Keysight N9927-90001 User’s Guide                                                            249
IQ Analyzer (IQA) – Option 351 (CPU2 Only)
I/Q Analyzer (IQA) Mode Settings
refresh rate when the acquisition time is long. Changing the Stop 
Time changes which data point is displayed on the right side of the 
screen.
Couplings: When the change of Stop Time makes time domain 
display length exceed the limitation, the Start Time will change to 
satisfy time domain display length limitation:
——The maximum value is determined by current Sample Rate and 
the maximum capture samples.
——Stop Time is adjusted to the nearest sample point based on the 
Sample Period.
——The maximum time domain display length is 524,288 points.
Time Domain Display Length [pts] = {[Sample 
Rate[pts/s] x (Stop Time[s] - Start Time[s])] + 
1}
Where:
pts = points
s = seconds 
— Trigger Settings
 Opens the Trigger Settings softkey menu.
Then:
——Trig Type
 Then select one of the following:
Softkey Description
Free Run 
(Default.) – Triggering is provided by the FieldFox internal 
circuitry. A new acquisition begins when the previous 
acquisition ends.
External
An acquisition is triggered on an external TTL signal at the 
Ref In/Trig In connector on the FieldFox top panel. 
Choose to trigger on the rising slope at about 1.7 V or on 
the falling slope at about 1.0 V using the Trigger Slope 
setting (below).
Video 
An acquisition is initiated when the displayed amplitude 
of an incoming signal crosses the settable Trigger Level. 
This selection can detect low-amplitude signals, but also 
has been filtered considerably and may not be a true 
representation of the incoming signal. 
RF Burst 
An acquisition is initiated when the signal at the third IF 
(analog) stage crosses the settable Trigger Level. This 
selection offers a wider bandwidth and may be a better 
representation of the incoming signal than Video trigger. 
However, RF Burst is not as sensitive to triggering on 
low-level signals.