EEG signal filteration

Hello Friends...I am working on my final year project to design a filter for EEG signal........and then to detect beta waves of 4Hz to 7Hz from EEG signal........i have problem while designing due to Fs=8000Hz....when fs=500Hz then filter response is right but with fs=8kHz its respons is not desired.........so help me guyzz

Thanks for your response Gerdw
I append phase and amplitude results of my FFT because I get it in tutorial to process raw signal into FFT. Is it wrong?
I want to filter the signal of 8 Hz-15 Hz and 16Hz-30Hz, then I changed from the time domain into the frequency domain, then I use a bandpass filter.
And the expected results in the form of the output signal of frequencies (8 Hz-15 Hz and 16Hz-30Hz).
I just want to see the raw signal in number so I save it into excel.
So, what I've to do to make it happen?
Thanks anyway
Sincerely,
Fajar

Similar Messages

How can I measure coherence between EEG signals using labview?

well, I have an EEG signal(a matrix 16X8498)whose lines represent the channels and collums the samples. The last line is the stimulus channel. I would like to know if I can measure the coherence between my EEG channels(lines)using labview.If,yes,is there someone who has the block diagram?

Search the Labview help for coherence and you'll find several functions (in Labview 6.1 Full Development System). The functions are in the palette Analyze >> Waveform Measurements >> Frequency Response Function (Mag-Phase) or (Real-Im).

Init/cont filter option for a multiple signals

Hi,
I have 2D array with signals from a daq device, now i want to make a highpass and a lowpass filter for all the signals, and every signal can have it's own high and lowpass filter settings and i can have any number of signals. When i connect my 2D array to a for loop and place a filter inside with the init/cont option to true, it resets itself every loop pass. When i extract one signal and pass it trough the filter it works fine. But that's not what i want, i want to have more signals filtered in different ways. I think i understand why it reset itself, in the help file of the filter it says:If init/cont is TRUE, LabVIEW initializes the internal states to the final states from the previous call to this instance of this VI. So it means that every loop pass, it has different data but the same instance... I would like to have different instances for every (for loop) pass. In the attached files the snippets and its outcome:
Any ideas?
Best regards,
Thijs
Solved!
Go to Solution.
Attachments:
highpass_multi_values.png ‏78 KB
highpass_single_value.png ‏73 KB

Hello Thijs,
I made a quick example at my side.
It's not the neatest piece of code and the initialization of the filter coefficients should be outside of the loop, but I just wanted to show the functions you could use to do this.
See attachment.
Kind Regards,
Thierry C - Applications Engineering Specialist Northern European Region - National Instruments
CLD, CTA
If someone helped you, let them know. Mark as solved and/or give a kudo.
Attachments:
Capture.PNG ‏21 KB

Synchronising recording of eeg waveforms with stimulus

Hello everybody ,
im working on a VI to average several EEG waveforms ...which is attached ..
actually each waveform entering this ' waveform averaging' VI is actually an EEG reponse to each sound click we present to the subject.
so i need each click to trigger or start the recording .. and continue recording for 17 milliseconds.
Thus if i give 1000 clicks, the averaging VI must produce the average of the 1000 waveforms.
the clicks are given as a square waveform , frequency = 10.1 Hz , TIMING mode: simulate acquisition timing , samples per second = 44000 , no : of samples = 204000 (or a figure as high)
i used the simulate signal and play waveform blocks.
for the above problem, i tried to use the trigger and gate block... i thought of connecting the simulate waveform block to the waveform averaging vi using the trigger block...but dont seem to reach anything useful ...
P.S. : this block diagram has sinusoidal signals as the example .. in reality we record EEG signals .
I wud really be grateful if u cud help me out ...
best regards
Mer
Attachments:
AverageWaveforms2.png ‏6 KB

Hi, I'm not LV expert but I think I run into some thing like yours before. What I did was checking any missing pulse or abnormal in the EEG waveform and set trigger pulse once I found it. Take a look at your signal amplitude. If your signal too low (ex: <1.25V), your counter gate won't trigger. Once you record your EEG, amplified it and use trigger VI (take a look at the LV example) to set your trigger event pulse.
BC

