User manual

Audio Analyzer
AM700 Audio Measurement Set User Manual
4-69
NOTE. In Regulation mode, continuous rapid plotting of unsettled data points
typically means that the settled data criteria are not appropriate. Though it slows
data acquisition and display, making the settled data criteria more restrictive and
increasing the delay time usually eliminates this behavior. When the correct delay
time for a device under test is determined, it should be noted for future testing.
Timeout. The Timeout editor specifies how long the instrument will attempt to fit
incoming data into the defined tolerances. When the timeout expires, if a settled
data point is not defined, the data is considered to be unsettled and is displayed on
the trace as an open circle rather than a point. The generator can then progress to the
next output level, and a new data point settling time begins after the Delay Time has
elapsed. A time-out condition can occur when the tolerance setting is too tight for a
noisy signal.
Samples. This setting specifies the number of consecutive settled data samples that
are used to define a settled measurement. The specified number of consecutive
samples must fall within the tolerance or resolution you specify in the Tolerance and
Resolution boxes for a measurement, or they are not considered to be part of a
settled measurement and rejected. If the selected number of consecutive samples are
within the specified tolerance or resolution, they are used to determine that a data
point has settled.
Tolerance. The Tolerance setting is the percentage of difference between data point
values allowed to be considered as settled data. A data point value is checked
against the previous measurement samples to determine if it is within tolerance for
settling. The number of samples checked is set in the Samples editor. Tolerance
settings can be made for all of the Audio Analyzer measurements (Frequency,
Level, THD, THD+N, IMD, Level Diff, Phase Diff, Crosstalk, and Separation) as
needed for the measurements being made. For example, if measurement 1 is set to
Level Diff and measurement 2 is Phase Diff, only those Tolerance settings need be
considered if adjustments are needed to produce settled data.
Setting tolerance percentage for tight settling provides more accurate measurements
but will usually require longer generator dwell times and longer timeout settings to
avoid missing points. For very quiet instruments, the tolerance percentage can be
reduced well below the default setting for tolerance. When measuring noisy devices,
the tolerance percentage may have to be increased for testing purposes. The selected
Settling mode selection (Exponential or Flat) also affects the action of the Tolerance
setting.