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PAL
- Abbreviation
for Phase Alternate Line. PAL is the dominant format in
the World for analog television broadcasting and video
display and is based on a 625 line, 50 field/25 frames a
second, 50HZ system. The signal is interlaced, like
NTSC into two fields, composed of 312 lines each. Two
distinguishing features are: (1) A better overall
picture than NTSC because of the increased amount of
scan lines. (2) Since color was part of the
standard from the beginning, color consistency between
stations and TVs are much better. There is a down side
to PAL however, since there are fewer frames (25)
displayed per second, sometimes you can notice a slight
flicker in the image, much like the flicker seen on
projected film. Since PAL and its variations have such
world domination, it has been nicknamed "Peace At
Last", by those in the video professions. Countries
on the PAL system include the U.K., Germany, Spain,
Portugal, Italy, China, India, most of Africa, and the
Middle East.
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Passive
- Not active. A passive crossover uses no external
power and results in insertion loss. A passive speaker
is one without internal amplification.
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Passive
Radiator - A
radiating surface (usually similar to a conventional
speaker cone) that is not electrically driven but shares
the same air space in a sealed cabinet with an
electrically driven loudspeaker. This arrangement is
functionally similar to a loudspeaker with a vented
(ported) cabinet, with the passive radiator serving the
duties of the air in the port.
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Parametric -
Equalizer with adjust-able parameters, such as center
frequency and bandwidth (Q), as well as amplitude.
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PCM
- See Pulse Code Modulation.
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Peak
Power - The
recommended highest power capacity of an amplifier or
speaker.
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Phase
- In audio, phase refers to the timing relationship of
two or more waves. It's especially important to be sure
that your speakers are wired "in phase." This means
that the drivers of your speakers are moving in and out
at the same time. If your speakers are "out of phase"
there will be significantly less bass, and a loss of
stereo imaging.
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Picture
Height - (As
in "lines per picture height"). Reference distance
measurement for resolution of TV screens, used for
horizontal as well as vertical discussion. This is so
chosen because resolution is correctly measured in the
largest circle that fits in the area referred to and for
a TV screen the diameter of such a circle equals "one
picture height."
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Piezo
- A type of speaker driver that creates sound when a
quartz crystal receives electrical energy.
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Pillerbox
- Black bars on all
four sides of the image. This occurs when a station
broadcasts an upconverted 4:3 aspect ratio program
within a 16:9 frame.
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Pink Noise
- Noise
that has equal energy in each octave.
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Pitch Resolution
- The clarity with which the pitch of (generally) bass
notes is perceived. Poor pitch resolution makes all
notes sound similar; good pitch resolution gives an
impression that you "can almost count the cycles."
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Pixel
- A Pixel is a
picture element. It is single smallest point on a
screen or chip surface that is used to construct a video
image. Pixels are arranged in rows and columns in order
to produce a complete image. A good analogy is that a
pixel has a similar relationship in the structure of a
video image as a living cell does in the structure of a
biological life form.
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Pixel
Density
- Pixel Density is
the actual amount of physical picture elements on a
screen surface or an LCD/DLP projection chip. LCD/DLP
projectors have a fixed number of pixels on their chips.
With reference to Video, the higher the native pixel
count, the higher the resolution capability of the video
display device. A native pixel count of 1024x768 (1,024
pixels across vs 768 pixels down) is sufficient for DVD.
However, 720p HDTV signals require a 1280x720 pixel
count to give you a one-for-one signal representation,
while a 1080i HDTV input signal needs a native pixel
count of 1920x1080 for a one-for-one representation of
the 1080i signal.
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Phono Plug
- Same as
an RCA-type plug.
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Planar-Magnetic Loudspeaker
- A flat,
panel-type speaker that radiates sound from both front
and back. This design looks similar to some
electrostatic designs but uses a widely dispersed
variant of the magnet-and-coil system found in typical
dynamic models. Because of this, there is less
electrical load on the amplifier, and thus these
speakers are less likely to cause erratic amplifier
behavior.
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Plasma
- Flat-panel display technology that ignites small
pockets of gas to light phosphors.
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Plug
- The male side of a connector is a plug. The female
side is a Jack.
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Polarity
- Identified as positive or negative for the 180-degree
phase difference within the same audio signal. Polarity
must be consistent when wiring speakers or audio
components together; negative always matches negative,
positive always to positive. To get them crossed at
some point will cause sound that is "out of phase" and
will limit frequency response.
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Port
- An aperture in a loudspeaker enclosure that helps
extend the usable low-frequency output. A ported
enclosure is also called vented or bass reflex.
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Ported Enclosure
- A type
of speaker enclosure that uses a duct or port to
increase low bass output.
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Power
Output - A
measure, usually in watts, of how much energy is
modulated by a component.
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Power
Response -
In loudspeakers, the integrated output in all
directions. In most rooms, the overall level of the
power response swamps the tonal effects of the direct
signal.
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Preamplifier -
A control and switching component that may include
equalization functions. The preamp comes in the signal
chain before the amplifiers.
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Precedence Effect
- When identical sounds come from two different speaker
systems, if the distance is great enough, the ear tends
to attribute all the sound to the near one. This
phenomenon is one reason that the surround-channel sound
in a DPL system is delayed relative to the main
channels. Similar to the Franssen effect, where
percussive bass signals have their localization
determined by the position of higher-frequency drivers
in a speaker system. Also known as the Haas effect.
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Pre Outs
- Connectors that provide a line-level output of the
internal preamp or surround processor.
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Pre
Outs/Main Ins
- Connectors on a receiver that provide an interruptible
signal loop between the output of the internal preamp or
surround processor portion of the receiver and the input
of the amplifier portion of the receiver.
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Pre/Pro
- A combination preamp and surround processor.
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Processors -
Anything that processes an incoming signal in some way.
Surround processors, for example, can decode a Dolby
Digital signal to send to an amp so you can hear it.
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Progressive Scanning
- Each frame of a video image is scanned complete, from
top to bottom, not interlaced. For example, 480p means
that each image frame is made of 480 horizontal lines
drawn vertically. Computer images are all progressively
scanned. Requires more bandwidth (twice as much
vertical information) and a faster horizontal scan
frequency than interlaced images of the same resolution.
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Projection System
- Display that projects image onto a screen.
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Projection Television Set
- A TV that employs either three CRT tubes or an LCD
arrangement to project an image on a special screen.
The most common are rear-projection models, which use
lenses and mirrors within a large box to project the
image to the inside of a translucent screen, the outside
of which faces the viewer. Less common are
front-projection models, which mount the projector
across the room from a conventional screen.
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Pulse
Code Modulation
- (PCM) a way to convert sound or analog information to
binary information (0s and 1s) by taking samples of the
sound and record the resulting number as binary
information. Used on all CDs, DVD-Audio, and just about
every other digital audio format. It can sometimes be
found on DVD-Video.
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PVR
- Personal Video Recorder. Marketing term for Video HDRs.
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