Impulse on periodic signal from DAQ

I'm using a myDAQ to measure a perioidic voltage signal, and I want to find the maximum and minimum of this signal. When acquiring the signal though, there seems to be a large impulse in the start of the acquisition data shown in one of the attachements. The capture is from a probe from before any filtering is applied to the signal. I'm not sure if this is an effect of the signal acquisition or something I am doing with the signal filtering, and I am new to signal processing in Labview in general.
In the picture, I acquire 2 signals at 1, split the signal at 2 (top signal is of interest), filter at 3, scale at 4, and display at 5.
Can anyone point me in the right direction of what could be going on in my code?
Attachments:
Capture2.PNG ‏34 KB
signal.PNG ‏9 KB

You might want to test the signals that you acquiring in MAX. It seems like the signal is going from 0 to -4.5 V in a short time. You are using the DAQ Assistant, which could be the source of the odd signal. I would recommend running some of the DAQmx examples. These examples can be accessed by going to Help in LabVIEW –> Find Examples -> Hardware Input and Output -> DAQmx -> Analog Input.
Using Test Panels in Measurement & Automation Explorer for Devices Supported by NI-DAQmx
http://www.ni.com/tutorial/4638/en/
Thanks,
Frank
Application Engineer
National Instruments

Would someone explain the eeg program on the NI developer zone?

I just have some basic skills regarding to the labview. i download the program to help me to build my own eeg signal collecting program. but I dont really understand how the two programs are built and how to get those two to work. Would some please explain this to me?
Thank You
http://zone.ni.com/devzone/cda/epd/p/id/6190

Hey,
Did you put the .llb files from in the _express folder as described in the directions? If so, your next steps is to open a blank VI. When viewing the block diagram, right click and navigate from the functions palette to User Libraries > Express User Libraries > Palette Menu > EEG subVi. Drag this VI onto your diagram (1, or 19 lead). If you open the context help for this object, it will tell you what each terminal is for. I recommend for now to create controls for the terminals on the right (so you can set the patient state and the # samples to read from the Front Panel).
If using the 1 lead vi, you'll want to connect the EEG data output to a Waveform Chart input.
If using the 19 lead vi, you'll want to take the data from each EEG channel and connect it to a Build Array function. Take the single output of the Build Array function and connect that to a Waveform Chart input.
If you would like to know the Sampling Rate, you can right click on the EEG vi's samping rate terminal and create an indicator.
I hope this helps you get started!
Allie
National Instruments
Applications Engineering
Attachments:
EEG VI example.png ‏26 KB

EEG analysis

Dear sir,
My project (phase1) is analysis of EEG signals using Spectral monitoring . Normally, the time domain signal is broken into short epochs of a 512 seconds and an FFT is performed on that data array. The data from the FFT is binned into frequency ranges according to standard EEG definitions: Delta, (0-4Hz), Theta (4-8Hz), alpha (8-12Hz) , etc. The cumulative power is reported. If it is above 50db then epilepsy s ther… can u guide me on this…
Actually my major problem s how to broke shoter epochs(512 samples)……
its jus a part of ma project

If the data is already saved to disk, you can read the data back epoch by epoch (512 samples, or whatever length you want) by providing an index and length parameter to read file VI. Do the FFT on each epoch, create "bins" by using array indexing VI's and sum the resulting sub-arrays, and loop for each epoch in the data file.
Please visit our Biomedical User Group for more information, resources, and discussion around these topics.
Steve
Visit the NI Biomedical User Group at:
www.ni.com/biomedusers

Eeg filter design

AOA;
Hi friends i m doing project on eeg signal acquisition in order to detect drowsy state of driver in order to prevent road accidents....for this i am using amplifier circuit and dsp kit speedy33...in order to filter eeg signal i need to design bandpass filter of 4-7Hz....but when i am design the response of filter is wrong because os sampling frequency ...that is 8000hz...i want to downsample the real time data of speedy33 kit.....how i downsample the 8000hz to 1000hz.............can anybody help me

downsampling: There is a downsampling vi , I would choose the mean option.
OR do it in old style : add 8 values up and shift 3 bit.
For the band filter: upper and lower freq of the passband AND the desiered cutoff need a specification.
What LV version plus Add on do you have?
Greetings from Germany
Henrik
LV since v3.1
“ground” is a convenient fantasy
'˙˙˙˙uıɐƃɐ lɐıp puɐ °06 ǝuoɥd ɹnoʎ uɹnʇ ǝsɐǝld 'ʎɹɐuıƃɐɯı sı pǝlɐıp ǝʌɐɥ noʎ ɹǝqɯnu ǝɥʇ'

