Universal Audio 2192, Руководство пользователя

Страница: 46 / 55

Glossary of Terms
__________________________________________________________
- 42
-
A/D - An acronym for “Analog to Digital,” referring to the conversion of analog signal to digital.
ADAT - An acronym for “Alesis Digital Audio Tape.” ADAT was the name given to the Alesis-branded
products of the 1990s which recorded eight tracks of digital audio on a standard S-VHS video cassette.
The term now generally refers to the 8-channel optical connection that is used in a wide range of digital
products from many manufacturers.
AES - (sometimes written as “AES/EBU”) The name of a digital audio transfer standard jointly developed by
the American-based Audio Engineering Society and the European Broadcast Union. Designed to carry two
channels of 16-, 20- or, 24-bit digital audio at sampling rates of up to 192kHz, the most common AES
physical interconnect utilizes a 3-conductor 110 ohm twisted pair cable, terminating at standard XLR
connectors. (See “Dual Wire” and “Single Wire”)
Analog - Literally, an analog is a replica or representation of something. In audio signals, changes in
voltage are used to represent changes in acoustic sound pressure. Note that analog audio is a continuous
representation, as opposed to the quantized, or discrete “stepped” representation created by digital
devices. (See “Digital”)
Balanced - Audio cabling that uses two twisted conductors enclosed in a single shield, thus allowing
relatively long cable runs with minimal signal loss and reduced induced noise such as hum.
Bit - A contraction of the words “binary” and “digit,” a bit is a number used in a digital system, and it can
have only one of two values: 0 or 1. The number of bits in each sample determines the theoretical
maximum dynamic range of the audio data, regardless of sample rate being used. Each additional bit adds
approximately 6 dB to the dynamic range of the audio. In addition, the use of more bits helps capture
quieter signal more accurately. (see “Sample” and “Dynamic range”)
Bit depth - (see “Bit resolution”)
Bit resolution - Used interchangably with “bit depth,” this is a term used to describe the number of bits
used in a digital recording. The 2192 converts analog audio and transmits digital audio with a resolution
of 24 bits (thus yielding a theoretical dynamic range of approximately 145 dB), the highest resolution in
common use today. (see “Dynamic range”)
BNC - A bayonet-type coaxial connector often found on video and digital audio equipment, as well as on
test devices like oscilliscopes. In digital audio equipment, BNC connectors are normally used to carry word
clock signals between devices. BNC connectors are named for their type (Bayonet), and their inventors,
Paul Neil and Carl Concelman. The 2192 provides six BNC connectors: two for word clock input, and four for
word clock output. (see “Word clock”)
Class A - A design technique used in electronic devices such that their active components are drawing
current and working throughout the full signal cycle, thus yielding a more linear response. This increased
linearity results in fewer harmonics generated, hence lower distortion in the output signal.
Clock - In digital audio or video, a clock serves as a timing reference for a system. Every digital device
must carry out specified numbers of operations per period of time and at a consistent speed in order for the
device to work properly. Digital audio devices such as the 2192 normally have an internal clock, and are
also capable of locking to external clock routed from other digital devices. In order to avoid signal
degradation or undesirable audible artifacts, it is absolutely critical that all digital devices that are
interconnected in a system be locked to the same clock.
Clock distribution – Refers to the process of routing a master clock signal (either from an internal clock or
an external source) to multiple devices by means of multiple outputs, thus removing the need to cascade
the clock through external devices, which can degrade the signal. Clock distribution is one of the functions
of the 2192.