Log Mag and Linear Mag (Trace Format)

Menu Path: Trace > Format > Format:

Selecting the Log Mag or Linear Mag trace format selects logarithmic- or linear-magnitude data for the active trace.

Select Linear Mag to show the trace on a linear Y-axis scale. This means that the y-axis value for a point is sqrt( I^2 + Q^2 ).

Select Log Mag to show the trace on a logarithmic (decibel) Y-axis scale.

Select Log Mag (lin) to show the trace on a logarithmic Y-axis scale. The difference between Log Mag (lin) and Log Mag is that the Y-axis annotations are shown in linear units (Vrms, for example) when Log Mag (lin) is selected instead of logarithmic units (dBm deciBels referenced to a milliWatt: dB relative to 1 milliwatt dissipated in the nominal input impedance of the analyzer, for example).

Characteristics

Here are some characteristics you should know:

• For Log Mag, all points on the y-axis have a logarithmic relationship (regardless of the vertical unit selected).
• For Linear Mag, all points on the y-axis have a linear relationship (regardless of the vertical unit selected).
• For frequency-domain measurements, frequency is shown on the x-axis.
• For time-domain measurements (time records), time is shown on the x-axis.
• For Log Mag or Linear Mag, the magnitude readout in the Markers Window for a delta marker shows the magnitude ratio between the delta marker and the reference marker.