Orban OPTIMOD-FM 8600Si, Руководство по эксплуатации

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2-38
INSTALLATION ORBAN MODEL
the
1770 L
OUDNESS
T
HRESH control. In an overshoot-free transmission sys-
tem, a 1 kHz sinewave at –23 LUFS must produce an FM carrier deviation
of
±
10 kHz without pilot tone. This corresponds to 13.33% modulation
without pilot tone. This calibration includes 50
µ
s transmission preempha-
sis.
Note for version 2.0 software : We have found that with typical pop
music, a –23 LUFS setting typically produces about –5 dB BS.412 MPX
Power and rarely produces ±75 kHz peak carrier deviation. 0dB MPX
power is not reached unless the
BS.1770 T
HRESHOLD
control is set to ap-
proximately –17 LUFS. This behavior seems odd (the low modulation level
significantly compromises the received S/N ratio in weak signal areas and
in moving vehicles), so we are unsure if our interpretation of EBU Tech
3344 is correct in this initial release and we welcome any feedback. Please
email Bob Orban at the address shown if you discover an error in our calibration.
D) The calibration of the
1770 L
OUDNESS
T
HRESH control is correct if the transmit-
ter’s modulation level was calibrated using your Optimod’s built-in lineup
tone (step 11.D) on page 2-19). If you turned down the drive level to the FM
transmitter (via the
C
OMPOSITE
O
UT
, DO 100%,
or
AO 100%
controls depending
on how you are driving your transmitter) to compensate for overshoots in the
signal path following the Optimod, turn the
1770 L
OUDNESS
T
HRESH control up
by the same amount that you turned the output level control down. This will
preserve correct loudness at the receiver.
For example, assume that you turned down the output level control by
2 dB compared to its calibration using your Optimod’s tone generator, so
that a line-up tone that would produce
±
75 kHz deviation in an over-
shoot-free transmission system instead produces
±
59.6 kHz deviation to
allow for 2 dB of overshoot with program material. In this case, set the
1770 L
OUDNESS
T
HRESH control to –21 LUFS instead of –23 LUFS.
E) If you have not already done so in step 1 on page 2-23, activate the MPX Pow-
er Controller by setting it to some setting other than
O
FF
. This is necessary to
enable the
M
ULTIPLEX
P
OWER
O
FFSET
control.
Using program material typical of your format, adjust the
M
ULTIPLEX
P
OWER
O
FFSET
control so that the BS.1770 Safety Limiter produces about
3 dB of gain reduction on typical program material. This control is part of
the processing preset, so after you have set the control, save the preset as
a User Preset.
You must adjust the
M
ULTIPLEX
P
OWER
O
FFSET
control for each processing
preset you plan to use and then save each one as a user preset.
14. End Analog and Digital I/O setup.
If you are using an external AGC and you temporarily set the
E
XT
AGC
to
NO
in
step 1 on page 2-26, set the
E
XT
AGC
to
Y
ES
.
15. Select a processing preset.
See step 13 on page 2-22.