Hello,
I am having some confusion with the function of "plot harmonic at harmonic frequency, in REW 5.30. I have scaled the distortion plot for dBr, and expect that checking the "plot harmonics at the harmonic frequency" simply shifts the harmonic display accordingly, for example 3rd harmonic will be shifted in freq 3x, with no change to the harmonic levels. This is not occurring. I believe there may be an error in the way "use harmonic freq as ref" is being used, which is automatically checked and greyed out when "plot harmonics at the harmonic frequency" is checked.
Here is an example, a nice tweeter is tested, the cursor placed at ~4kHz showing 3rd harmonic level of 0.167%.
Check "plot harmonics at harmonic frequency", and 3rd harmonic level at ~12kHz is now shown as 4%, quite an increase.
As far as I can tell, the 3rd harmonic is being shifted by 3x, and then the "use harmonic freq as ref" is shifting the reference 3x again to 36kHz which is very incorrect. The same view shows as "SPL" does not show this error, the 3rd harmonic is simply shifted 3x to the right as expected. You can see here, that the amplitude at 36kHz is at 77.5dB, harmonic level at 12kHz is 49.5dB, so -28dB = 4%, but this is quite wrong math for 3rd harmonic generated at 4kHz.
I am having some confusion with the function of "plot harmonic at harmonic frequency, in REW 5.30. I have scaled the distortion plot for dBr, and expect that checking the "plot harmonics at the harmonic frequency" simply shifts the harmonic display accordingly, for example 3rd harmonic will be shifted in freq 3x, with no change to the harmonic levels. This is not occurring. I believe there may be an error in the way "use harmonic freq as ref" is being used, which is automatically checked and greyed out when "plot harmonics at the harmonic frequency" is checked.
Here is an example, a nice tweeter is tested, the cursor placed at ~4kHz showing 3rd harmonic level of 0.167%.
Check "plot harmonics at harmonic frequency", and 3rd harmonic level at ~12kHz is now shown as 4%, quite an increase.
As far as I can tell, the 3rd harmonic is being shifted by 3x, and then the "use harmonic freq as ref" is shifting the reference 3x again to 36kHz which is very incorrect. The same view shows as "SPL" does not show this error, the 3rd harmonic is simply shifted 3x to the right as expected. You can see here, that the amplitude at 36kHz is at 77.5dB, harmonic level at 12kHz is 49.5dB, so -28dB = 4%, but this is quite wrong math for 3rd harmonic generated at 4kHz.
