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Composite
The stereo
MPX generator output levels from both of the composite output BNC jacks can be adjusted separately
using the
Output 1
and
Output 2
variable controls in the
Composite Level
group over a range of 0 to 10 volts in
precise 0.05v increments.
NOTE: Always use typical program material and
a calibrated modulation monitor to properly set
modulation. To aid quick adjustment, it
sometimes helps to advance the
Clipper Drive
control before adjusting the composite ou
tputs.
Note that reference line
-up tones applied at the
Omnia’s input cannot be used since the RMS
level of a steady state tone does not
crest
at 100%
modulation.
Pilot Level
sets the 19kHz pilot injection level up
to 12.0%, in 0.1% steps, relative to 100%
modulation. To defeat the pilot, simply adjust the
Pilot Injection control to “0.0” and the pilot will
be off.
Composite Output Submenu (Basic Tab)
Pilot Phase
This parameter sets the phase relationship between the 19 kHz pilot and the 38 kHz suppressed carrier.
The system default is 0.0 degrees. The performance of the DSP based digital stereo generator is theoretically perfect,
however should the phase need adjustment in order to offset time domain errors in the overall transmission system,
the pilot phase can be adjusted ±32º, in 1º increments. We recommend that a calibrated modulation monitor be used
for this adjustment.
Stereo Separation
The stereo “sound field” can be reduced by 3 dB or 6 dB to suppress processing
-
induced
multipath that
can occur in certain terrain and within certain transmission systems when heavy processing is used.
When a setting of
-3 dB
or
-6 dB
is used, the amount of L-
R (perceived stereo effect) is also reduced. However in
difficult RF signal coverage areas, the amount of perceived multipath is reduced as well, resulting in the perception
of a much cleaner overall signal with better penetration and coverage. The Omnia.11 defaults to a setting of
Stereo
,
using the full L-
R signal for maximum separation. We suggest t
hat you leave it in that mode, but the other settings
are available for those who wish to experiment, including a setting of full
Mono.
Sideband Mode
The normal setting for the stereo generator is the
DSB
setting
which provides the full double
-
sideband, s
uppressed carrier L
-R signal.
The special
SSB
setting provides a single-
sideband, suppressed carrier L
-
R signal that can help reduce multipath and
provide increased protection to the baseband spectrum. Please check with your local regulatory agency before
using
this mode since it has not been standardized
as of this writing.
For more information please see Frank Foti’s white paper, available on our website
at:
http://www.omniaaudio.com/mpx-ssb-white-paper
