Technical data

418 Chapter 16
Spectrum Analyzer
Using the Spectrum Analyzer
Spectrum Analyzer
Setting the Range Control
The autoranging feature, which is built into the test set, helps ensure accurate
measurements by changing front-end amplifier gain as needed when a strong signal
threatens to overload the test set. When this occurs, the noise floor rises (as gain is
decreased), then falls again when the strong signal stops. You should leave the range
control in autorange for general use to ensure the accuracy of the measurement
results.
If you prefer to use a fixed noise floor, you can disable autoranging in two ways
using the [Setup], [Range Ctrl] function within Spectrum Analyzer:
• On [Range Ctrl] select
Hold to fix the front-end amplifier gain at the current
level. You may use [Range Up] or [Range Down] to change the noise floor. A
word of caution: when you use the
Hold setting, a subsequent strong
signal—even outside the measurement range—may cause an inaccurate reading
due to overloading the front-end of the test set. While in
Hold, you can adjust the
gain of the front-end amplifier with the
Range Up and Range Down menu keys.
The
Hold setting cannot be saved. Leaving the measurement or going into the
sleep mode will reset the Range Ctrl to
Auto.
• On [Range Ctrl] select
Max to fix the front-end amplifier gain at the current level
until a strong signal comes in. When a strong signal is received, the front-end
amplifier gain will be reduced to maintain accuracy, but it will not return to its
lower level after the strong signal stops.
If the noise floor is too high to measure the signal of interest, reducing the resolution
bandwidth will reduce the noise floor, at the expense of the measurement update
10 (Recommended) Display a marker and
set it to peak.
a. [Marker]
b. [Marker]
c. On [Type] select
Normal.
d. [Marker to Peak]
The marker value appears in the
upper right.
Pressing [Marker] on the left menu
displays the Marker menu on the
right. Pressing Marker on the right
menu selects your marker number.
Marker numbers cycle from 1 to 2 to
3 to 4, and back again, each time you
press this key.
Step Notes