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Linear Acoustic AERO.one User Guide
3.6.4
Audience Measurement Systems
Audience measurement systems such as the ones available from Nielsen (via Norpak) per-
form their functions by inserting a watermark into the audio signal. Careful testing by
Nielsen and Linear Acoustic has shown that the watermark signal is not disturbed by any
of the AERO factory presets or upmixing, and that locating the processor before or after
the watermarking equipment has no impact on audience measurement reliability.
In order to minimize any chance of audibly unmasking the watermarking signal, Linear
Acoustic and Nielsen recommend that where possible, watermarking equipment be in-
stalled after any audio processing equipment. However, audible unmasking is highly unlike-
ly with standard presets. This arrangement is not possible when the Dolby Digital (AC-3)
encoder is included in the processor, and so the watermarking equipment must be installed
prior to the AERO unit. This is completely acceptable and in use by many stations.
3.6.5
Emergency Alert Systems (EAS)
As EAS systems rely on passing data modulated as audio through the audio channels of a
broadcast facility, it is important to ensure that the path is capable of preserving this mod-
ulation. Ideally, EAS systems should be inserted after audio processing equipment and this
is how the EAS Input of the AERO.one unit is configured. Main audio is muted and ex-
ternally supplied EAS programming is inserted into the Left and Right output channels
post processing.
As shown below, EAS mode is active when the top menu shows "EAS" to the left of the
last two input meters. When not in EAS mode, this area will be blank, although the input
meters will still show activity of applied audio.
Figure 3-5 Main Menu showing EAS mode active
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Applications
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