| Author |
 Topic  |
|
|
maxclark153
Germany
Posts |
 Posted - 01/13/2008 : 4:06:07 PM
|
Hi,
I am new to originlab, so hope cna ask you expert to solve my problem.
I have a Sinus function with Gaussian Envelope and I have to find the 1/e value from the max value along the envelope ?
Do i have to use matlab ?
thansk |
|
|
Deanna
China
Posts |
Posted - 01/13/2008 : 10:35:54 PM
|
Hi, would you please explain what "the 1/e value from the max value along the envelope" is?
As for finding the envelope of a signal, you may try the smoothing tool under Analysis: Signal Processing menu if you are using Origin 8. Set Method to percentile filter and then select 100 for Percentile and a proper number (according to the frequency of sine wave) for Points of Window. Clicking ok could find the upper envelope. Similar settings but with 0 as Percentile would help to find the lower envelope.
Below is an example:
If you are using Origin 7.5, you can use this tool in our File Exchange.
Deanna
OriginLab Technical Services
Edited by - Deanna on 01/13/2008 10:37:49 PM |
 |
|
|
maxclark153
Germany
Posts |
Posted - 01/14/2008 : 05:42:31 AM
|
thanks for the reply.
First, I have to plot the envelope (Gaussin like)around the peaks
Then I have to find the point where the value drop to 1/e or 0,3679 ( from one of the peak ) and the point is in the envelope...
for example:
[URL=http://img227.imageshack.us/my.php?image=sinusgaussaw9.png] [/URL] |
|
|
|
maxclark153
Germany
Posts |
Posted - 01/14/2008 : 09:04:22 AM
|
The tool that you provide ( for originlab 7.5) how can i use it ?
After i unpacked it in origin, how can i use it ?
|
|
|
|
easwar
USA
1965 Posts |
Posted - 01/14/2008 : 12:15:46 PM
|
Hi,
Looking at your posted image, what may work better for you is the following:
1> With graph active, use the menu item "Tools->Pick Peaks" and in the dialog adjust the settings to find your positive peak locations.
2> In the main graph itself you can change the active dataset to this peak position dataset (use the Data menu and select Peaks: PkX, PkY to make that active.
3> Use the Data Selector tool in Tools toolbar to set the limits on your peak data to analyze only one part of it
4> Bring up Advanced Fitting Tool from Analysis menu, and select an appropriate function, such as expdec1, and fit your data till it converges - use bounds and fix parameters etc as desired, to control your fit
5> Once fit has converged, keep the fitting tool open and go to the Action->Results page of the fitter. There you will see FindY and FindX edit boxes. Put desired Y value into the FindY box and click FindX to find the X value for your specified Y.
Note that the Find Peaks tool creates a separate sheet with the peak x,y values and you can instead plot from that sheet and then do the fitting if desired.
The image pasted below shows result from a sample data similar to your data.
You may also want to try our latest version, Origin 8 (SR1) which has better peak finding capabilities and the fitter has more options as well. You could download the demo and try with your data.
Easwar
OriginLab
Edited by - easwar on 01/14/2008 12:17:52 PM |
|
|
|
maxclark153
Germany
Posts |
Posted - 01/14/2008 : 4:13:05 PM
|
Thanks for you guy's help ,finally solve the problem using the add on envelope function , even though a little bit complicated ...
|
|
|
| |
Topic |
|
Sinus function with Gaussian envelope - 1/e value