ECG Feature Extractor - How to extract features of all Channels

[dinamedy]

Hi,

I'm a new user of biomedical Toolkit 201 and currently using it for ECG Feature Extraction, I use ECG files from the ptbdb physionet database  http://www.physionet.org/physiobank/database/ptbdb/ .

Each ECG file contains 14 input channels.

When I load a file of the database (.hea) in the File settings of the ECG Feature Extractor, I see the 14 channels in the File contents and they are all selected. But when I launch the extraction, only one channel is extracted, it's the one who is selected by default in properties of file settings. I can change the channel in properties and extract its features but I don't know how to extract the features of all the channels of the file at the same time . is it possible ? if yes, How ?

I need to do this cause I need to extract features of a lot of files in this database, and doing it manually is quite complicated.

if it's not possible in Biomedical Toolkit, is it possible by writing a program in Labview ?

Thank you,

Regards.

[Xuesong_Liu]

Hi,

The ECG Feature Extractor application now only supports one channel.

You can write a VI in LabVIEW to do this automatically. Biomedical Toolkit provides a set of VIs for you to write your own biomedical applications in LabVIEW. You can use Read Biosignal Express VI to read multiple channels at the same time and then use ECG Feature Extractor VI to process these channels one by one.

You can find an example about how to use these VIs by searching "ECG Feature Extractor" in NI Example Finder.

[dinamedy]

Hi,

Thank you for your answer, I'll try your suggestion.

[dinamedy]

Hi......

I started to write my own vi for Multichannels ECG extraction using Read biosignal vi, normally Read Biosignal support the MIT database format. I have a question about using this format :

==> Can I just indicate the .hea file and the file path parameter and put the .data and .atr in the same directory ?

==> Or I have to indicate the "channel names in" and "the group name in" parameters ?

If you have any example of using Read Biosignal with .hea it'll be perfect.

Thanks

[Xuesong_Liu]

Hi,

Yes, you just need to put the .hea, .dat and .atr file in the same folder. Read Biosignal Express VI only need the path of .hea file.

"channel names" and "group name" are optional. For .hea file, if you do not specify these two parameters, all channels will be read.

[dinamedy]

Thank you for your answer, but I still have some questions :

If I don't specify the channel, in which order the channels are read (for example for a MIT database file of 2 channels http://www.physionet.org/physiobank/database/mitdb/100.hea) :

1/Does it read the first channel until the end of file and then the second channel after ? or each time it reads 2 values, one for the first channel and the second one for the second channel?

2/In the two cases how can we make the difference if we use the ECG feature Extractor. vi between the features of the first channel and the features of the second ?

3/what is the unit of time of onset and offset of ECG features (P, T, QRS) ? 

4/ I use the "format into file" function to write the output of "ECG feature Extractor.vi" into a file as a text, is this function appropriate ?

Thank you

[Xuesong_Liu]

Hi,

If you don't specify any channel, the order of the channels read will be the same with that defined in the .hea file.

1. In Read Biosignal Express VI, all channels will be read simultaneously. You can use Convert from Dynamic Data VI to convert the output to 1D array of waveform, with each element corresponding to one channel.

2. ECG Feature Extractor VI can only accept one channel of data. So you should drop multiple ECG Feature Extractor VIs, according to you channel number.

3. The unit is second.

4. It depends on your requirement. If you want to write all features as text to a file, I think this function will work.

[shams71]

hi i research on electrocardiam cardiogram data acquisition and analysis using LabVIEW....still i lagging on the how to get a signal through the hardware in realtime and also i try to get a signal through the file path...please sugges me how to start and post a link of documents