1265
Span
Zero Span
Changes the displayed frequency span to 0 Hz. The horizontal axis changes to time rather than
frequency. The amplitude displayed is the input signal level at the current center frequency. This is a
time-domain mode that changes several measurement functions and couplings. The test set behavior is
similar to an oscilloscope with a frequency selective detector installed in front of the oscilloscope. See
Application Note 150 for more information on how to use zero span.
You can enter Zero Span in several ways:
Press the Zero Span key in Span
Set Span = 0 Hz
Press last Span if the last span was 0
You cannot go to Zero Span by setting start freq = stop freq, or rolling span down with the RPG , that will
limit you to 10 Hz
You can go back to Swept Span by setting Span to a nonzero value or pressing Last Span, assuming the
last span was not also zero span.
Pressing Zero Span places the test set in Center/Span frequency entry mode.
The following table summarizes the differences between Zero Span and Swept Spans:
Example FREQ:SPAN:FULL sets the span to full frequency range of the test set
Notes n /a
Couplings Turns off signal tracking (span zoom). It does NOT turn off the markers, nor
the current active function.
Initial S/W Revision Prior to A.02.00
Zero Span Swept Spans
X axis is time X axis is frequency
There is no auto-RBW selection unless the EMC
Standard is CISPR or MIL RBW coupled to Span when RBW in auto
There is no auto sweep time Sweep time coupled to RBW when sweep time in
auto
Interval Power calculated in Mkr Function Band Power calculated in Mkr Function
Can only define time limits when in zero span Can only define frequency limits when in swept
spectrum analysis
Marker Count counts at the center frequency Marker Count counts at the marker frequency
CF Step Size set to RBW value CF Step auto couples to 10% of Span
Some “Marker ->” commands not available. Other “Marker ->” commands not available
Freq entry mode always Center/Span Freq entry mode can be Center/Span or Start/Stop