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Harmonic Distortion Question & Request
PostPosted: Sat Nov 11, 2006 10:01 pm Reply with quote
Charlie
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Joined: 28 Apr 2005
Posts: 51
Location: Charlotte, NC USA




I have been doing a lot of measurements lately to quantify the distortion of a small high frequency driver. As a result of this I have a request for a new feature and a question as to why something doesn't seem to work as expected.

After taking a log sweep measurement and selecting the Harmonic Distortion display H1 - H7 are displayed. This can make it difficult to discriminate aspects of different curves. Would it be possible to add a section to the Options for Distortion that would allow for the selection which harmonics are displayed? This way if one is primarily interested in H2 & H5, they can be shown while suppressing the others. This could be applied to K2 – K7 as well.

Since I have been measuring a 1" dome tweeter I have not wanted to excite it with low frequency content. To that end I created a custom signal; log sweep from 800 Hz - 24 kHz. After making a measurement with this signal I selected the Harmonic Distortion display. I received an error message that the “stimulus was not a pink sweep”. Why does this error message appear when the signal was indeed pink?

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Charlie Hughes
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PostPosted: Mon Nov 27, 2006 11:51 pm Reply with quote
Jim Mobley
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Joined: 27 Jul 2005
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Location: Foothill Ranch, California, USA




Hi Charlie,

I can't speak to the partial log sweep problem, but each of the harmonics shows up individually in the overlay where you can switch them on and off at will.

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Jim Mobley
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Renkus-Heinz, Inc.
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PostPosted: Wed Dec 20, 2006 2:06 pm Reply with quote
Stefan
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Joined: 19 Apr 2005
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Location: Berlin, Germany




Hello Charlie,

thank you. Both of your comments have been registered as requests for future improvements to EASERA.

Regarding the band-limited pink sweep you are right that at present EASERA only allows using broad-band pink sweeps as excitation signal for distortion analysis.

Stefan

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PostPosted: Fri Jun 12, 2009 3:19 pm Reply with quote
hadisumoro
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Joined: 01 Oct 2007
Posts: 39
Location: USA




Stefan, Jim, Bruce,

In the distortion post processing (especially Relative Spectra), is it possible (in the currect EASERA PRO version) to show the result in percentage relative to the fundamental? If not, it may be a useful feature for v1.2 and up. Thank you.

Hadi
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PostPosted: Sat Jun 13, 2009 3:46 pm Reply with quote
Charlie
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Joined: 28 Apr 2005
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Location: Charlotte, NC USA




Hi Hadi,
For the display choose Relative Spectra under Distortion. Select the harmonic of interest (e.g. K5). At the top of the y-axis, right-click on the units type. This will bring up a dialog box to select alternate units. Select % and click OK. The harmonic will then be displayed as percentage relative to the fundamental.

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Charlie Hughes
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PostPosted: Mon Jun 15, 2009 2:09 pm Reply with quote
hadisumoro
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Charlie,

Thank you for the info. I just realized if I can right-click on the x-axis too.

Hadi
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