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PROGRAM LINE OUTPUTS
DAVID IV digital and analog line outputs are available simulta-
neously and are independently adjustable and assignable to a
specific output characteristic. These outputs, found under
Set-
up
, have options described as follows:
20kHz Flat
20k-Flat
is a full-range (20kHz) output that comes directly from
the output of the broadband peak limiter. This output is suita-
ble for any form of full-power-bandwidth digital radio broad-
casting, for audio production and recording, or for high quality
streaming. The
20k-Flat
output option does
not
include the in-
dependent HF limiting afforded by adaptive pre-emphasis,
15kHz low-pass filtering, nor will it incorporate the HD Radio
delay when it is implemented for the multiplex output.
Pre-Emphasized
FM Output
When the
FM-Pre
output characteristic is selected, the output is
configured to feed an FM exciter that has a built-in stereocoder
(stereo-gen). The line output will include adaptive pre-
emphasis and the 15kHz low-pass filtering required for stereo
pilot protection, and is pre-emphasized in this mode. This
means that any pre-emphasis option in the exciter should be
switched OFF. If HD Radio delay is enabled, the
FM-Pre
line
output will be delayed just as it is for the multiplex output.
Normalized
(Flat) FM Output
The
FM-Flat
output characteristic is similar to
FM-Pre
, except
that the signal has been ‘normalized’ with a de-emphasis net-
work to restore a flat frequency characteristic. This output
would be the proper feed to an FM exciter that does its own
pre-emphasis. Although the audio response from this output is
flat, it still includes the 15kHz low-pass filter and independent
HF limiting to protect the spectrum and the stereo pilot, plus it
will also have the HD Radio delay if it is enabled.
Both FM modes retain full benefit of independent HF limiting to
protect the pre-emphasis curve, that curve specified by the set-
ting of the DAVID IV’s own stereo-gen, whether used or not.
AES Digital
Line Output
The male XLR connector labeled
AES DIGITAL OUTPUT
is a bal-
anced, transformer-coupled, 24-bit digital stereo program out-
put conforming to the AES3 (AES/EBU) specification. The
AES
Output Rate:
is selected on the
Setup
Webpage, or under the
Set-
up / Sample Rate Converter
front-panel menu. The digital output
rate may be selected either to follow the input rate, or to fix the
output sample rate at 32kHz, 44.1kHz, 48kHz, or 96kHz.
The digital output level shown below the slider control is the
program peak level, which has been limited by the DAVID IV to
the 100% modulation point.
The
Digital Level (dB):
is variable between 0dBFS and –20dBFS.
‘FS’ refers to digital-full-scale, or as high as the digital signal
can go. This means that audio peaks in the program signal,
which have been limited to 100% modulation, can assume any
level between digital-full-scale and a value 20dB below this.
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