Orban OPTIMOD-FM 8500S Operating Manual page 233

OPTIMOD-FM DIGITAL
Samp Rate ("Sample Rate") sets the output sample rate of the digital-channel out-
put to 32, 44.1, 48, 88.2, or 96 kHz.
The 8500S's fundamental sample rate is always 64 kHz, but the internal
sample rate converter sets the rate at the 8500S's digital output. This ad-
justment allows you to ensure compatibility with downstream equipment
requiring a fixed sample rate.
A 32 kHz sample rate cannot represent frequencies higher than approxi-
mately 15 kHz. Therefore, setting the sample rate to 32 kHz automati-
cally forces the bandwidth to 15 kHz, regardless of the setting of the HD
B
ANDWIDTH
Word Leng (" Word Length") sets the word length (in bits) emitted from the digi-
tal-channel output.
The largest valid word length in the 8500S is 24 bits. The 8500S can also
truncate its output word length to 20, 18, 16, or 14 bits. The 8500S can
also add dither, which we recommend.
Dither turns on or off addition of "high-pass" dither before any truncation of the
output wordlength.
The amount of dither automatically tracks the setting of the W
L
ENGTH
noise in the midrange than does white PDF dither. However, unlike ex-
treme noise shaping, first-order noise shaped dither adds a maximum of
3 dB of excess total noise power when compared to white PDF dither. It is
thus a good compromise between white PDF dither and extreme noise
shaping.
In many cases, the source material has already been correctly dithered so
you will not need to add dither and can set this control to O
particularly if you use the Noise Reduction feature, the processing can
sometimes attenuate input dither to a point where it is insufficient to
dither the output correctly. In this case, you should add dither within the
8500S by turning this control on.
Sync determines if the sample rate appearing at the digital-channel output is
synced to the 8500S's internal clock, to an AES3 signal appearing at the 8500S's digi-
tal input, or to an AES11 signal appearing at the 8500S's sync input. S
separately for Digital Output 1 and Digital Output 2, allowing them to have differ-
ent sample rates.
The selections for each of the two AES outputs are I
I . I
NPUT
the same sample rate present at the 8500S's AES3 (audio) input. Likewise,
S
YNC
the source. I
8500S's internal clock and uses the S
output sample rate.
For a given AES3 output, the output sample-rate selector ("S
has no effect in the I
output reverts to internal sync at the sample rate that is preset by the
sample-rate selector for that output. Otherwise, the output sample rate
control.
control. This first-order noise shaped dither adds considerably less
sets a given AES3 output sample rate and synchronization to
NPUT
I
uses the AES11 sync input's sample rate and synchronization as
N
synchronizes the given AES3 output rate to the
NTERNAL
and S
NPUT
NTERNAL
setting to determine its
R
AMP ATE
I modes unless sync is lost. Then the
YNC N
OPERATION
ORD
. However,
UT
can be set
YNC
, and
, S I
YNC N
R ")
AMP ATE
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