Specifications

32 Chapter 4
Improving Frequency Resolution and Accuracy
Using a Frequency Counter to Improve Frequency Resolution and Accuracy
Improving Frequency Resolution
and Accuracy
Using a Frequency Counter to Improve
Frequency Resolution and Accuracy
This procedure uses the spectrum analyzer internal frequency counter
to increase the resolution and accuracy of the frequency readout.
Step 1. Preset the analyzer:
Press
Preset, Factory Preset (if present).
Step 2. Enable the internal 50 MHz amplitude reference signal as follows:
(PSA)
Press
Input/Output, Input Port, Amptd Ref.
(ESA E4401B and E4411B)
Press
Input/Output, Amptd Ref (On).
(ESA E4402B, E4403B, E4404B, E4405B, E4407B and E4408B)
Connect a cable from the front panel AMPTD REF OUT to the analyzer
RF input:
Press
Input/Output, Amptd Ref Out (On).
Step 3. Set the center frequency to 50 MHz and the span to 80 MHz:
Press
FREQUENCY Channel, Center Freq, 50, MHz.
Press
SPAN X Scale, Span, 80, MHz.
Step 4. Turn the frequency counter on:
(ESA) Press
Freq Count.
(PSA) Press Marker Fctn, Marker Count, Marker Count (On).
NOTE The frequency and amplitude of the marker and the word Marker
appears in the active function area (this is not the counted result). The
counted result appears in the upper-right corner of the display to the
right-side of Cntr1.
Step 5. Move the marker, with the front-panel knob, half-way down the skirt of
the signal response.
Notice that the readout in the active frequency function changes while
the counted frequency result (upper-right corner of display) does not.
See Figure 4-1. To get an accurate count, you do not need to place the
marker at the exact peak of the signal response.
NOTE Marker count properly functions only on CW signals or discrete spectral
components. The marker must be
> 25 dB above the displayed noise
level.