Optimod-AM 9400 V1.2 Operating Manual - Orban

2-30
INSTALLATION ORBAN MODEL 9400
10. Set output and configuration level.
This is a preliminary level adjustment. Later in this installation procedure, you
will set 9400 for the highest modulation level that your facility can produce. If
your transmission facility proved to have overshoot, tilt, or ringing when you
tested it in step 11 on page 2-31, you will have to go through the Transmitter
Equalizer adjustment procedure, which starts with step 12 on page 2-31.
A) Make sure that the transmitter is turned off.
B) Turn on the 400Hz calibration tone. To do this:
a) Navigate to SETUP > TEST.
b) Set the MODE to SINE.
c) Set SINE FREQ to 400 HZ.
d) Set TONE MOD to 50%.
e) Press the NEXT key.
f) Set TONE CHAN to L+R.
C) Set modulation.
a) Set to its minimum level the AOX 100% or DOX 100% control associated
with the output you are using to drive the transmitter under adjustment.
For example, the AO1 control is found in I/O CALIB > ANALOG1 > AO1 and
the DO1 control is found in I/O CALIB > DIGITAL1 > DO1 100%.
b) Turn the transmitter on.
c) Set the control you adjusted in step (a) to produce 40% modulation.
This leaves 2 dB of headroom to accommodate overshoot in the transmission
plant. This should suffice for most plants.
The most accurate way to set this control is by observing a modulation
analyzer or oscilloscope connected to your transmitter.
D) In SETUP > TEST, set the MODE to OPERATE.
E) Drive the 9400 with program material and observe the negative modulation
level. Trim the AOX 100% or DO X100% control associated with the output you
are using to drive the transmitter under adjustment so that you observe 99%
modulation on negative peaks.
Spend time observing the modulation with different program material. If
you see the peak modulation level vary significantly depending on program
material, the 9400’s transmitter equalizer can usually improve this
situation considerably.
Note that if you set the processing up for asymmetrical modulation
(which is done by editing the active Transmission Preset) and you observe
negative peaks that are higher than positive peaks, you can correct this
by changing the setting of the POLARITY control, located next to the AOX
100% or DOX 100% control.