Installation guide

VAR4 / VAR12 / VAR20 - Product Description
3.9.1.2 Volume Control Operation
The application of the Volume Control function is to allow remote control of the volume of specific input
sources within a specific zone or zones. Normally the volume control will be mounted within the zone and
allow the control of the specific sources, such as background music sources, while leaving the volume of all
other sources unaffected.
It is possible to assign a particular Volume Control to be associated with one, or any group of, VAR Router
outputs. It is then possible to assign which input, or group of inputs, are controlled.
Each step of the volume control gives exactly 3dB attenuation, with position ‘1’ being ‘off’.
The connection between the Remote I/O Unit and the Volume Control is monitored, so that open and short
conditions on the cabling are detected and logged by the VAR Router. The VAR Router fault report identifies
the specific Remote I/O Unit and the particular analogue channel number affected.
In the event of such a fault, the volume will default to that set up on position ‘off’, i.e. the maximum level.
The same default operation occurs in the event of RS485 communications failure to the Remote I/O Unit.
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Only one Volume Control should be configured to govern an input in respect of a single output.
If two Volume Controls are configured to govern the same input in respect of an output, then the
results are unpredictable.
3.9.1.3 Ambient Noise Sensor (ANS)
The purpose of an ANS system is to adjust the level of public address announcements based on a measure
of the ambient noise in the target zone. This is intended to maintain a set volume of public address audio
above the ambient noise, in order to guarantee that the announcement is intelligible, yet at a comfortable
level.
The ANS sensor (ASL ANS01, ANS02, ANS03, or ANS04) is an analogue device that produces a DC
voltage proportional to the measured ambient noise level.
The DC voltage is received via the Remote I/O Unit analogue channel, and is translated to a value of
measured ambient noise in dBA. This value is used to proportionally adjust the VAR Router output gain for
the configured output channels.
The VAR Router is set up for the maximum broadcast volume without the ANS, and the ANS system then
reduces the gain from this level when the zone is quiet.
In the ANS setup, a minimum threshold value of ambient noise (in dBA) is programmable to each output.
This is used to limit the range over which the gain may be reduced. When the ambient noise reaches or is
below this value, the Router applies the maximum reduction to the output gain. Therefore this has the
minimum gain, and a lower ambient noise will not reduce the broadcast volume further.
A maximum threshold value of ambient noise (in dBA) in the zone is also programmable to each output.
When the ambient noise reaches or exceeds this value, the Router applies the full configured output gain for
the zone.
A software configurable ‘Attack Time’ is programmable for each output channel. The Attack Time controls the
rate at which the Router can increase the gain when the ambient noise rises. This is to stop the ANS system
from suddenly increasing the broadcast volume in response to any short-term increases in ambient noise.
It is possible to configure a particular ANS sensor to control one, or any group of, VAR Router outputs, and it
is possible for more than one ANS sensor to be used to control the gain in a single zone.
It is possible to assign up to 12 ANS sensors to a single VAR Router output (provided that the
sensors are connected to the same BMB01 Remote I/O Unit). Where this is done, the highest of
the received ANS values is used, i.e. the maximum volume required by any to the ANS sensors
is used.
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Issue: 03 complete, approved
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