Performing a Basic Occupied BW Measurement

NOTE: The E7495A/B defaults to Average (RMS) detection to measure the occupied bandwidth power. Average (RMS) detection gives the most accurate results, so the default detector setting should therefore be maintained for OBW measurements. Sample detection will give similar results to the Average (RMS) detection, although the results will be less repeatable. Peak and Negative Peak detection will give higher and lower results, respectively, from the actual power.

To reproduce repeatable power readings, use the default Average (RMS) detector. In addition, you should use Running Average or Group Average with 50 or more averages. For more details on averaging, see "Setting Average, Sweep, and Restart"

Step
 		Notes
1
 		Select Spectrum Analyzer.
  • Mode
  1. [Spectrum Analyzer/Tools]
  2. [Spectrum Analyzer]

2
 		Enter the channel standard.
  1. [Chan Std]
  2. Select the standard using the up and down arrow buttons.
  3. [Select]
  4. On [Units] select Chan.
Each time you press the [Units] menu key, the selected option changes.
3
 		Enter the channel number.
  1. [Channel]
  2. Enter the channel number using the numeric keypad.
  3. Select [Fwd] or [Rev].

4
 		Set the span.
  1. [Span]
  2. Enter the frequency using the numeric keypad.
  3. [Hz], [kHz], [MHz], or [GHz]
Refer to the note above.
Use [Setup] [Res BW] to ensure the RBW is set between Span/255 & Span/127.
5
 		Turn on Averaging.
  1. [Span]
  2. Enter the frequency using the numeric keypad.
  3. [Hz], [kHz], [MHz], or [GHz]
Use [Average/Sweep] to set Averaging ON, set to Running Average or Group Average, and set Average number to 50 or greater.
6
 		Connect to the base station.
7
 		For an over the air measurement, connect an antenna and an external filter to the RF input.
 		The external filter is necessary to eliminate out-of-band signals that would otherwise reduce the dynamic range of measurements in the band of interest. The effect of the out-of-band signals is to raise the noise floor, possibly hiding some or all of the signal of interest. However, the external filter is optional in this set up:
  • If you want to limit your search to a specific band of interest you should use it
  • If you want to search beyond a specific band then can leave the filter off.
8
 		Set the level to Autoscale.
  1. [Level]
  2. [Autoscale]

9
 		Select the Occupied BW Measurement.
  1. [Measurements]
  2. [Occupied BW]
  3. On [Occupied BW] select On.
A marker pair will appear on the trace and the occupied bandwidth value and the integrated power in the Occupied BW are displayed in the data window below the trace graticule.
10
 		Set the percentage of power for calculating the Occupied BW.
  1. [Power]
  2. Enter the percentage number using the numeric keypad.
  3. Select [%].
The default percentage is 99%.
11
 		If you are measuring a narrow signal such as TDMA or PDC, zoom in on the signal for a more accurate Occupied BW results.
  1. [Freq/Chan/Span]
  2. [Span]
  3. Enter the frequency using the numeric keypad.
  4. [Hz], [kHz], [MHz], or [GHz]