User guide Owner's manual

User manual for the ZEN 3-channel X-LMS controller Soft dB inc.
An estimate of the attenuation (or noise reduction) is presented in the upper right corner.
Overall attenuation can be displayed for all channels (an average is done) or for a
selected channel following the state of the control Att. type and Show filter Wx. The
following equation is used to provide an instantaneous estimate of the attenuation:












⋅=
∑
∑
256
1
2
256
1
2
10.
.
10.
Re clean
LogAtt
f
Error
inst
This calculation indicates the global noise reduction at the error sensors in comparison
with the reference sensors (after subtracting the contribution of the control sources).
Based on the input gain and the dynamic on both error and reference sensors, this
estimate may differ from the real attenuation.
The best indicator of control performance is the comparison of the global energy with and
without control at the error sensors. For an acoustic system, ideally the ultimate indicator
of control performance is the comparison of the average sound level with and without
control around the primary source.
The control interface includes a tool to measure the average power spectrum of all signals
in the system. The results of the measurement are shown on the lower graph of the main
interface. This tool is very useful for measuring the average attenuation with and without
control at the error sensors. Here is the measurement procedure:
1) While the control is active, select a linear average (Ave. type control in
the lower left corner) and a number of averages of 50 (Nbr. ave.
control).
2) Select the desired error signal using the Show Signal control.
3) Launch the average using the Start control and wait for the end of the
average (see the indicator Average completed)
4) Save the result using the Export Graph function. The exported file is a
text file in a format compatible with a program like Excel. The file
includes the average spectrum and the last instant time block (4196
samples).
5) Click the CONTROL PAUSE button and start a new average. Repeat
steps #3 and #4.
Here is the list of all selectable signals with the Show Signal control:
Signal Description
Rx Reference signals without the subtraction of control source
contribution
Ex Error signals
Cx Control outputs
ZEN User Manual p. 31