3-9 Setting Up Markers Spectrum Analyzer Measurements
3-48 PN: 10580-00447 Rev. H Spectrum Analyzer MG
Marker Functions
Noise Markers
Noise Markers use an averaging routine applied to multiple data-point groups to calculate the readout, which
is typically comparable to using 1 Hz bandwidth filtering. Because the noise marker routine uses groups of
data points for the calculation, the noise marker should not be placed in close proximity to measurable signals.
You can observe this effect by moving the marker further away from a signal until the marker readout
stabilizes to a more consistent value. Noise markers should be used with an RMS/Avg detector type for proper
measurement. When a noise marker function is selected, the marker amplitude value is displayed in
amplitude units/Hz, which is the noise level within the resolution bandwidth filter. Delta markers can also be
put into a noise function, but the reference marker must also be a noise marker. If they are different functions,
one will be updated to match the other. Fixed markers are not allowed to be set to a noise function, so if a noise
marker is changed to fixed mode, the function will automatically be set to off.
Frequency Counter Marker
Sets the frequency counter for the selected marker. Marker frequency values are normally limited in resolution
to individual display pixels. Each pixel may represent multiple frequencies. When counter marker is enabled, a
higher resolution digital signal processing is used within the region of the counter marker to determine a more
precise frequency. Using counter marker in association with marker to peak will result in the frequency of the
signal peak to a much higher displayed resolution. Note that frequency accuracy is affected by the RBW
setting, and sweep times may be longer when using counter marker because of the additional signal
processing. Frequency Counter markers are not available in zero span.
Quasi-Peak Marker
Quasi-Peak markers are designed to provide a weighted average amplitude for pulsed or high AM content
signals. Typically, the result from a Quasi-Peak measurement will be lower than the same signal measured
with a peak detector. When a marker function is set to Quasi-Peak, the resolution bandwidth and video
bandwidth are automatically set and the amplitude is evaluated at the marker frequency according to the
CISPR 16-1-1 specification.
Quasi-Peak markers can only be applied to signals below 1 GHz. Quasi-Peak markers are not available in zero
span. Typically, when using Quasi-Peak markers, the amplitude axis is set to dBµV. This is set via:
AMPLITUDE > Y AXIS UNIT > dBµV.
One or more markers can be enabled to apply the Quasi-Peak function. If the Quasi-Peak marker is set on a
signal, at the end of each sweep the analyzer tunes to the position of each marker and remeasures the marker
amplitude applying the CISPR time constants and filters. The CISPR filter of 200 Hz, 9 kHz, or 120 kHz is
applied automatically depending on the marker frequency as follows:
• Band A: 9 kHz to < 150 kHz, 200 Hz filter
• Band B: 150 kHz to < 30 MHz, 9 kHz filter
• Band C&D: 30 MHz to 1 GHz, 120 kHz filter
Note
The functionality of frequency counter and quasi-peak marker functions is disabled in AM/FM Audio
measurement, so only the user set marker frequency value will be displayed.
To Next Page
Loading...
