3-4 Setting Amplitude Parameters Spectrum Analyzer Measurements
3-8 PN: 10580-00447 Rev. H Spectrum Analyzer MG
3-4 Setting Amplitude Parameters
The amplitude scale corresponds to the y-axis display. The instrument supports both log units (such as dBm
and dBV) and linear units of scale (such as volts or watts). Amplitude-related parameters are set using the
“AMPLITUDE Menu” on page 3-12.
Setting Amplitude Units
This setting allows you to set the y-axis graticule units and applies to most of the spectrum analyzer
measurements, including markers, traces, and limit lines. To change the amplitude units:
1. Select AMPLITUDE > Y AXIS UNIT.
2. Select the desired y-axis amplitude units from the following:
• Logarithmic:
• Spectrum analyzer measurements: dBm (default), dBV, dBmV, dBµV, or dBA
• Field strength and EMF measurements (Option 444): dBm/m
2
, dBW/m
2
, dBV/m, dBmV/m,
dBµV/m
• Linear:
• Spectrum analyzer measurements: Volt (scalable to V, mV, µV, nV), Watt (scalable to W, mW, µW,
nW, pW, fW), and A (scalable to A, mA, µA, nA)
• Field strength and EMF measurements (Option 444): V/m, W/m
2
, W/cm
2
, A/m
When switching amplitude units, the following parameters are affected as described below:
• Reference level is converted directly from the current unit into the new unit and scaled appropriately.
For example, if the current units are dBm and ref level is set to –30 dBm, when changing the units to
volts, the ref level is converted to 0.00707 V and scaled to 7.07 mV.
• The reference level offset is always entered in dB. When linear units are selected, the dB offset is
converted to an offset to match the selected units and applied to the measurement displays.
• When changing from log units to log units, scaling (dB/div) remains unchanged. When changing from log
units to linear units, scaling is not applicable in linear units.
• When a linear unit is selected, the top graticule line is set to the value of the converted reference level
and the bottom line of the graticule is set to zero. The remaining graticule lines are calculated by
dividing the reference level into 10 equal parts. For example, if the ref level is 5 mv, the graticule lines
will be labeled as follows (from top to bottom): 5.00, 4.50, 4.00, 3.50, 3.00, 2.50, 2.00, 1.50, 1.00, 0.00.
• Trace in a “HOLD / VIEW” mode will be scaled to match the newly selected units.
• Marker amplitudes will be scaled to match the newly selected units.
• Limit line points will be directly converted and displayed in the newly selected amplitude units.
• Trigger levels will be converted to the newly selected units.
• Measurements and setups will be converted to the newly selected units.
• Save and recall will retain the units configuration.
• Power cycle will retain the current units configuration.
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