ROSE-HULMAN INSTITUTE OF TECHNOLOGY
Department of Electrical and Computer Engineering
ECE 310 Communication Systems Spring 2006
BAF
Hints on Spectrum Analyzer Measurements
Agilent E4402A Spectrum Analyzer
1. The Spectrum Analyzer (SA) is an important tool for analyzing the frequency content of
signals, and is a basic instrument of importance in a number of fields in electrical and
computer engineering. This document is a quick start on using the Agilent SAs available in
Room D115. Additional information on reading SA displays is available in the PowerPoint
document “Reading SA Displays”.
2. It is usually a good idea to check the calibration of the SA before you begin using it, even if
the unit is “self-calibrating”, as is the E4402A. We will also use this operation to learn how
make a basic measurement. A reference signal is available at a connector on the lower front
of the unit, to the right of the input connector. Connect this signal to the spectrum analyzer
input using a BNC-BNC coaxial cable. Activate the reference signal by pressing the
INPUT/OUTPUT button, and then pressing the AMPTD REF OUT button. The calibration signal
provides a reference signal at 50 MHz and a level of -20 dBm.
3. Now, set the display to show the reference signal spectral content. First set the center
frequency of the display to 50 MHz by pressing the FREQUENCY button and entering this
value. Next, set the range of frequencies shown across the display to 10 MHz by pressing
the SPAN button and entering this value. You should see the spectrum corresponding to a
sinusoid of frequency 50 MHz. The peak of this line should appear in the exact center of the
screen.
4. The next setting to adjust is the reference level, which sets the signal power level
corresponding to the top line of the display. There are two settings to be adjusted here. First,
set the units for the display. Suppose we wish to use dBmV. Press the AMPLITUDE button,
then press MORE, then Y AXIS UNITS. Select DBMV. Next, set the reference level to a
convenient value. For example, 60 dBmV corresponds to 1 Vrms. Press the AMPLITUDE
button, then press REF LEVEL, and enter “60 dBmV”. Now the top line of the display
corresponds to a signal level of 60 dBmV. Your display should look like that shown in
Figure 1 below.
Page 1 of 3
