Keysight N9915-90020 User’s Guide 337
Electromagnetic Interference (EMI) Measurements – Option 361
EMI Measurements Mode Settings
— But, when using Fast SA Scan, you have a standard 3 dB resolution
bandwidth over the entire range of 1 Hz to 5 MHz.
Learn more, see
Chapter 9 and then “Resolution Bandwidth (Res BW)” on
page 187
.
Single / Continuous / Restart
This setting determines whether the FieldFox measures continuously or only
once each time the
Single or Run / Hold +/- button is pressed. Use Hold /
Single or to conserve battery power or to allow you to save or analyze a
specific trace.
How to set Single or Continuous
—Press Sweep 3
.
— Then choose one of the following:
—
Continuous
——ON Causes the EMI to make continuous sweeps. This is the
typical setting for making measurements. Each Run / Hold +/-
press causes the SA to toggle between continuous sweep and
Hold.
——OFF Causes the EMI to Hold. Each Run / Hold +/- or Single
press causes the SA to make ONE sweep, then Hold. The Hold
annotation changes to an arrow --> while the sweep occurs.
—
Single Automatically sets Continuous OFF and causes the SA to
make ONE sweep, then Hold.
— Restart Resets the Average counter to 1. The Average counter also is
used with MaxHold and MinHold Trace States. Learn more in
“” on
page 340
.
c. The 75001 point limit is put in place, to keep the mode from trying to build traces that are any bigger than neces-
sary. Basically, enough to cover CISPR Band E (1 GHz to 18 GHz) with its 1 MHz bandwidth, plus a little extra mar-
gin. This same point limit (75001) is applied to the other resolution bandwidths (Res BW), and also to the other
CISPR Band Scan Maximum Span Values (displayed in the third column). There is no direct control permit-
ted over the number of points used in the EMI scans. But, indirectly the SPAN and resolution bandwidth (Res BW)
values, determine the number of points.
Exception: When using Fast SA Scan measurement (displayed in the fourth column), then you can control the
number of points, similar to SA mode, where the point limit then becomes 20001.
d. The Zoom scan span limits are associated with the EMI 6 dB Resolution Bandwidth(s) (Res BW (6 dB)) that
are (displayed in the second column). The auto-coupled bandwidth choices match those CISPR Bands (displayed
in the first column), but you can also choose to manual couple (Manual) the bandwidth. When the bandwidth is
set to manual couple (Manual), the Zoom scan span limit follows the resolution bandwidth (Res BW), not the
CISPR band.
e. The Zoom scan span limits are actually the width of the FFT that is being used for the EMI 6 dB Resolution
Bandwidth (minimum == 1 FFT, so the span is limited to 1 FFT width).
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