Philips NP2500/05 ユーザーズマニュアル

37

Digital Audio

Digital Audio is a sound signal that has been 

converted into numerical values. Digital sound 

can be transmitted through multiple channels. 

Analog sound can only be transmitted through 

two channels.
Duplex (half/full)

Full duplex is the ability to send and receive 

data simultaneously. Duplex is synonymous 

with full duplex. Example: when a modem 

operates in full-duplex mode, it can transmit 

data in two directions simultaneously. In 

half-duplex mode it can transmit data in two 

directions, but not simultaneously.

E

Encryption key

An encryption key is an alphanumeric series 

that enables data to be encrypted and then 

decrypted so it can be safely shared among 

members of a network.

F

Frequency

The property or condition of occurring at 

frequent intervals. In sound, this simply refers 

to the regular occurrence of compression and 

rarification of air that we experience as sound. 
Frequency Response

Is the range of frequencies that a speaker 

reproduces, lowest frequency to the highest. 

While the optimal normal is 20-20,000 Hz 

(Hertz), the range of human hearing for 

individuals is often much more restricted. 

A good full-range speaker system however, 

reproduces as much of this range as possible 

to cover all variations. Individual drivers are 

limited to reproduce only that part of the 

spectrum for which they were made, so their 

response is limited, but still a necessary point 

to consider when designing a complete sound 

system.

being played, and then downloads the title, 

artist, and track list.
Coaxial

A single copper conductor, surrounded with 

a layer of insulation, covered by a surrounding 

copper shield and finally, an insulating jacket. 

An unbalanced transmission line with constant 

impedance. In audio, this type is commonly 

used for low level, line signals terminated in 

RCA connectors.

Compression

In audio terms, this is a process of temporarily 

or permanently reducing audio data for more 

efficient storage or transmission. A temporary 

reduction in file size is called ‘non-lossy’ 

compression, and no information is lost. A 

permanent reduction in file size (such as with 

MP3 files) is called ‘lossy’ compression, and 

involves discarding unnecessary information 

which is irretrievably lost.

D

DC (direct current)

Direct current or continuous current is 

the constant flow of electric charge. This is 

typically in a conductor such as a wire. In 

direct current, the electric charges flow in 

the same direction, distinguishing it from AC 

(alternating current).
Decibel (dB)

A unit of measure used to express relative 

difference in power or intensity of sound.
DHCP

DHCP stands for Dynamic Host Configuration 

Protocol. It is a protocol for assigning dynamic 

IP addresses to devices on a network. 
Digital

A method to encode information using a 

binary code of 0s and 1s. Many wireless 

phones and networks use digital technology.

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