Meyer Sound SIM 3 User's Guide download pdf (Page 152)

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CHAPTER 7

Using SIM 3

7.5.3. Setting the Coherence Threshold

Coherence Threshold percentages from 90% to 0% can be set within the Frequency

Response measurement. Use the drop-down box at the bottom of the measurement

window, or open the Frequency Response Settings dialog box by right-clicking within the

measurement window or selecting it from the Settings menu.

Setting the number of averages (Avs) automatically sets the coherence threshold to a certain

percentage:

Averages (Avs) Coherence Threshold

2 90%

4 60%

8 40%

16 20%

NOTE: For example, a 90% Coherence Threshold means that the

correspondence between the measured signal at the two measurement points

must be extremely high in order for SIM 3 to produce a trace in the graph view for

that frequency; at lower levels of coherence it will be blanked. This methodology, and

the relationship of the number of averages with the coherence percentage shown

above, prevents SIM 3 from presenting trace data for frequencies that might be

erroneous.

7.5.4. Adjusting the Coherence Trace

The position of the coherence trace in the graph can be adjusted via the [+] and [–] buttons

on the right side of the Frequency Response window to three views: the entire window, the

top half of the window, or the top third of the window. The scale, showing values of 0, 50,

and 100 percent, is also presented on the right side of the window.

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Meyer Sound SIM 3 User's Guide Page 152