About 3D Trace Mapping

Three-dimensional trace mappings provide ways to analyze data over multiple measurement sweeps. This is done by storing trace data from multiple measurement sweeps and providing a way of viewing them together in order to make certain characteristics of a signal apparent that would not otherwise be apparent by looking at a single trace or a sequence of single traces one after the other.

There are three available types 3D mappings, as follows:

Spectrogram - shows a running history of traces from each measurement sweep with magnitude mapped to color
Digital Persistence - shows a set of traces drawn on top of each other with the age of a trace mapped to color intensity
Cumulative History - shows all traces since measurement restart. Color for each point on the display indicates how often the point was part of a trace line.

The 3D mapping types are not three-dimensional in the sense of using two dimensions to produce the illusion of a three dimensional drawing. Instead the 3D mapping types show a two dimensional plot of the data and use color to represent the third dimension.

The following sections contain information that is pertinent to some or all 3D mapping types.

Actions that clear the display

The following actions clear the trace buffer and restart the 3D mapping display:

Restarting a measurement
Enabling or disabling averaging
Selecting new measurement data
Changing any of the following:
- the average type
- number of points in the measurement data
- center frequency or span
- resolution bandwidth
- window type
- buffer depth of the spectrogram
- spectrogram height
- overlap percentage

Note that changing the Trace Format (coordinates), X Scale, or Y Scale does not clear the buffer.

Supported trace data

3D mapping displays support all trace data types except summary tables and symbol tables.

Time stamps

When 3D mapping is applied to a trace, each time the trace receives new information (trace scan) from a measurement sweep, the 3D mapping display is updated normally, except when the scan contains the same time stamp as the previous scan.

For Spectrogram, when a scan is received with the same time stamp as the last scan, the new scan replaces the old scan and the spectrogram does not scroll. For Digital Persistance and Cumulative History, scans with the same time stamp as the previous do not cause the display to update.

The following types of trace data have fixed time stamps:

Data registers
Math functions where the time stamp of leftmost data operand does not change each measurement sweep, even though the result of the math function may change with every measurement sweep.