| n: Abbreviation for nano. One billionth or 10-9. |
| N: Abbreviation for Newtons. Measure of force generally used to
specify fiber
optic cable tensile strength. |
| nA: Abbreviation for
nanoamp. One billionth of an Amp or 10-9 Amps. |
| NA: See numerical
aperture. |
| NAB: Abbreviation for
National Association of Broadcasters.
|
http://www.nab.org/ |
| NA Mismatch
Loss: 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 to fiber,
from fiber to fiber, or from fiber to detector. |
 |
| National
Electric Code (NEC): 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. |
http://www.ansi.org/ |
| NCTA: Abbreviation for National Cable Television Association. The major
trade association for the cable television industry. |
http://www.ncta.com/ |
| NDSF: See 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 isolation
directivity. |
| Near Infrared: The part of the infrared near the visible spectrum, typically 700
nm to 1500 nm or 2000 nm; it is not rigidly defined. |
| NEMA: Abbreviation for
National Electrical Manufacturers Association.
|
http://www.nema.org/ |
| NEP: See noise equivalent
power. |
| Network: 1) An
interconnection of three or more communicating entities and (usually) one
or more nodes (illustrated). 2) A combination of passive or active 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 is a bus topology utilizing tee
couplers to connect a series of stations that listen to a single backbone
of cable. |
 |
| NF: See noise
figure. |
| NFPA: Abbreviation for
National Fire Protection Association. Publisher of the
National Electrical Code? and 300 other codes and standards through a
full, open-consensus process. |
http://www.nfpa.org/Home/index.asp |
| nm: Abbreviation for
nanometer. One billionth of a meter or 10-9 meters. |
| Node: 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. |
| Noise: 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 (NEP): The noise of optical receivers,
or of an entire transmission system, is often expressed in terms of noise
equivalent optical power. |
| Noise Figure (NF): The ratio of the output signal-to-noise
ratio 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 single-mode
fiber deployed. It is designed to have a zero-dispersion
wavelength near 1310 nm. |
| Nonlinearity: 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, SRS, FWM, SPM, XPM,
and Intermodulation. |
| Non Zero-dispersion-shifted
Fiber (NZ-DSF): A dispersion-shifted
single-mode fiber that has the zero-dispersion
wavelength near the 1550 nm window, but outside the window actually
used to transmit signals. This strategy maximizes bandwidth while
minimizing fiber nonlinearities. |
| NRZ: Abbreviation for nonreturn to zero. A common means of encoding
data that has two states termed “zero?and “one?and no neutral or rest
position. |
| ns: Abbreviation for nanosecond. One billionth of a second or 10-9 seconds. |
| NTSC: 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. |
| Numerical
Aperture (NA): 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 = sin a, where a is the acceptance
angle. NA also describes the angular spread of light from a central
axis, as in exiting a fiber, emitting from a source,
or entering a detector. |
|
| nW: Abbreviation for
nanowatt. One billionth of a Watt or 10-9 Watts. |
| Nyquist
Frequency: The lowest sampling
frequency that can be used for analog-to-digital conversion 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. |
| NZ-DSF: See non
zero-dispersion-shifted fiber. |
