Specifications

36 Chapter 5
Tracking Drifting Signals
Measuring a Source’s Frequency Drift
Tracking Drifting Signals
Measuring a Source’s Frequency Drift
The analyzer can measure the short- and long-term stability of a
source. The maximum amplitude level and the frequency drift of an
input signal trace can be displayed and held by using the
maximum-hold function. You can also use the maximum hold function if
you want to determine how much of the frequency spectrum a signal
occupies.
This procedure using signal tracking to keep the drifting signal in the
center of the display. The drifting is captured by the analyzer using
maximum hold.
Step 1. Connect the signal generator to the analyzer input.
Step 2. Set the signal generator frequency to 300 MHz with an amplitude of
−20 dBm.
Step 3. Set the analyzer center frequency, span and reference level.
Press
Preset, Factory Preset (if present).
Press
FREQUENCY Channel, Center Freq, 300, MHz.
Press
SPAN X Scale, Span, 10, MHz.
Press
AMPLITUDE Y Scale, Ref Level, 10, −dBm.
Step 4. Place a marker on the peak of the signal and turn signal tracking on:
Press
Peak Search.
Press
FREQUENCY Channel, Signal Track (On).
Reduce the span to 500 kHz:
Press
SPAN, Span Zoom, 500, kHz.
Notice that the signal is held in the center of the display.
Step 5. Turn off the signal track function:
Press
FREQUENCY Channel, Signal Track (Off).
Step 6. Measure the excursion of the signal with maximum hold:
(ESA) Press
View/Trace, Max Hold.
(PSA) Press
Trace/View, Max Hold.
As the signal varies, maximum hold maintains the maximum responses
of the input signal.
NOTE Annotation on the left side of the screen indicates the trace mode. For
example, M1 S2 S3 indicates trace 1 is in maximum-hold mode, trace 2
and trace 3 are in store-blank mode.