REW: Software Features

[shahin17]

Hello

I've been using REW for a while now and noticed a few things I wanted to make sure I got right:
1. When we are analyzing a frequency response, what we see in the “SPL & Phase” tab is the same as the “Fundamental” amplitude and phase in the “Distortion” tab.
2. The software does not provide any information about the distortion phase (second harmonic phase, third harmonic phase, etc.).
3. Equalization is achieved by inverting the first harmonic frequency response (Fundamental) and multiplying it by input. Thus EQ also is called preEQ.
4. In REW, we don't have anything with the concept of second harmonic equalization.
Thanks

 

[John Mulcahy]

The fundamental may differ from the response shown on the SPL & Phase graph, from the Distortion graph help:

If the Analysis Preference Apply cal files to distortion is selected the results will include corrections for the cal file responses (as is the case for the RTA distortion figures). Applying the cal files provides more accurate results in regions where the fundamental or harmonics are affected by interface roll-offs but boosts the noise floor in those regions. This should be borne in mind when viewing the results. If large cal file corrections are required make sure the Analysis Preference Limit cal data boost to 20 dB is not selected. Note that any subsequent changes to the cl files will NOT update the distortion results, they are generated from the cal files that were in use at the time the measurement was made.

The fundamental and harmonic plots derived from sweep measurements are smoothed to 1/24 octave. This cannot be adjusted.

Harmonic phase is available on the RTA when measuring tones.

Equalization is achieved by inverting the first harmonic frequency response (Fundamental) and multiplying it by input.

No.

In REW, we don't have anything with the concept of second harmonic equalization.

You cannot alter non-linear behaviour through a linear process.