I have a question about Data Reduction in EMC32. It's about the Subrange Maxima Search. How are the frequency ranges defined for Subrange Maxima Search?
In my case I have a Test from 30MHz to 1GHz with 10 subranges. How are the frequency ranges subdivided?
In EMI Scan Mode you open the EMI Evaluation function "Subrange Maxima" from menu via "Test" => "EMI Anlaysis".
Here you can choose between linear, logarithmic or UN R10 for interpolation.
With "Linear" the subranges are equidistant according to linear scale, with "Logarithmic" the subranges are equidistant according to logarithmic scale.
In case of UR R10, subranges are defined in fixed ranges according to standard E/ECE/324/Add.9/Rev.4/E/ECE/TRANS/505/Add.9/Rev.4 clause 4.3.
In the EMI Auto Test, the logarithmic interpolation is always used, unless the UN R10 option is selected.
In practice, logarithmic is used because Limits are usually also defined in logarithmic scale.
No matter if you choose linear or logarithmic, you will always find the highest levels. If you don't measure over several decades, the differences between linear and logarithmic are not too big. If you have any doubts, it is recommended to increase the number of subranges. In the EMI Auto Test you have also the possibility to find more critical frequencies via the Evaliation Path 1 with the "Peak Search" function and "Maxima Limitation".
