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O
Ohm
Measure of resistance to current (impedance).
The lower the impedance of a speaker, the
harder it is to drive.
P
PCM (Pulse Code Modulation)
Pioneering form of digital recording.
R
RDS (Radio Data System)
RDS tuners can automatically tune in stations
according to the types of music (or talk) they
broadcast. RDS also enables a receiver to
display text messages and even graphics (usually
call letters and format information) that many
FM stations include on a sub-carrier signal
within their normal broadcast signal. Some RDS
equipped tuners can even override with trafc
alerts or emergency broadcasts, during playback
of other media - CD MD, or cassette. There are
other useful features too, many of which are
offered by the growing number of RDS stations.
RF (radio frequency)
An alternating current or voltage with a
frequency (or carrier wave) above about
100kHz. It is called radio frequency because
these frequencies have a capacity to be radiated
as electromagnetic waves by radio (and
television) stations.
Rip (ripping)
Using a software program that “grabs” digital
audio from a compact disc and transfers it to a
computer hard drive. The integrity of the data
is preserved, because the signal does not pass
through the computer sound card, and need
not be converted to an analog format. The
digital-to-digital transfer creates a WAV le that
can then be converted into an MP3 le.
Lossless compression
A system for reducing the number of data bits
(density) in a musical signal without corrupting
the original.
M
M4A
The audio le format used by Apple in their
iTunes Music Store often appears on your
system with the ‘.m4a’ lename extension. M4A
can produce better audio quality than MP3
using less physical space for the les.
MHz (Mega Hertz)
One million cycles per second.
Midrange
The middle three octaves (more or less) of the
audio band, where the ear is most sensitive,
usually between 160Hz-3kHz.
Mono (monaural)
The operation of an amplier in one channel
for both input and output. Can refer to an
amplier with only one channel of amplication
or operating in bridged mode. For low-
frequency amplication applications, it provides
better phase coherence and less distortion than
stereo operation.
MP3
A le format with a sound data compression
system. MP3 is the abbreviation of Motion
Picture Experts Group 1 (or MPEG-1) Audio
Layer 3. With the MP3 format, one CD-R or
CD-RW can contain about 10 times more data
than a regular CD.
Mute
A control found on receivers, and some mixers
or signal processing units that silences (mutes) a
signal path, or output.
Glossary
English
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