Specifications

EAW Smaart 6 Operation Manual Analysis Modes and Display Types
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The Coherence Trace
The Coherence trace displays as a second trace in red in the upper portion of the fre-
quency/magnitude response plot if the Show Coherence Trace checkbox is selected in
the Frequency Response tab of the Options dialog.
The Coherence trace is normally plotted in the upper half of the Magnitude display using
the center line as zero and the top of the graph as its maximum value (100% = perfect
coherence). As the mouse tracking cursor moves across the plot area, the coherence values
for the current data point is displayed in red in the cursor readout above the plot.
Coherence Blanking
Coherence Blanking is a technique of not looking at data whose coherence is too low.
Coherence Blanking is similar to Magnitude Thresholding (see below) but works on
coherence value rather than signal strength. The Coherence Blanking parameters are in
the Frequency Response tab of the Options dialog (Figure 3-8).
Three parameters control Coherence Blanking:
Solid Above: The Coherence trace is drawn with a solid red line if the Coherence value
is above the level set here. This value defaults to 80%, which would be considered a
very reliable Coherence value for an acoustical measurement under ideal circumstances.
Invisible Below: The Coherence trace is not drawn if the Coherence value is below the
value set here. This value defaults to 10% and would only rarely require a lower value.
Transparent in between with minimum opacity: Frequency Response (Magnitude
and Phase) traces are drawn with variable transparency, based on coherence, where
higher values are more opaque and lower values are more transparent. The minimum
opacity value ensures data traces remain clearly visible all the way down to the mini-
mum acceptable coherence value (the Invisible Below threshold). The default for this
minimum opacity value is 30%. Under difficult viewing conditions, you may want to
set it higher to make low-coherence data more visible. Setting it to 100 effectively
disables coherence blanking.
Figure 3-8 Coherence Blanking parameters in Frequency Response tab of Options dialog