Orban OPTIMOD-FM 5500 Operation Manual page 73

OPTIMOD-FM DIGITAL
D) Navigate to Setup > I/O C
to produce 100% composite modulation (usually ±75 kHz carrier deviation) as
indicated on a modulation monitor or analyzer connected to your FM trans-
mitter's output.
If you set the composite output level correctly in step 15 (page 2-19) of
Quick Setup, you should see the 5500's composite level meter indicate
100% modulation when the AI R
portant to have set the composite output level correctly in this earlier
step. This will correctly match the 5500's composite limiter threshold to
the FM carrier deviation produced by the transmitter and will ensure that
the 5500's headroom is used correctly. If you are not sure whether the
5500's composite output level was set correctly, refer to step (7.H) on
page 2-32. Use "tone" method to set modulation. This uses the 5500's in-
ternal tone oscillator.
7. Set the digital input reference level.
[Skip this step if you will not be using the digital input.]
Refer to the notes in step 6 above.
A) Navigate to Setup > I/O C
B) Apply a 50 Hz sine wave the 5500's digital input (usually through an STL) and
set the level of the tone to correspond to 100% peak modulation of the com-
posite stereo baseband signal. This level should be the same as the maximum
peak output level produced by the FM audio processor driving the 5500.
C) Navigate to Setup > I/O C
to produce 100% composite modulation (usually ±75 kHz carrier deviation) as
indicated on a modulation monitor or analyzer connected to your FM trans-
mitter's output.
8. Activate the L/R Peak Limiter (optional)
A) Press the Modify button.
B) If you do not see the L/R L
pears.
C) Set the control to I
This activates a peak limiter similar to the one in Orban's 8218 and 5518
Stereo Encoders. The limiter controls peaks with a combination of look-
ahead limiting and band-limited clipping. There are two limiters, operat-
ing independently on the left and right channels. They are intended only
to remove overshoots caused by the STL. If used for more than 3 dB of
peak reduction, they can cause audible side effects. To minimize audible
distortion, it always better to minimize overshoots in the STL itself in-
stead of relying on the L/R peak limiter to remove them.
9. Activate the Composite Limiter (optional)
A) Press the Modify button.
> A I C
ALIB NLG N
control is set correctly. It is very im-
EF
> D I C
ALIB IG N ALIB
> D I C
ALIB IG N ALIB
soft button, press the Next button until it ap-
IM
.
N
> AI R . Adjust the AI R
ALIB EF
> I and set the input to D
NPUT
> DI R . Adjust the DI R
EF
2-25
INSTALLATION
control
EF
.
IGITAL
control
EF