15 Glossary

A

AAC (Advanced Audio Coding)

An audio compression scheme defined as part of the MPEG-2 standard (also known as MPEG- 2 AAC or MPEG-2 NBC, or Not Backwards Compatible). It offers better sound and a compression ratio that is superior by roughly 30 percent compared to the MPEG-1 MP3 format.

AC (alternating current)

An alternating current is an electrical current whose magnitude and direction vary cyclically, as opposed to DC (direct current), whose direction remains constant.The usual waveform of an AC power circuit is a sine wave, as this results in the most efficient transmission of energy. However certain applications use different waveforms, such as triangular or square waves.

Amplifier

A device, either a single stage or a large scale circuit with multiple stages for creating gain, i.e. it makes small signals larger.

Antenna

A device, such as a rod or wire, which picks up a received radio frequency signal or radiates a transmitted RF signal.

Audio output

High-level (speaker) or line-level (RCA) signals sent from one system component to another; or the high-level signal from an amplifier to the system speakers.

AUX

Auxiliary input that allows you to connect portable audio devices.

B

Bass

The lowest three octaves of the audio band. Low bass is the bottom octave (20-40Hz), mid- bass is the middle octave (40-80Hz), and upper bass is the 80-160Hz octave.

Bit / bits

A bit is a binary digit, taking a value of either 0 or 1. For example, the number 10010111 is 8 bits long.

Bit rate

Bit rate is the number of bits that are conveyed or processed per unit of time.The bit rate is usually measured in some multiple of bits per second (kilobits per second: kbps).The term bit rate is a synonym for data transfer rate (or simply data rate).

Bluetooth

A short-range wireless protocol that is meant to allow mobile devices to share information and applications without the worry of cables or interface incompatibilities.The name refers to a Viking King who unified Denmark. Operates at

2.4GHz. For more information, see bluetooth. com.

C

CBR (constant bit rate)

With CBR the encoder spends the same amount of bits on each frame, regardless of how much it may really need. Disadvantage of CBR: Bits are wasted in case of absolute blackness of a picture or complete silence in an audio frame. And pictures or audio frames with a lot of elements may need those bits.

CD (Compact Disc)

Format developed by Phillips, Sony, and Pioneer for conveying music and data. CDs record information by deforming the inner metal foil on the disc with tiny micro pits burned in by a laser.

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Philips WAC7505 user manual Glossary