Technical data

Chapter 5 93
Spectrum Analyzer
Measuring a Low−Level Signal
Spectrum Analyzer
Trace Averaging
Averaging is a digital process in which each trace point is averaged with
the previous average for the same trace point. Trace averaging can
facilitate identifying and characterizing a CW or narrowband signal,
such as a carrier or tone in the presence of noise or other broadband
signals.
Selecting averaging, when the analyzer is auto coupled, changes the
detection mode from peak to average, smoothing the displayed noise
level.
Step 1. Connect the RF Output of the signal generator to the analyzer RF Input
as shown in Figure 5-7.
Figure 5-18 Setup for Obtaining One Signal
Step 2. Set the frequency of the signal source to 295 MHz. Set the source
amplitude to −80 dBm. Connect the source RF OUTPUT to the analyzer
RF INPUT.
Step 3. Select the spectrum analyzer mode:
Press
Mode, Spectrum Analyzer.
Step 4. Preset the analyzer:
Press
Mode Preset.
Step 5. Set the center frequency, span and reference level:
Press
FREQ Channel, Center Frequency, 295, MHz.
Press
SPAN X Scale, Span, 5, MHz.
Press
AMPTD Y Scale, Ref Level, 40, −dBm.
Step 6. Turn trace averaging on:
Press
Meas Setup, Avg Number, 100, Enter.
Press
Trace/Detector, Average.
As the averaging routine smooths the trace, low level signals become