Agilent Spectrum Analysis Basics - Agilent Technologies

Delta marker: A mode in which a fixed, reference marker has been
established and a second, active marker is available that we can place
anywhere on the displayed trace. A read out indicates the relative frequency
separation and amplitude difference between the reference marker and
the active marker.
Digital display: A technique in which digitized trace information, stored
in memory, is displayed on the screen. The displayed trace is a series of
points designed to present a continuous looking trace. While the default
number of display points varies between different models, most modern
spectrum analyzers allow the user to choose the desired resolution by
controlling the number of points displayed. The display is refreshed (rewritten
from data in memory) at a flicker-free rate; the data in memory is updated
at the sweep rate. Nearly all modern spectrum analyzers have digital flat
panel LCD displays, rather than CRT-based analog displays that were used
in earlier analyzers.
Display detector mode: The manner in which the signal information is
processed prior to being displayed on screen. See Neg peak, Pos peak,
Normal and Sample.
Digital IF: An architecture found in modern spectrum analyzers in which
the signal is digitized soon after it has been downconverted from an RF
frequency to an intermediate frequency (IF). At that point, all further signal
processing is done using digital signal processing (DSP) techniques.
Display dynamic range: The maximum dynamic range for which both the
larger and smaller signal may be viewed simultaneously on the spectrum
analyzer display. For analyzers with a maximum logarithmic display of
10 dB/div, the actual dynamic range (see Dynamic range) may be greater
than the display dynamic range.
Display scale fidelity: The uncertainty in measuring relative differences in
amplitude on a spectrum analyzer. The logarithmic and linear IF amplifiers
found in analyzers with analog IF sections never have perfect logarithmic
or linear responses, and thus introduce uncertainty. Modern analyzers with
digital IF sections have significantly better display scale fidelity.
Display range: The calibrated range of the display for the particular display
mode and scale factor. See Linear and Log display and Scale factor.
Displayed average noise level: The noise level as seen on the analyzer’s
display after setting the video bandwidth narrow enough to reduce the
peak-to-peak noise fluctuations such that the displayed noise is essentially
seen as a straight line. Usually refers to the analyzer’s own internally
generated noise as a measure of sensitivity and is typically specified in
dBm under conditions of minimum resolution bandwidth and minimum
input attenuation.
Drift: The very slow (relative to sweep time) change of signal position on
the display as a result of a change in LO frequency versus sweep voltage.
The primary sources of drift are the temperature stability and aging rate
of the frequency reference in the spectrum analyzer.
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