User manual

Audio Analyzer
4-70
AM700 Audio Measurement Set User Manual
Resolution. This setting is in units appropriate to the measurement being made. The
resolution setting is the absolute difference of a data point value that is considered
settled. The default settings for resolution for a measurement are the measurement
resolution of the AM700 and can be used in many instances. Tolerance and the
Resolution act together across the measurements range. At the low end of the
measurement range, where the noise level has more influence on the measurement,
the Resolution setting will determine if a data point value has settled; at the high
end of the range, the Tolerance setting is used to determine if a data point is settled.
There is a usually a crossover region when Tolerance (percentage of a measurement
data point value) and Resolution (absolute difference) will produce the same result
for determining that a data point has settled.
Variation. In XY mode the Audio Analyzer restarts settling when the acquired data is
outside of the limit you specify in the Variation section of the Settled Data Point
Detection Controls display. The Variation setting is in percentage of difference
between a settled data point and the incoming data that is permitted before settling
is restarted. This value is chosen to prevent small changes in a data point value, as
might be seen with accompanying noise, from being seen as a new value.
Variation Type. This selection is used to determine which parameter or parameters
are to be checked for variation. The setting choice of Either looks at either
measurement axis (X or Y) and restarts settling when a value outside of the
Variation setting for either axis is detected. The Both selection is used to detect
when the incoming data values are outside the Variation setting in both axes. The
two other choices, Dependent and Independent, are used to select either axis of a
measurement to check while ignoring the other. The Dependent axis is the Y-axis
and the Independent axis is the X-axis. These choices would be used, for example,
when you want to check for amplitude variations while running a fixed frequency or
to check for frequency variations when running a fixed amplitude signal.
In the Audio Analyzer application, a measurement trace can be displayed with
respect to a reference. When the front-panel Set Ref is pressed, a reference is stored
in memory for immediate use (see Figure 4-30). To use a reference for comparison it
must contain valid data and be appropriate for the measurement. For example, a
THD+N measurement cannot be used as a reference for a Level versus Frequency
measurement. If the reference selected, either from memory or from a file, is not
appropriate or does not have valid data, the “reference available” label is removed
from the display.
Relative to
Reference
Controls