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Automatic Gain Control (AGC) and Noise Cancellation (NC) are also provided per AEC
algorithm. AGC ensures that microphone levels remain at an optimum level, and NC
removes steady state noise (such as from a projector fan or air conditioning device) from
the signal path.
Non-Linear Processing (NLP) dynamically adjusts to minimize echo caused by under or
over-cancellation.
CONTROL INPUTS
Used to connect switches or potentiometers, e.g. BLU-3 selector wallplate (Part no.
Z-BLU-3). Looking at the control port connector (on the back of the unit), there are two
common (ground) connections C to the left of the twelve CONTROL INPUTS and, two
software assignable reference voltage outputs R to the right.
The control ports have two modes of operation: 2-wire and 3-wire.
2-wire mode
In this mode the twelve CONTROL INPUTS are internally ‘pulled up’ to +5V DC via
a 4.7kOhm resistor. Therefore, no external voltage source is needed to create contact
closure to ground for switches such as mute buttons or, resistance to ground (for other
multi-state or continuous controls such as Parameter Presets or faders).
See the help file within HiQnet London Architect for a table of resistor values for use with
Parameter Presets or source selectors.
Two ‘common’ ground connections are provided using the two C connectors to the left of
the CONTROL INPUTS.
A 47kOhm-log potentiometer (Part no. DM10018) connected between a control input
and common will allow parameters to be controlled linearly.
3-wire mode
This mode allows the use of linear pots or faders for continuous controls. A pot would be
wired as a potential divider with the top of the track connected to the reference output
R, the wiper to a control input and the bottom of the track to a common C. For good
performance, pots with track resistance between 10K and 100KOhms are recommended.
LOGIC OUTPUTS
Used to connect ‘tally’ indicator LED’s or relays.
There are six standard LOGIC OUTPUTS which produce 0V or +5V DC via an internal
440 Ohm resistor and two internally connected common (ground) connections C.
An LED connected between one output (Anode, A) and common (Cathode, K) will
illuminate when the LOGIC OUTPUT is activated, without requiring any external current
limiting resistor.
A high sensitivity relay (such as a reed relay) may be driven by connecting four outputs in
parallel. This arrangement will develop 4V across a 500-Ohm coil, providing that all four
outputs are made logic 1 simultaneously.
