated the NTSC system. 2) Standard used in the
U.S. that delivers 525 lines at 60 frames per second.
The light-gathering ability of a fiber;
the maximum angle to the fiber axis
at which light will be accepted and propagated through the fiber. NA =
a, where a is the
NA also describes the angular spread of light from a central axis, as in
exiting a fiber, emitting from a
or entering a detector.
Abbreviation for nanowatt. One billionth of a Watt or 10-9
| Nyquist Frequency:
The lowest sampling frequency that can be used for
of a signal without resulting in significant aliasing. Normally, this
frequency is twice the rate of the highest frequency contained in the
signal being sampled. Also called Nyquist rate.
See non zero-dispersion-shifted fiber.