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PABX - Private Automatic Branch Exchange
Packet - Bits grouped serially in a defined format, containing
a command or data message sent over a network.
PAM5x5 - Signal encoding scheme used in the Ethernet
100Base-T2 and 1000Base-T media systems.
Patch Cord - A flexible piece of cable terminated at
both ends with connectors. Used for interconnecting circuits
on a patch panel or cross connect.
Patch Panel - A passive device, typically flat plate
holding feed through connectors, to allow circuit arrangements
and rearrangements by simply plugging and unplugging patch cables.
Pathway - A facility for the placement of telecommunication
or networking cables.
PBX - Private Branch Exchange
PC - Personal Computer
PCC - Premises Communication Cable, CSA Cable Designation.
PDN - Public Data Network
Peak - The maximum instantaneous value of a varying current
or voltage.
Pedestal - A device, usually mounted on the floor, which
is used to house voice/data jacks or power outlets at the point
of use. Also referred to as a monument, tombstone, above floor
fitting or doghouse.
Periodicity - Uniformly spaced variations in the insulation
diameter of a transmission cable that result in reflections
of a signal.
Phase - An angular relationship between waves.
Phase Modulation (PM) - One of three basic methods (see also
Amplitude and Frequency Modulation) of adding information to
a sine wave signal in which its phase is varied to impose information
on it.
Phase Shift - A change in the phase relationship between
two alternating quantities.
Photo detector - Used on the receiving end of a fibre
optic cable to convert light energy into electrical energy.
PHY - Physical Layer device.
Physical Layer - Layer one of the seven layer ISO Reference
Model for Open Systems Interconnection. The physical layer is
responsible for the transmission of signals, such as electrical
signals, optical signals, or radio signals, between computing
machines.
Pico - Prefix meaning one millionth of one millionth.
Picofarad - One millionth of one millionth of a farad.
Abbreviated "pf".
Pin-diode - A photodetector used to convert optical signals
to electrical signals in a receiver.
Plastic - High polymeric substances, including both natural
and synthetic products, but excluding the rubbers that are capable
of flowing under heat and pressure.
Plastic Fibre - An optical fibre made of plastic rather
than glass.
Plasticizer - A chemical added to plastics to make them
softer and more flexible.
Plenum - The air handling space between the walls, under
structural floors, and above drop ceilings used to circulate
and otherwise handle air in a building. Such spaces are considered
plenums only if they are used for air handling. Work spaces
are generally not considered plenums.
Plenum Cable - A cable that is rated as having adequate
fire resistance and low smoke producing characteristics for
use in air handling spaces (plenum).
Plug - A male connector.
PMD - Physical Media Dependent or Polarisation Model
Dispersion
POF - Plastic Optical Fibre.
Polybutadiene - A type of synthetic rubber often blended
with other synthetic rubbers to improve their properties.
Polyethylene - A thermoplastic material having excellent
electrical properties.
Polymer - A substance made of repeating chemical units
or molecules. The term is often used in place of plastic, rubber,
or elastomer.
Polypropylene - A thermoplastic material similar to polyethylene
but somewhat stiffer and with a higher softening point (temperature).
Polyurethane - Broad class of thermoplastic polymers with good
abrasion and solvent resistance. Can be solid or cellular (foam).
Polyvinyl Chloride (PVC) - A general purpose thermoplastic
used for wire and cable insulation and plastics. PVC is know
for high flexibility. Often used in nonplenum wire insulation
and cable jackets. A modified version of the material may be
found in jacketing of some plenum rated cables.
POTS - Plain Old Telephone System
Potting - Sealing by filling with a substance to exclude
moisture.
Power Level - The difference between the total power
delivered to a circuit, cable, or device and the power delivered
by that device to a load.
Power Ratio - The ratio of power appearing at the load
to the input power. Expressed in dB.
Premise Cabling - The entire cabling system on the user's
premises used for transmission of voice, data, video and power.
Pre-wiring - Wiring installed before walls and ceilings
are enclosed.
Private Branch Exchange (PBX) - A private telephone switching
system, usually located on a customer's premises connecting
a common group of lines from one or more central offices to
provide service to a number of individual phones. Now used interchangeably
with PABX (Private Automatic Branch Exchange).
Propagation Delay - Time required for a signal to pass
from the input to the output of a device.
Protector - A device that limits damaging voltages on
metallic conductors.
Protocol - A set of agree-upon rules and message formats
for exchanging information among devices on a network.
PSELFEXT - Power Sum Equal Level Far End Crosstalk
PSNEXT - Power Sum Near End Crosstalk
Public Data Network - A network established and operated
for the specific purpose of Providing data transmission services
to the public.
Public Switched Network - Any common carrier network
that provides circuit switching between public users, such as
the public telephone network, telex or MCI's Execunet.
Pull Strength, Pull Tension - The pulling force that
can be applied to a cable without affecting the specified characteristics
of the cable.
Pulse - A current or voltage which changes abruptly from
one value to another and back to the original value in a finite
length of time.
Pulse Code Modulation (PCM) - The most common method
of representing an analog signal, such as speech, by sampling
at a regular rate and converting each sample to an equivalent
digital code.
PVC - Polyvinyl Chloride
PVDF - Polyvinylidene Fluoride |
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