Orban OPTIMOD-FM 8600Si, Operating Manual

Page: 77 / 356

OPTIMOD-FM DIGITAL INSTALLATION
2-21
Turn the knob to set the maximum desired output level in units of dB
below full-scale (dBFS).
The “true peak” limiter at the end of the 8600Si’s HD processing chain is
oversampled at 256 kHz and will prevent overshoots from exceeding
0.3 dB, even after sample rate conversion or D/A conversion.
To mitigate codec-induced overshoots in HD Radio applications, you may
wish to set the level below 0 dBFS.
Do not use the Digital Output level control to match the loudness of the
FM analog and HD audio at the radio.
Instead, use the HD L
IMITER
D
RIVE
control in the active Processing Preset to do this as the last step after you
have customized to preset to your liking. Using the
HD L
IMITER
D
RIVE
con-
trol prevents unnecessary gain reduction from occurring in the HD proc-
essing’s peak limiters.
BS.1770 Loudness Control: Some countries now require the integrated
loudness of digital radio transmissions to be equal to a “target loudness”
set by the regulatory authority of the country in question. The 8600Si
provides a “BS.1770 Safety Limiter” for this purpose. The BS.1770 Safety
Limiter should be defeated in HD Radio installations.
Note that when the BS.1770 Safety Limiter is active and
D
IGITAL
O
UTPUT
#1
is set as the “BS.1770 reference output,” the D
IGITAL
O
UTPUT
#1 level con-
trol does not affect loudness, but only sets the peak headroom. For ex-
ample, if the
D
IGITAL
O
UTPUT
#1
control is set to –2 dBFS, peaks will not
exceed –2 dBFS but the BS.1770 loudness will remain calibrated to the
value of
D
IALNORM
that you specify in I/O Setup. Quick Setup does not in-
clude setup of the BS.1770 safety limiter; see step 12on page 2-35 for
setup instructions.
E) Set the analog output level.
a) Press the
Next
button.
b) [Skip this step if you are not using the analog output.]
Turn the knob to set the desired analog output level corresponding to
100% modulation, in units of dBu (0 dBu = 0.775 Vrms).
The most accurate way to set this control is by observing a modulation
monitor or analyzer connected to your transmitter.
c) Press the
Next
button.
If you activated the modulation setup tone in step (A)a) on page 2-20,
the tone will turn off automatically.
F) Press the
Next
button.
You have now completed the guided Quick Setup procedure and are in
the normal
Recall
P
RESET
screen. However, if your country requires you
to comply with the multiplex power ceiling specified in ITU-R BS412-9,
you will also need to set up the 8600Si’s Multiplex Power Controller by
following the instructions in step 1 on page 2-23.