LUCIA FUNCTIONS
Auto null
In order to null the unit, depress and hold the null control for a minimum of 3 seconds, upon release the
unit will start the null process. If the unit is in Clear-Com mode, channel 1 will be nulled taking
approximately 30 seconds. If the unit is in RTS mode channels 1 and 2 will be nulled consecutively taking
approximately 60 second. Whilst the null process is underway the front panel controls will be locked in
their current states until the null process is complete.
Nulling is the process where the Lucia automatically sets its party-line interface for you to achieve the
very best possible audio performance. When the null process is started Lucia sets the internal amplitude
and phase pots to zero, the noise source is switched on, then the amplitude pot is moved through each
of its 256 positions. At each position the returned signal level is measured and stored. These values are
then reordered from lowest to highest and the indexes of the 8 lowest values stored in a new array (see
column 1).
The first of these indexes is then written to the amplitude pot, the phase pot is then moved through
each of its 256 positions, and the returned signal level measured. The phase pot index that generated
the lowest signal level value is then stored as is the signal level value itself (see columns 2 and 3). This
process is then repeated for each of the 8 stored amplitude pot indexes.
The result is three 8 value arrays, an arbitrary example is shown below:
Table 1: Null array example
Amplitude pot index
Phase pot index
Phase pot index signal level
2
4
-60 dB
4
3
-61 dB
5
4
-60 dB
7
4
-63 dB
0
8
-59 dB
1
2
-60 dB
2
1
-56 dB
The combination of phase pot and amplitude pot indexes that give rise to the lowest signal level to are
then written to their respective pots and stored in non volatile memory.
***WARNING***
During the null process high level audio tone is sent to the party-line circuit. Make sure all
party-line headphone/ headset users have removed their headphones/ headsets prior to
nulling.
Mic kill
Mic kill signals are sent to the 2 Wire intercom units prior to the null process beginning. When the LUCIA
unit set to interface between Dante and Clear-Com units this is achieved by toggling the power on pin 2.
When set to interface between Dante and RTS units this is achieved by transmitting 24 kHz tones on pins
2 and 3.
