RTW SurroundMonitor 10600, Operating Manual

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RTW SurroundMonitor 10600 196
RTW SurroundMonitor 10660-VID
E 4.2.1 Background: The ITU BS.1771 Loudness Measurement
Function
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 SurroundMonitor 10600/10660-VID has an integrated loudness measure-
ment function conforming to the ITU BS.1771 recommendations for stereo
and 5.1 surround 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 has
either two or six bars for the sum loudness of the stereo or 5.1 surround
channels, plus two additional bars as defined in the „ITU-Bar“ selection of
the the ITU BS.1771 panel.
• M - Momentary:
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. In
5.1 surround mode you can also define weighting factors for the individual
channels for the sum calculation. The dynamic range of this bar scale is
the same as those of the individual channels.
• I - Integrated:
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 4-21).
• L - Longterm:
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 4-21).
E 4 Display Modes • E 4.2. ITU BS.1771 (Loudness-display)