Orban OPTIMOD 8400 - Page 137

OPTIMOD-FM OPERATION
3-29
The ratio of L–R/L+R of the enhanced signal tries to exceed the threshold set by the
L-R/L+R Ratio Limit control.
In this case, the enhancer prevents further enhancement in order to prevent
excess L–R energy, which can increase multipath distortion.
The stereo enhancer has the following controls:
Stereo Enhancer Controls
Basic/Intermediate Name Advanced Name Range
Amount Amount 0.0 ... 10.0
Enhancer In/Out Out/In
Ratio Limit Ratio Lim 70 … 100%
Diffusion Diffusion Off, 0.3 ... 10.0
Style Style 222/Delay
Depth Depth 0 … 10
Rumble Filter
30 Hz HPF
30 Hz HPF Off/On
Phase Rotator Phase Rotat Out/In
Table 3-3: Stereo Enhancer Controls
Amount sets the maximum spatial enhancement.
Enhancer In/Out
bypasses the stereo enhancer. Out is equivalent to setting the Amount
to 0.
L-R/L+R Ratio Limit
sets the maximum amount of enhancement to prevent multipath
distortion. However, if the original program material exceeds this limit with no enhance-
ment, the enhancer will not reduce it.
Diffusion
applies only to the Delay enhancer. This control determines the amount of de-
layed L–R added to the original signal.
Style
sets one of two stereo enhancer types: 222 or Delay.
Depth
sets the delay in the delay line. It applies only to the Delay enhancer.
Rumble Filter 30 Hz HPF
determines if a 30 Hz 18 dB/octave highpass filter will be
placed in-circuit before other processing. Although not a stereo enhancer control, it is
found on the stereo enhancer page (for convenience) because, like the stereo enhancer, it
can be adjusted without eliminating
Less/More functionality.
Phase Rotator
is not a stereo enhancer control. It determines if the phase rotator will be
in-circuit. The purpose of the phase rotator is to make voice waveforms more symmetri-
cal. This can substantially reduce distortion when they are peak limited by the 8400’s
back end processing.
In most cases, we recommend that the phase rotator be left active. However,
because it can slightly reduce the clarity and definition of program material,
you can defeat it if you are operating the 8400 conservatively and not at-
tempting to achieve very high on-air loudness.