RTW DigitalMonitor 10500X-PLUS, Operating Manual

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RTW DigitalMonitor 10500X-PLUS 168
E 4.2.1 Background: The ITU BS.1771 Loudness Measurement
A reliable and standardised method for evaluating program loudness is es-
sential for all audio and video work – for example to make it possible to
normalise the sound in production to prevent unpleasant jumps in volume
on switching between different program sections in radio and TV broadcasts.
The DigitalMonitor 10500X-PLUS has an integrated loudness measurement
function conforming to the ITU BS.1771 recommendations for stereo sound
signals, which can be displayed as an alternative to the standard PPM peak
program meter bargraph display. Presets enable the user to switch between
the two modes at any time. Switching from PPM mode to the ITU BS.1771
mode activates the ITU loudness display scale, which uses dB LU (dB
Loudness Units) in a range from –21 to +9 or LKFS in a range from –31 to
0. Depending on the channel mode the display two bars for the individual
loudness, plus two additional bars as defined in the „ITU-Bar“ selection of
the the ITU BS.1771 panel.
• Momentary „M“:
The M bar display shows the momentary sum loudness for all the con-
nected channels for a preset period, using the ITU BS.1770 RLB filter.
The dynamic range of this bar scale is the same as those of the individual
channels.
• Integrated „I“:
The I bar display shows the mean momentary value for an ongoing time
window (e. g. for the last 20 s). This integrated display with a dynamic
time window is not falsified by pauses in the signal because signals below
a user-adjustable threshold do not influence the display. Depending on
the time setting, this bar display may appear rather slow or even static.
Using a configuration setting it is also possible to display the integrated
level value numerically in Multi Instrument 2 (see Fig. E 4-20).
• Longterm „L“:
The L bar display shows an infinite or manually control longterm loudness
value. This display is not falsified by pauses in the signal because signals
below a user-adjustable threshold do not influence the display. This bar
display may appear rather static. Using a configuration setting it is also
possible to display the longterm loudness value numerically in Multi In-
strument 2 (see Fig. E 4-20, shown is the integrated value).
E 4 Display Modes • E 4.2. Program Meter: ITU BS.1771 mode
(Loudness)