Simulate EEG with artifacts

I want to simulate EEG and add artifacts to the signal. By using Biotoolkit I got the EEG signal without artifacts. In addition, I simulated 50Hz noise and white Gaussian noise and tried to add them to EEG. I do not want to add white noise by changing white noise amplitude in the configuration. How to add these noise?
Đặng Huy Hoàng

You can accomplish this by using a Compound Arithmetic function and doing a little bit of data type conversion. I'll include a VI snippet below. I used a Convert from Dynamic Data function and a Get Waveform Components function. Using this method you'll have to be careful what sampling rate and number of samples you set on your Generate Waveform function based on the size of data you're getting out of your Simulate EEG function. I hope this helps.
Miles G.
National Instruments
Applications Engineer

How to get the SubVI(the virtual path is under .exe) reference in Run Time System

Hi everyone
The problem is about how to get the SubVI reference in Run Time System, when the SubVI is in .exe after building.
More details:
The top vi calls the SubVI by dynamic way, so the SubVI is included always, and the source object is the application.exe.
After the setup above, the SubVI will be in the application.exe. For example, SubVI's path is ...\application.exe\SubVI.vi
So, how to get SubVI's reference in Run Time System?
I can not get it when using "open VI reference" with the path ...\application.exe\SubVI.vi in Run Time System.
Actually, I can create a file to include the SubVI, instead of build the SubVI in application.exe , then I can get the reference convenintly. But it is not my favourate way.
Thanks
chenyin
Solved!
Go to Solution.

Here is the problem. Call a dynamic subVI means users could change it but it's also very attractive.
The dynamic call must be used within a user mastered but some parade can avoid problems.
It depends of why you use dynamic calls... => 2 main ways:
- Dynamic call are use to maintain an evolutive part of the code without acting on the executable => one unique VI distribution maintained by the administrator/developer
- Dynamic call are use to provide a collection of 'external' feature which could be enriched by the administrator/developer. For example, you provide to your customer a set of custom signal filters selectable in the executable.
In the 2 cases, you are only able to assess user skills to know if there is a risk of damage if there is modification.
So, to stay alone master a parade could be to provide dynamic VI without diagram but with the problem of maintenance because no modification in situ and more attention to manage distribution.
An other way is to hide the real distribution to user => call dynamic VI but unnamed it as *.vi but other (a repulsive name as OS system name ) or simply with no extension in order to not attract user... but it's questionable...
Another method more difficult but safer is to create a test of consistency ahead of your routine (version, user, modification date, ...)

How to smooth out discontinuous spacial distribution gradients

Hi all.
I'm controlling a linear motion device, and need to generate displacement paths for it to obey. What I'd like is to smooth out the 'sharp edges' in my profile data (for example, at points where it may go from a slow forward motion to a faster forward motion). Technically, this is removing the discontinuities in the spacial distribution differential, but in other words all I need to do is "smooth my data".
I've mimicked what I want to achieve by putting some hand-created numbers into this graph -->
The yellow line is my original profile data. You can see that I'll be moving the device from position 45 at time 0 to position 52 at time 5 and finally position 53 at time 9. This is fine, but I'd like to smooth out the motion a bit and avoid that nasty elbow at time=5 a bit.
The blue line is what I'd like. A smooth run from position 46 at time 0 to position 53 at 9 seconds, that preserves the velocities (gradients of the profile line) at the beginning and end. The reason for this is that the motor will arrive at position 46 (time 0) at the velocity inferred by the first gradient, and will continue beyond position 53 after time=9 at the speed inferred by the end gradient. Therefore I must not change the gradients of the line at the beginning and end.
I've tried using the many Signal Filtering techniques LabVIEW has available, but I've found that they create problems:
1. They don't preserve the beginning and end gradients, and
2. They tend not to like the very few sample points I have here. (If I interpolote the yellow line to create intermediate points, the filtering works better, but still suffers from point 1)
I've tried using the B-Spline curve fit, but that seems also not to respect the gradients.
I've tried the cubic spline fit, but that doesn't return the extra points I need to create the blue curve the way I've shown here.
Does anyone have any advice? I thought this would be simple, but I'm a bit stuck now but I suspect that there'll be someone out there that's had to do this too.Naively I expected there to be a simple function called "Smooth Data", but clealy not.
Many thanks in advance for any responses received.
Thoric (CLA, CLED, CTD and LabVIEW Champion)

