Chapter 2 209
One-Button Measurement Functions
SPAN X Scale (Spectrum Emissions Mask—SEM)
One-Button Measurement Functions
2.22 SPAN X Scale (Spectrum Emissions Mask—SEM)
Activates the Span function for the SEM measurement and displays the menu of span
functions.
Key Path: Front-panel key
State Saved: Saved in Instrument State
Remote Command:
See the Scale/Div, Ref Value, and Ref Position commands below.

2.22.1 Scale/Div

Allows you to enter a numeric value to change the horizontal display sensitivity by setting
the frequency units per horizontal graticule division. To determine full display frequency
span, multiply the frequency span per horizontal graticule division by 10. This function is
only available when you select Spectrum Emissions Mask from the Measurement menu.
Key Path: MEASURE, Spectrum Emission Mask, SPAN X Scale
State Saved: Saved in Instrument State
Factory Preset: 2.50000000 MHz
History: Added with PSA firmware revision A.02.00

2.22.2 Ref Value

Press Ref Value to set the frequency represented by the selected horizontal graticule line on
the display (the reference). The current value is indicated by Ref Value in the upper left
corner of the display. You can change the reference value using the step keys, the knob, or
the numeric keypad. You can set the reference line location using the RefPosition setting.
This function is only available when you select Spectrum Emissions Mask from the
Measurement menu.
Key Path: MEASURE, Spectrum Emission Mask, SPAN X Scale
State Saved: Saved in Instrument State
Factory Preset: Center frequency value in Factory Preset state.
History: Added with PSA firmware revision A.02.00

2.22.3 Ref Position

Press Ref Position to position the X-Scale reference to the extreme left line, center line, or