Technical data

Chapter 5 153
Adjacent Channel Power
Using the Adjacent Channel Power Measurement
Adjacent Channel Power
To Change Units on the Y-Axis:
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, for example, 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. To select
this feature:
• On [Range Ctrl] select
Auto to enable the E7495A/B to continuously adjust the
noise floor to the optimum setting. When you have Range Control set to Auto,
the Sensitivity Setting (see “Setting the Analyzer Input Gain” on page 154) is
automatically switched to Low whenever the signal level at the test set’s
connector (that is, after any external attenuation has been applied) rises above
–10 dBm. You can use the noise correction feature (see “Setting Noise
Correction” on page 154) to recover any lost dynamic range.
If you prefer a fixed noise floor, you can disable autoranging in two ways using the
Setup function within Spectrum Analyzer:
• On [Range Ctrl] select
Hold to fix the noise floor at the current level. A
subsequent strong signal—even outside the measurement range—may cause an
inaccurate reading due to overloading the front-end of the test set.
• On [Range Ctrl] select
Max to fix the noise floor at the current level until a
strong signal comes in. In that case, the floor will rise to maintain accuracy, but
Step Notes
1. [Level/Location]
2. [Units] Each time you press this softkey, the
selected option changes.
3. [dBm] or [Watts] There is no change made to the Y-axis.
The change is to the units for entry. The
reference level changes on the graph,
but not the axis labels.