In my copy of Haliday Resnick and Walker there was a note that talked about Einstein and "working in divine issolation" where he was not distracted by others telling what was leagl and what wasn't. I recall that note when I propose idea like the following that some math type will tell me has not physical meaning and dismiss it off-hand. But since I don't limit myself to what is allowed or legal...
See this thread starting a post #5.
Summary:
CC's best attempt at smoothing the curve was shown in this plot.
Using my non-legal technique, I got these results.
I a nutshell:
When yo ufilter you loose data at the front and back-end with the number of points of data loss being determined by the order of the filer. By first pre-pending and appending the same data set reflected about the first and last point, we trick math into telling us what it woudl refuse to tell us otherwise.
maybe this will help you,
Ben
Ben Rayner
I am currently active on.. MainStream Preppers
Rayner's Ridge is under construction

Reduce noise on thermocouple readings on NI PCI-6225

Hello All
I have a problem with what appears to be static electricity induced noise on thermocouples.
We are testing with a sand like medium flowing across a plexiglass window and measuring temperature in the flow. The interaction of the air/sand mixture flowing across the plexiglass creates a significant amount of static and our thermocouple readings are severly impacted. Is there a way to filter the signal so my data and signal analysis tools ignore obvious off-scale readings ?
The filtering i see seems to only apply to high freqency noise. I would like to trim the signals from the TCs to ignore any measurements above 700DegF and below 32Degf.
Thank you
Solved!
Go to Solution.

Hi AeroEng,
It might be helpful to see what the current state of your acquisition VI is - just to get an idea of your overall architecture. I can think of a couple of alternatives.
You could do some external signal filtering to get rid of the extra charge on your thermocouple wires - refer to this very helpful White Paper on the topic of Wiring: http://www.ni.com/white-paper/3344/en/
As far as software-defined filtering, you could use the In Range and Coerce function (http://zone.ni.com/reference/en-XX/help/371361J-01/glang/in_range_and_coerce/) on your data and use the boolean output to hide your actual data or simply coerce it to your MAX/MIN values
Hopefully this helps!
Xavier
Applications Engineering Specialist
National Instruments

Need help about Hidden Markov Model model

I want to make classification for EEG signal using Hidden Markov Model
algorithm based on neural network.
plz need help about how to implement this algorithm using LABVIEW.
if not I want another thing to make classification.
any one know information about this topic, send me a reply
thanks

Have you derrived the HMM that you want to implement?
If so, post the algorithm and we can provide comments on how to implement it using LabVIEW.
Message Edited by Ray.R on 04-12-2010 12:54 PM

How to filter data in defining request

Hi Midhun,
Could you please help me in filtering data in defining request in offline mode.
Still I am trying to open the store and read the data from store I am getting 0 records read from the store
Best Regards
Abhinav Dodda

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
V-F
Attachments:
filtered 0,9999.JPG ‏186 KB
non filtered.JPG ‏185 KB
filtered 0,9999999.JPG ‏189 KB

How to filter data in Graphs?

Hi,
i want to filter data in graph. can anyone provide me links or information how to put filters as well as sorting.
Thanks,
Lax

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
V-F
Attachments:
filtered 0,9999.JPG ‏186 KB
non filtered.JPG ‏185 KB
filtered 0,9999999.JPG ‏189 KB

EEG signal filteration

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