DCS 900E User Manual page 13

dCS 900E / 902E User Manual
dCS Ltd
Word Length
Noise Shaping
Overload Level
Manual part no: DOC0029021E1
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dCS
(inside the UK replace + 44 with 0)
The AES/EBU format accommodates data up to 24 bits. If a shorter word is
needed and the extra bits are just ignored, the result is typical "digital" sound
due to the abrupt chopping off of the low level signal information.
To avoid this, the dCS 900 / 902 allows proper truncation of the data and uses
Noise Shaping to maintain low level performance. See the section on
Length Reduction" on page 50 for some background on this. If you do use
Word Length truncation, make sure that
without realising it.
Pressing the Word Length
sequence:
24, 23, 22, 21, 20, 19, 18, 17, 16, 24,
The Word Length is briefly shown on the main display, and if a setting other than
the maximum is set, the word length LED (above the button) lights.
Noise Shaping is a technique which improves the noise performance of the ADC
in the audio band by moving the quantisation noise energy (introduced by
reducing the word length) from the middle of the band, where the ear is most
sensitive, to the top end or ultrasonic region, where the ear is less sensitive or
insensitive. See the section
background.
Pressing the Noise Shaping
Shaping characteristics. The characteristic is shown briefly on the main display.
Auto
Off
1st
3rd
9th
The noise shaping LED (above the button) lights when the setting is other
than Auto.
The Overload Level button is dual function – on its own
panel) it sets the level at which overloads are detected by the unit. With the
other menu buttons (white
Overload detection is normally set to full scale. The detection level may be
reduced in 0.1dB steps down to -3dB0 by pressing the
repeatedly or holding it down. The set level is shown on the display for a few
seconds. The overload level LED (above the button) lights when the setting is
other than full scale (0.0dB0).
For Menu operation as the
Menu" on page 18.
Manual for Software Versions 1.3x to 1.5x
-
-
Noise Shaping
button repeatedly cycles the word length through the
"Word Length Reduction"
button repeatedly cycles the unit through 5 noise
Unit sets noise shaping automatically, depending
on word length:
24 bits – no noise shaping
st
20 to 23 bits – 1 order noise shaping
rd
16 to 19 bits – 3 order noise shaping
No noise shaping
st
1 order noise shaping
rd
3 order noise shaping
th
9 order noise shaping
Menu Step
type on the front panel) it is the menu
Step button, see the section
Page 13
th
12 June 2000
"Word
is not set to
etc.
on page 50 for more
(blue type on the front
Step button.
Overload Level button
"The Software – The
Document No: OS-MA-D0002-902.1E1
email to: more@dcsltd.co.uk
web site: www.dcsltd.co.uk
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