Glossary
Term | Main definition |
---|---|
Photodiode |
A component that converts light energy into electrical
energy. The photodiode is used as the receiving end of a
fiber-optic link.
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Photon |
A basic unit of light; the smallest quantum particulate
component of light.
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Physical bus topology |
A network that uses one network cable that runs from
one end of the network to the other. Workstations connect
at various points along this cable. These networks
are easy to run cable for, but they are typically not as
reliable as a star topology. 10Base-2 Ethernet is a good
example of a network architecture that uses a physical
bus topology.
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Physical contact (PC) |
Description for a connector that places an optical fiber
end in direct physical contact with the optical fiber end
of another connector.
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Physical mesh topology |
A network configuration that specifies a link between
each device in the network. A physical mesh topology
requires a lot of cabling and is difficult to reconfigure.
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Physical ring topology |
A network topology that is set up in a circular fashion.
Data travels around the ring in one direction, and each
device on the ring acts as a repeater to keep the signal
strong as it travels. Each device incorporates a receiver
for the incoming signal and a transmitter to send the
data on to the next device in the ring. The network is
dependent on the ability of the signal to travel around
the ring. Cabling a physical ring topology is difficult
because of the amount of cable that must be run. FDDI
is an example of a network that can be wired to use a
physical ring topology.
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Physical star topology |
A network in which a cable runs from each network
device to a central device called a hub. The hub allows
all devices to communicate as if they were directly connected.
The network may logically follow another type
of topology such as bus or ring topology, but the wiring
is still a star topology.
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Physical topology |
The physical layout of a network, such as bus, star, ring,
or mesh.
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Picofarad |
One millionth of one millionth of a farad. Abbreviated pf.
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Pigtail |
(1) A short length of fiber with a permanently attached
device, usually a connector, on one end. (2) A fiber-optic
cable assembly consisting of a connector or hardware
device (such as a light source package installed by a
manufacturer) on one end and an unterminated fiber at
the other end. Normally found in applications wherein
a splice is convenient for terminating a device with a
connector. Also used when the loss characteristics of the
connector must be known precisely. For instance, a splice
of .03dB might be reliably predicted and controlled,
but the variability of most commercially available terminations
is unacceptable, so a precharacterized cable
assembly is cut into a pigtail and attached to the device
through splicing.
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Pin | Pin Contact - Refers to the conductive element in a connector.
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Pinout scheme |
The pinout scheme is the pattern that identifies which
wires in a UTP cable are connected to each pin of a
connector.
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Planar waveguide |
A waveguide fabricated in a flat material such as a
thin film.
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Plastic fiber |
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Plastic fiber |
Optical fiber having a plastic core and plastic cladding
rather than using glass.
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