Orban OPTIMOD-FM 8600Si, Руководство по эксплуатации

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OPTIMOD-FM DIGITAL INTRODUCTION
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into the composite signal in the analog domain, after it is metered. Therefore, you
must mentally add the subcarriers to the meter indication, or refer to an external,
calibrated modulation monitor.
BS.1770-3 Loudness Level
The subjective loudness meters, labeled
L
OUDNESS in the 8600Si PC Remote GUI, dis-
play the loudness at the output of the digital radio processing chain and analog FM
processing chains, measured by the ITU-R BS.1770-3
5 algorithm.
The loudness meter indicates both BS.1770 Short-Term and Integrated Loudness on
the same scale. The solid bar indicates the Integrated Loudness, while the floating
bar segment indicates the Short-Term Loudness. Per the BS.1770-3 specification, the
integration time of the Short-Term Meter is always 3 seconds, while the Integrated
Meter uses silence gating and its integration time is 10 seconds. Because the meter is
always monitoring program material, it integrates the previous 10 seconds of pro-
gram material and weights all program material equally within the specified time
window. For example, material occurring 3 seconds in the past and 8 seconds in the
past both contribute equally to the meter’s current indication; newer program mate-
rial in the specified time window is not favored over older program material.
Because loudness perception combines the contributions of all acoustic sources,
there is only one Loudness Level meter indication for both stereo channels.
The unit of measure in the BS.1770 meter is LKFS or LUKS, which are the same, dif-
fering only in nomenclature. A change of 1 LUFS is the same as a change of 1 dB.
In the digital radio chain, “LKFS” and “LUFS” are absolute loudness measurements
with respect to digital full scale. “LK” and “LU” (without the “FS”) are relative loud-
ness measurements, where “0” on the meter corresponds to a user-preset “BS.1770
Reference Level,” which you set via your Optimod’s
BS.1770 L
OUDNESS
C
ONTROL
T
HRESHOLD
control. The BS.1770 meter on your Optimod indicates “LK” or “LU”; you
can choose which label to use via a control available on the
HD D
IGITAL
R
ADIO
tab in
I/O
SETUP
. The other BS.1770-associated controls for digital radio are also there.
The meter is scaled so that the loudness level at the consumer’s receiver is correct
when the 8600’s digital radio processing chain is adjusted to make the dominant
program material indicate “0 dB” on the 8600’s Loudness Level meter and the
BS.1770 R
EFERENCE
L
EVEL
(which you must enter manually) in
I/O S
ETUP
> HD R
ADIO
is equal to that specified by the regulatory authority in your country.
In the analog radio processing chain, the BS.1770 meter and Safety Limiter are cali-
brated per EBU Tech 3344
6
, Section 5.9. This calls for a 1 kHz sinewave at –23 LUFS to
5
Recommendation ITU-R BS.1770-3 (08/2012): “Algorithms to measure audio pro-
gramme loudness and true-peak audio level.” BS.1770-3 first introduced gating to
the loudness meter. For further information about the BS.1770-3 meter, please refer
to the following standards: ITU-R BS.1770, ATSC A/85 EBU R 128, EBU Tech 3341, EBU
Tech 3342, EBU Tech 3343, and EBU Tech 3344. These are free downloads that can be
found easily with a search engine.