Glossary - Sencore DigiPro DA795 Operation Manual

DA795 DigiPro Digital Audio Analyzer
This section defines common terms used in this manual.
ADAT – Alesis Digital Audio Tape. A digital audio transmission format invented and patented
by Alesis, originally for use with their digital tape recorders. Format usually runs at 48 kHz
sample rate, with each frame containing up to eight channels of 24-bit digital audio. The
physical connection uses fiber optics, using the same optical cable as Toslink.
ADC (Analog to Digital Converter) – An ADC converts an analog signal into the digital
domain. It runs at the desired sample rate – or, if over-sampling is used, at a multiple of the
desired sample rate. At each sample time, the level of the analog signal is measured and
converted into a number. (See Word Length).
AES/EBU –AES3 and IEC-985 define a balanced line signal that normally uses XLR connectors
to interconnect equipment. This format takes its name from the two principal advocates and
is the professional audio data interface. This standard interleaves useful non-audio channel
status data with the audio data, to provide information on the sampling rate, etc.
Bit Depth – See Word Length.
Clock rate – See Sample Rate.
DAC (Digital to Analog Converter) – A DAC converts a digital signal back to analog. The
samples are non-continuous (by definition), since there are a finite number of levels (see
Word Length) and a finite number of samples in a second (see Sample Rate), so after
conversion the numbers need to be smoothed (filtered) to get back to analog.
DAW – Digital Audio Workstation. A system designed to record, edit, and play back digital
audio. A key feature of DAWs is the ability to freely manipulate recorded sounds, much like
a word processor manipulates typed words. Refers to a general combination of audio
multitrack software and high-quality audio hardware —the latter being a specialized audio
converter unit which performs some variety of both analog to digital (ADC) and digital to
analog (DAC) conversion. Performs the same functions as a common sound card, but is an
external unit, which records far less noise (hum, static), higher resolution, and better dynamic
range.
dB FS - Decibel level of a digital audio signal, referenced to full scale digital output. In digital
systems, 0 dB FS equals the highest level (number) that the employed word length is capable
of representing.
DigiPro – See DA795.
Dither – As a signal that is being converted from analog to digital gets to lower and lower levels,
and finally approaches the least significant bit, more and more information starts to be lost.
The quietest sine wave you can play back is one bit in amplitude—and therefore plays back
as a square wave. The lower the signal levels, the higher the relative distortion. Oddly, by
adding low-level noise to the incoming signal (dither), the information starts coming through
better, at the cost of more noise. By adding dither, we trade a little low-level hiss for a big
reduction in distortion. The theory behind this is a little messy, but imagine looking through
your spread fingers. You see some things, but some things are blocked by your fingers. Now
wiggle your hand side to side, and you can see through everything through your fingers, at
the cost of some blurring.
DA795 – DigiPro Digital Audio Analyzer.
Form7494

GLOSSARY

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Operation Manual