HP ESA-L1500A User's And Calibration Manual page 42

Spectrum analyzers with Option 1DP default to display amplitude
NOTE
values in dBmV when in a log scale mode.
Figure 2-4 Relationship between Frequency and Amplitude
7. Set the marker.
Chapter 2
If desired, use the reference level function to place the signal peak at
the top of the screen using the knob, step keys, or numeric keypad.
(Marker functions measure the frequency and amplitude of a signal.)
Figure 2-4 demonstrates the relationship between center frequency
and reference level. The box in the figure represents the spectrum
analyzer display. Changing the center frequency changes the
horizontal placement of the signal on the display. Changing the
reference level changes the vertical placement of the signal on the
display. Increasing the span increases the frequency range that
appears horizontally on the display.
You can place a diamond-shaped marker on the signal peak to find
the signal's frequency and amplitude.
To activate a marker, press the
section of the front panel). The
inverse video to show that the marker is the active function. Turn
the knob to place the marker at the signal peak.
You can also use the
marker at the highest point on the trace.
Readouts of marker amplitude and frequency appear in the active
function block and in the upper right corner of the display. Look at
the marker readout to determine the amplitude of the signal.
key (located in the
Marker
Marker Normal
key, which automatically places a
Peak Search
Getting Started
Making a Measurement
MARKER
label appears in
41