q
Scale — Activates the scale function which sets the dB/division value from 1
dB/div to 15 dB/div in 1 dB steps. This soft key is not active if the units are
set to linear.
q
Atten/Preamp — Sets the internal input attenuator so that it is either coupled
automatically to the reference level (
Auto), manually adjustable (Manual)or
dynamically coupled to the input signal (
Dynamic) and provides control for
the preamplifier.
q
Auto — Sets the input attenuator so that it is coupled automatically to the
reference level.
q
Manual — Sets the input attenuator manually from 0 to 51 dB. Choose a
value that does not overload the instrument.
q
Dynamic — Sets the value of the input attenuator so that it is dynamically
coupled to the input signal and turns the preamp on or off based on the
overall signal conditions across the entire frequency range of the instru
-
ment. The instrument will set the lowest input attenuation consistent with
the need to not saturate the front end.
NOTE: A large signal that is not displayed on-screen can sometimes cause the
instrument to turn off the preamplifier or add input attenuation, causing the
noise floor to jump up or down suddenly as the large signal turns on or off.
q
Preamp Control Manual — Activates the preamp menu for manual control
of the preamplifier.
q Preamp On/Off — Sets the preamplifier on or off.
q
Preamp Auto — Automatically adjusts the preamplifier according to
the reference level.
q
Back — Returns to the previous menu level.
q
Units — Choose from the menu of amplitude related units. When Linear is
selected, the available selections are Volts or Watts. When Log is selected,
the selection of dBm sets absolute decibels relative to 1 mW as the amplitude
unit. Selection of dBV, dBmV or dBmV sets absolute decibels relative to 1
volt, 1 millivolt, or 1 microvolt respectively as the amplitude unit.
q
Ref Level Offset — Sets the reference level offset, which is a value, in dB, of
gain or loss external to the instrument. Negative values represent external at
-
tenuation. This feature allows measurement of high gain devices in combina
-
tion with an attenuator, and is used to offset the reference level to view the
correct output level. For example, to measure a high gain amplifier with an
output of 70 dBm, an external 50 dB attenuator must be inserted between the
instrument and the device. To compensate, set the reference level offset to
–50 dB.
MEAS/DISP
Pressing MEAS/DISP activates a menu of bandwidth and sweep-related func
-
tions. Use the corresponding soft key to select the desired function.
q
Spectrum — Spectrum selects a traditional spectrum analyzer display.
q
Spectrogram — Selecting Spectrogram provides a three dimensional repre
-
sentation of frequency, time and power to aid in the identification of intermit
-
tent signals. The bottom portion of the display shows a traditional spectrum
analyzer plot while the upper portion shows the power level in color with the
most recent trace placed at the bottom of the display. A color scale on the left
Chapter 2 Functions and Operations
2-47
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