How to filter data in spread sheet file?

[SvenSchroeder]

Hi,

I am only using a setup with Labview 6i and the DAQ vi sample "Display Acq'd SpreadSheet file.vi" from the Streamdisk-Library to read old files recorded some time ago (well, several years) with the corresponding "Cont Acquisition to Spreadsheet file.vi" (recorded at 100 Hz or 250 Hz). The files are quite large, over 100 MB, as the recordings lasted several hours, sometimes a few days.

Most of the files are fine, no noise, just a plain baseline, and once in a while they show some peaks of different height and length.

But some files show a bad noise, which superimposes on the signal. As I just have to count "events per minute", I am quite handicapped with this noise, b/c (1) the recordings cannot be done again, (2) I have never learned to work with Labview programming, I just know how to read a file and move around in the vi mentioned above (to count the events manually).

I attached two files: one shows the noise in higher magnification, the second the signal with a few peaks, probably 4 or 6, but I cannot be sure how many there really are - BUT that is the only question I am interested in.

I tried to find another example vi (here in the forum), which allows me to filter the data in a spreadsheet file, but I was not succesful. And, as I already wrote, I have not a clue how to modify the vi I use, that is, how to include filtering in it. And I don't have time to learn how to program Labview, that might take longer then the time I have left for my thesis...

So, if somebody has a working solution, PLEASE post it or email it to me!

Thank you a lot!

Sven

[ramses64]

Sorry,
I don't see any attached file...

[SvenSchroeder]

Ups - the upload of the pictures did not work? I try it again...

[ramses64]

Hey,
If I well understood your problem, you want to denoise a signal ?
I can't save a vi for a 6 version of labview, only 8.x...

What I can suggest to you is to use a spline cubic, that I ever explained in this thread :
http://forums.ni.com/ni/board/message?board.id=170&message.id=328687#M328687

Let me know if it can help you.
Best regards,

Message Edité par ramses64 le 06-12-2008 08:53 AM

[SvenSchroeder]

Yes, I want to denoise the recording! The solution you posted in the other thread looks as if it might work for me. I think we have a few computers with Labview 8 in one of the student labs, they have been replaced some time ago, I will check this out. Is there still the Streamdisk-Library included in v 8.5? Then I can just go to do the work there when no course is running! Thanks a lot for your reply! Sven

[ramses64]

Hey,
yes I think the library is included by default in Labview 8.5
best regards,
Vincent

[SvenSchroeder]

OK, I get access to a PC with Labview 8 with Applicationbuilder - this PC is/was used to build applications for a student lab course in neuroscience. The course PCs just have the runtime installed. The person who was responsible for this retired last year, so I cannot get help here at the department. But how do I connect the filter with the "Display Acq'd Spreadsheet File.vi"? And then I will have to find out how to convert the vi to a stand alone runtime with the PC mentioned above. Well, looks like a long weekend... Sven

[ramses64]

If I well understood your problem, you have saved datas, and now you would like to filter them.
You just have to read your datas, and link to the spline cubic method.
If you have a little file that I can read, I can make you an exemple.
Best regards,
Vincent

[SvenSchroeder]

Yes, I would like to increase the signal-to-noise ratio in files like the one in the zip-file attached to this posting: this is a recording, sampling frequency 250 Hz, and it is a plain txt-file with the following structure

250,000
#,###
#,###
#,###
(...)

Message Edited by SvenSchroeder on 06-13-2008 02:35 AM

Message Edited by SvenSchroeder on 06-13-2008 02:36 AM

[ramses64]

Re,
see attached files :
1) the signal non filtered
2) the signal filtered with a parameter 0.9999999
3) the signal filtered with a parameter 0.9999

I didn't understood what you wanted to remove from your signal : is it the peaks, or the noise ?
let me know if it's good for you, and I will send you the VI in 8.5 (or in 8.0 if you want)

Best regards,
Vincent