Explanation of logarithmic representation

Normally, the y-axis has a linear scale on the oscilloscope. One grid division always has the same value according to the selected setting (Unit/Div). However, as well as the linear representation, the y-axis can also be changed to a logarithmic scale. The advantage of the logarithmic representation is that signals of various orders of magnitude can be better displayed and so smaller signals in particular more easily recorded.

Formula 

In order to be able to convert the power (reference variable 1 mW) into currents there must always be a reference to a defined terminal resistance.

P = 10 x log (P E/1 mW) dB

For the variables of current and voltage, the following formula can be derived:

A_U = 20 x log (I_A /I_E ) dB

Example 

In the logarithmic view, the indication range always goes from 0 A to the maximum current clamp reading (full scale). The y-axis can be explained with the aid of the screenshot and the table below. There are no changes to the time range (x-axis) compared with the linear view.

Fig 1: Display - Logarithmic Representation, Explanation Of Y-Axis

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