OBW Tab (Markers)

The OBW tab of the Markers dialog box provides the OBW marker control and configuration properties. This tab contains the parameters to setup and perform an occupied bandwidth or X dB bandwidth measurement. The OBW tab also provides the Centroid -> Center Frequency function.

The OBW marker only applies to spectrum traces.

The OBW tab includes these properties and functions:

Trace - at the top of the OBW tab is a dropdown box for selecting the trace on which to enable the OBW marker.

OBW - The OBD checkbox controls the state of the occupied bandwidth marker function. See About OBW Marker for more information.

Selected: Enables the OBW marker function and begins the occupied bandwidth and X dB Bandwidth measurements for the active trace (spectrum data only). See Making an OBW/BW Measurement for an example.

Cleared (default): Disables the OBW marker function for the active trace.

% Power - (default: 99%) specifies the percentage of total power in the measurement frequency span to capture with the OBW marker. A value of 100% will cause the entire frequency span to be captured by the OBW marker.

See the Measurement Algorithm section of the About OBW Marker topic for more information about how OBW is calculated.

Default: 99%

Range: 0% to 100%
X dB Bandwidth Threshold: sets the threshold in dB relative to the power of the highest level bin in the spectrum to use as a threshold for determining the bandwidth.

Default: -3.01 dB
Region Shown - sets the method used to determine the region shown in the selected spectrum trace and the Markers Window. Only one can be shown on a Spectrum trace at a time. However, you can create two Spectrum traces showing OBW on one trace and BW on the other trace. See Making an OBW/BW Measurement for an example.

Occupied Bandwidth: the signal's calculated occupied bandwidth is used for the region (labeled as "OBW") in the selected spectrum trace. Occupied bandwidth is based on the total power of the signal.

X dB Bandwidth: the signal's calculated X dB bandwidth is used for the region (labeled as "BW") in the selected spectrum trace. X dB bandwidth is based on the peak power of the signal.

Default: Occupied Bandwidth
Centroid -> Center Frequency: automatically sets the VSA center frequency to the centroid frequency calculated by the OBW marker. The centroid frequency is the midpoint frequency of the measured occupied bandwidth as calculated by the OBW marker. See the Measurement Method section of the About OBW Marker topic.