Display Line; Noise Marker - Keysight N9912A User Manual

Display Line

A display line is a simple, horizontal line that can be placed at any amplitude level on
the SA screen. Use a display line as mental guide for visual feedback. A display line is
similar to a Limit Line, except that no PASS/FAIL testing occurs. A display line is
easier to create than a Limit Line. Learn about Limit lines on page 156.
How to create and move a Display Line
 Press Limit __8
 Then
 Then enter a Y-axis value using the ▲|▼ arrows or the rotary knob, then press

Noise Marker

For comparison purposes, electronic noise measurements are often displayed as
though the measurement was made in a 1 Hz Res BW. However, making an actual
measurement at a 1 Hz Res BW is impossible, and at 10 Hz, extremely slow.
A Noise Marker, unique to SA Mode, mathematically calculates the noise
measurement as though it were made using a 1 Hz bandwidth.
Several data points (or 'buckets') are averaged together to calculate the Noise
Marker readout. To accurately measure noise, the Noise Marker should NOT be
placed on, or too close to, a signal. The distance from a signal depends on several
factors. To know if an accurate reading is being made, move the Noise Marker until
consistent measurements are displayed in adjacent data points.
90
[NPk] Displays the minimum value of all the measurements in
Negative Peak
o
each bucket.
[Smp] Displays the center measurement of all the measurements in
Sample
o
each bucket. This setting gives a good representation of the random noise in
each bucket. However, it does not ensure that all signals are represented.
[#RMS] Displays the Root Mean Squared (RMS) average power of all
Average
o
the measurements in each bucket. This is the preferred method when making
power measurements. Learn more on page 155.
Display Line OFF ON
Enter. Or enter a value using the numeric keypad and press a suffix key or press
Enter.
Display line with annotation
FieldFox User's Guide