Spectrum Analyzer Measurements : Occupied Bandwidth
Occupied Bandwidth
Occupied Bandwidth (OBW) measurements are set up using the SETUP Menu (Occupied BW).
OBW is a common measurement performed on radio transmitters. This measurement calculates the bandwidth containing the total integrated power occupied in a given signal bandwidth. There are two different methods of calculation depending on the technique used to modulate the carrier.
% Integrated Power Method: The occupied frequency bandwidth is calculated as the bandwidth containing the specified percentage of the transmitted power.
> dBc Method: The occupied frequency bandwidth is defined as the bandwidth between the upper and lower frequency points at which the signal level is a desired number of dB below the peak carrier level.
Occupied Bandwidth Measurement
1. Occupied bandwidth measurement results are shown in a table at the bottom of the display.
2. Dashed vertical lines and a shaded region define the main channel.
3. All occupied bandwidth measurement parameters are set via the SETUP menu.
Frequency and span settings for many signal standards can be set as follows:
1. Press MEASURE on the main menu.
2. Select OBW from the MEASUREMENT button.
3. Press SETUP and then do the following:
Set the % OBW power or set X DB (dBc) power value
Select the METHOD (Percent (%) or dBc (X DB)
Toggle OBW limit testing if you wish to see pass/fail test results
Occupied bandwidth is a constant measurement; after it is turned on, it remains on until a different measurement is selected or the sweep is paused. OBW is calculated at the end of each sweep.
SETUP Menu (Occupied BW)
The occupied bandwidth SETUP menu is available in MEASURE > MEASUREMENT > OBW > SETUP. After the OBW measurement is selected, the SETUP menu can be quickly accessed by tapping on the summary display area below the spectrum display.
SETUP Menu (Occupied BW)

Sets the percentage of the total power that is measured within the occupied bandwidth for the current measurement. The resulting occupied bandwidth and total power values are displayed in the measurements results table.
X dB
Sets the x dB value used for the "x dB bandwidth" measurement. The occupied bandwidth is the frequency range between two points on the signal that are x dB down from the highest signal point within the OBW span.
Enables limit checking at the specified frequency. The limit test results show as a green PASS or a red FAIL in the measurement table.
Select the measurement method to be PERCENT (%) or X (dB).
Sets all OBW setup parameters to default. Turns off limits.