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april.d.johnston
USA
3 Posts |
 Posted - 04/20/2015 : 1:12:14 PM
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Origin Ver. and Service Release (Select Help-->About Origin): OriginPro 2015 (32 bit)
Operating System: Windows 7
Hello,
I have essentially the same question as this post from 2012, but the links no longer work:
http://www.originlab.com/forum/topic.asp?TOPIC_ID=18170
I would like to convert the scale to frequency (pseudofrequency) from a Morlet continuous wavelet transform. Is there now a function to do this in Origin, or will I need to compute it separately? If so, I think I need more information on how/if the 'wave number' from the cwt dialog box relates to the central frequency, as that is needed to calculate frequency.
My sampling frequency is 10kHz, so sampling interval is 0.0001 sec, and scales are 0-1000.
Thanks! |
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JacquelineHe
287 Posts |
Posted - 04/21/2015 : 04:06:21 AM
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Hi,
The online documentation is updated, so the old links are broken.
For the Continuous Wavelet Transform tool, pleaes refer to this help page and take a look at the dialog setting and algorithm.
http://www.originlab.com/doc/Origin-Help/Continuous-WaveTrans
Thanks
Jacqueline
OriginLab
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april.d.johnston
USA
3 Posts |
Posted - 04/22/2015 : 12:56:23 PM
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Hi Jacqueline,
The documentation helps a little bit to better understand the math behind the wavelet, but I still am not sure how to properly convert the scale to pseudofrequency. If I check the 'use pseudofrequency' button, there is nowhere to input my sampling frequency, so I think Origin is using a default sampling frequency, is there any way to override this?
Thanks,
April |
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JacquelineHe
287 Posts |
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april.d.johnston
USA
3 Posts |
Posted - 04/23/2015 : 3:05:04 PM
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Hello,
Yes, I understand that the algorithm for computing the wavelet isn't based on the sampling frequency, because it is based on scale, but to convert the scale in to pseudo-frequency, which is found just below the wavelet algorithm on the attached link, the equation uses delta, which is the sampling period, which IS based on the sampling frequency.
My question is not about the wavelet algorithm itself, but rather the built in pseudo frequency conversion. How can the sampling period be taken into account if I've never told Origin what my sampling period is?
Thanks,
April |
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Morlet wavelet scales to pseudofrequency