Jackson Labs PHASE STATION 53100A, User Manual, Page: 66 / 225

PhaseStation 53100A User’s Manual V1.04 25-Apr-2022 66
The spur table
The
spur table
is a list of all coherent amplitude- or phase-modulated spectral
components detected by the instrument in the course of measuring AM noise or phase
noise, respectively. Each plot acquired from an instrument that supports spur detection
has its own spur table. Spur levels are reported as CW power levels relative to the
carrier, each at a given offset from the carrier frequency.
Figure 28: Typical phase noise measurement with accompanying spur table
The default Spur Threshold value of 6 dB, specified in the Additional options page of the
53100A acquisition dialog, ensures that artifacts of lower amplitude relative to neighboring
areas of the trace are not classified as spurs. To illustrate the difference between coherent spur
amplitudes and their apparent levels on the 1-Hz normalized noise trace in the figure above,
Trace→Suppress spurs in noise traces (Ctrl -s) is disabled, and Trace→Mark spurs in noise traces
(Ctrl-m) is turned on.
Show or hide known spurs
Several commands in TimeLab determine how spurs are handled in phase noise and AM
noise graphs:
•
Trace → Mark spurs in noise traces ( Ctrl-m ) draws shaded or dashed lines,
depending on the Trace → Toggle trace thickness for current measurement ( T )
setting, for each detected spur on the AM or phase noise graphs. These lines reflect
the amplitude of each spur as reported in the spur table,
which will not be the same
as the level of any corresponding bumps or spikes in the noise trace itself. Because
phase noise and AM noise traces undergo normalization to 1 Hz bandwidth, the Y-