User Manual

Chapter 2 95
Instrument Functions: A - L
Det/Demod
Instrument Functions: A - L
2.3 Det/Demod
Displays the menu keys that control parameters associated with the detector modes.
2.3.1 Detector
Select a specific type of detector, or choose Auto to let the instrument select the appropriate
detector for a particular measurement.
When discussing detectors, it is important to understand the concept of a trace “bucket.”
For every trace point displayed in swept and zero-span analysis, there is a finite time
during which the data for that point is collected. The analyzer has the ability to look at all
of the data collected during that time and present a single point of trace data based on the
detector mode. We call the interval during which the data for that trace point is being
collected, the “bucket.” Thus, a trace is more than a series of single points. It is actually a
series of trace “buckets.” The data may be sampled many times within each bucket.
In swept analysis, the time interval of data collection for a display bucket also represents a
frequency interval. In FFT analysis, the bucket represents just a frequency interval. The
detector determines the relationship between the spectrum computed by the FFT and the
single data point displayed for the bucket.
When the Detector choice is Auto, the detector selected depends on marker functions, trace
functions, and the trace averaging function.
See
“Auto Rules For Detector Selection” on page 97 for information on the Auto detector
selection.
When you manually selected a detector (instead of selecting
Auto), that detector is used
regardless of other analyzer settings.
The detector choices are:
• The Sample detector displays the instantaneous level of the signal at the center of the
bucket represented by each display point.
• The Normal detector displays the peak of CW-like signals and maximums and minimums
of noise-like signals.
• The Average detector displays the average of the signal within the bucket. The averaging
method depends upon Avg Type selection (voltage, power or log scales).
• The Peak detector displays the maximum of the signal within the bucket.
• The Negative Peak detector displays the minimum of the signal within the bucket.