ADInstruments AD8000 Series Instruction Manual page 86

AD8000 Series Spectrum Analyzer Instruction
Manual
b) Rotate the knob. The step change is 1/500 of the span.
c) Manually input the frequency. When the span is zero, it could not be
entered manually. Only 2 methods before are usable.
(2) Delta Mark
After pressing this soft-key, two markers will appear on the screen. The
start positions of these two markers are the same, so the amplitude
difference and frequency/time difference here are 0. Rotating the knob,
pressing the 'Up/Down' cursor or manually inputting the frequency value
can change the position of the second marker. The amplitude and
frequency/time difference between two markers will be displayed on the
up-right of the screen. The main function of 'Delta Mark' is to compare two
signals.
(3) Fixed Mark
'Fixed Mark' is similar to 'Delta Mark': the main function is also to view the
difference of two markers and the method to change the position of the
second signal is the same. Differently, the first marker of delta mark
indicates the signal frequency and amplitude of that point, but the first
point of fixed marker indicates the amplitude of that frequency point which
has nothing to do with the signal. The marker would remains at the orignal
amplitude if the signal amplitude increases. Its position will not change with
the signal again only if the reference level or the frequency is changed (the
frequency and amplitude of the frequency point remain unchanged).
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Fig. 3-48 Delta Mark