Keysight N9915-90020 User’s Guide 261
RTSA (Real-time Spectrum Analyzer) Mode—Option 350
RTSA Mode Settings
Scale and Units
Adjust the Y-axis scale to see the relevant portions of the data trace.
The Y-axis is divided into 10 graticules. A acquisition is shown on the screen as
a solid horizontal bar that can be placed at any graticule.
RTSA always uses logarithmic scale. The Y-axis reference line represents the
specified absolute acquisition (dBm). Y-axis graticules show dB below or above
the reference line.
When RF Attenuation set to Auto, the RF Attenuation is coupled to acquisition.
How to set Scale
Press Scale / Amptd
. Then choose from the following:
Manually set Scale, acquisition, and Reference Position.
—
Scale Manually adjust the dB scale per division to view specific areas of the
current trace. Enter a value using the numeric keypad, the arrows, or
the rotary knob. Then press Enter
.
— Ref Level Manually set the value of the reference line. Enter a negative
value by pressing Run/Hold (+/-) either before or after typing a value. This
can also change the RF Attenuation setting. See
“Attenuation Control” on
page 262
.
—
Ref Pos Manually set the position of the reference line. Values must be
between 0 (top line) and 10 (bottom line). Default position is zero (top).
External Gain
When using an external amplifier or attenuator, the RTSA mode trace
amplitude values can be offset to compensate for the effect of the external
device. This effectively moves the reference plane of the RTSA measurement
port out to just beyond the external device. For example, when using an
external preamp with gain of +10 dB, enter this value for External Gain, and the
data trace across the displayed frequency span will be adjusted down by
10 dB.
When RF Atten is set to Auto, you may see a change in the RF Attenuation
value. This is an attempt to measure the signal at top of screen (the
acquisition) without overloading the RTSA first mixer.
How to Set External Gain
—Press Scale/Amptd
.
—Then
External Gain
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