Technical data

82 Chapter 5
Spectrum Analyzer
Measuring Multiple Signals
Spectrum Analyzer
Resolving Signals of Equal Amplitude
In this procedure a decrease in resolution bandwidth is used to resolve
two signals of equal amplitude with a frequency separation of 100 kHz.
Notice that the final RBW selection to resolve the signals is the same
width as the signal separation.
Step 1. Connect the output of signal generator #1 to port 2 of the directional
coupler and connect the output of signal generator #2 to port 3 (the
coupled port) of the directional coupler as shown in Figure 5-7.
Figure 5-7 Setup for Obtaining Two Signals
Step 2. Set the signal sources as follows:
Set signal generator #1 to 300 MHz at –19 dBm. Set signal generator #2
to 300.1 MHz at –4 dBm (this higher power level overcomes the
nominal 16 dB loss through the coupled arm of the directional coupler).
The amplitude of both signals should be approximately −20 dBm at the
output of the bridge.
Step 3. Setup the analyzer to view the signals:
Press
Mode Preset.
Press
FREQ Channel, Center Frequency, 300, MHz.
Press
SPAN X Scale, Span, 2, MHz.
Press
Meas Setup, Avg Mode, Exponential, Avg Number, 25, Enter.
Press
Trace/Detector, Average.
Press
BW, Res BW (Manual), 300, kHz.
A single signal peak is visible. See Figure 5-8 for an example.