Tektronix RSA6100A Series, Help Manual

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RF Measurements > Settling Time Measurements Settling Time Measurement Overview
The instantaneous phase is computed as:
The instantaneous frequency is the derivative of the phase:
Data smoothing is applied (if selected by the user). This
fi ltering method uses ±n adjacent samples to
produce an average value that is used to replace the values of the original 2n samples. An example
is shown below.
If averaging is turned on, the smoothed data array is averaged with data arrays of previous acquisitions on
a point-by-point basis. Smoothing has the advantage of reducing noise-like variations in the measurement,
but carries the risk of masking real measurement data. The amount of smoothing applied must be
determined by evaluating the waveform you see for artifacts that result from the process.
Next, Settled Frequency is calculated. Settled frequency is the average frequency determined by looking
back in time from the point set by the Measurement Length control over a minimum of 256 samples. This
value is used to determine the frequency level about which to center the Tolerance range. The measurement
then searches backward through the data until it
fi nds the fi rst point that exceeds the tolerance range. A
maximum of 20 million acquisition data samples can be processed by the measurement.
Settling Time is measured as the time from the start reference to the point where the frequency remains
within the tolerance band. The start reference can be any of three points:
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RSA6100A Series Real-Time Spectrum Analyzers Help