Peak detection/DAQ
Hi! I am new in LabView.
I try to solve a problem with a peak detection in signal. I use BNC-2110.
This is my input signal - graph above show just digitized signal, and graph under - signal with "mean".
I have found 2 suitable .VI. They found peaks, but in simulate signal. I have try to change this program for using DAQ-Date as input signal. But it was not successful, I have become many errors etc.
Can you advise me, where is a problem?
With best regards, Alex
Attachments:
Signal.PNG 78 KB
Peaks_ermitteln2.vi 49 KB
peakxmpl.llb 40 KB
I now about this peak detectors, but they show very many peaks instead of 1
And in this Program (peaks_ermittlen) it was very good realized. But I don't understand, how can I change the type of Input Signal.
In this pic I have to draw, what i measure must - Time between 2 peaks
With best regards, Alex
Attachments:
Unbenannt.PNG 48 KB
Similar Messages
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Peak detection( take 100 ms samples?)
Hi...
I have a problem using peak detection under Analysis=>waveform monitoring.
I want to get the real data (ECG data), and detect the peak of the data. Then i want to store the index of the peak into array so that i can measure the time difference between two peaks.
my problem is that when i use peak detection, i cannot get the result as above mentioned. Before this i have tried to test the peak detector and found that if it will detect the peak for 100 ms time interval only. SO if i have waveform with f=100 Hz, then it will detect only 10 peaks..Is it correct that this vi takes 100 ms sample for detection? *correct me if i'm wrong
And since i want to get the real data from ECG hardware, is there any method to measure index of the occurence of all peaks and store it into array? (not only for 100 ms)
-I saw the formula in peak detector help :
To view the locations in terms of time, use the following equation.
Time Locations[i] = t0 + dt*Locations[i]
What does [i] here represent?
Thanks for the help...
Regards,
Rismi *newbie...:dHi...
Thanks, now i can understand about peak detection for simulate signal...
Then if i use this vi to detect peak of ECG data(data from DAQ or recorded data)..This vi will detect the locations of peak of current block of data. what "current block of data" in this case represents..??
i attach my simple program to detect the index of peak of my data. But i cannot get my desired result. And when i detect the number of the peak, the values is either 0 or 1. I don't know how to fix this problems.Can anyone give me advice?
Attachments:
retrieveSunday22.vi 161 KB -
Hey guys.
I have a problem with my peak detect on a Power spectrum signal. from http://www.ni.com/white-paper/4278/en/ I know that
I would like to have f = 1 meaning that the frequency at which the acquired time-domain signal was sampled (Fs) has to be equal to the number of points in the acquired time-domain signal (N).
When i try to do this the peak detect returns the error 20013 the width must be greater than zero and smaller than sample rate.
this makes no sens to me ?
When i have Fs = N x 10 it runs.
I have added the VI that i have problems with ! if you need the whole project I will gladly add that to.
Attachments:
Both sensors.zip 329 KBHi Genex,
instead of that huge VI you should attach a smaller one, that demonstrates the problem! Right now we would need your DAQ setup to generate a signal to be able to try that VI...
So please:
Generate some typical waveforms, make them default in a waveform control and attach a VI with those waveforms and a typical call (with all your parameters) of PeakDetector!
Best regards,
GerdW
CLAD, using 2009SP1 + LV2011SP1 + LV2014SP1 on WinXP+Win7+cRIO
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Calculating BPM using either Peak Detection point by point or FFT
Hi Guys
Im new to Labview and have absolutely no idea on programming and stuff. Im doing a project on Heart Rate monitor.
I'm using labview to read the analog input to an Arduino Mini. In my attached VI im using Peak Detection Point by point to calculate the BPM but it doesnt seem to work. I took references from several VIs to arrive at my VI.
My instructor told me I could try using FFT to calculate the BPM as well but Im not sure how to carry it out in Labview.
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Thanks alot!
Attachments:
heart signal.jpg 43 KB
Heart Monitor.vi 24 KBOk, we have some problems here.
1. The Data Bits property is the number bits for a single character that is being transmitted. You should not use that. Since you are using an Arduino, it should be sending the termination character. So just tell the VISA Read to read maximum number of bytes you expect from a single message or just some large number (like 25). The VISA Read will stop reading the port when it encounters the termination character.
2. The String Subset is not doing anything. Just remove it.
3. You should move your Wait to be outside of the case structure. As is currently written, if you are not taking readings you will use up all of your CPU.
4. You should have labels for all of your controls and indicators.
5. Your time calculation is completely wrong. You want to subtract the time of the previous peak from the current peak. I recommend you use a Feedback Node to do this.
Here's a slightly cleaned up version of your code.
There are only two ways to tell somebody thanks: Kudos and Marked Solutions
Unofficial Forum Rules and Guidelines
Attachments:
Heart Monitor_BD.png 42 KB -
Peak Detection and Display of TDMS file of 4 channels
The Peak Detection and Display sample VI in the NI Example finder is exactly what I am looking for but I would like to use a recoded TDMS file as its input. The TDMS file is a 4 channel data file.
Does someone have an example code on how to do this?
ERBHi
I found an example in exampler finder called Read Channel Groups (TDMS).vi, which seems to plot data for four channels written in a TDMS file.
Its also attached.
Kind Regards,
Kind Regards
James Hillman
Applications Engineer 2008 to 2009 National Instruments UK & Ireland
Loughborough University UK - 2006 to 2011
Remember Kudos those who help!
Attachments:
Read Channel Groups (TDMS) forum.vi 20 KB -
Peak detection in certain frequency
Hello everyone.
I am a rookie of labview, and I want to realize a program.
The program reads in data and then do FFT transform.
After getting FFT waveform, I want to search the waveform for peak in certain frequency, say 0.4~0.6Hz,
and then output its magnitude.
I have done the FFT part, but I have no idea about peak detection in certain frequency.
Please help me! Thanks!Isnt this what you want ?
Regards
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Institute of Avionics and Aeronautics
" Its never too late to be, what u want to be"
Using LabVIEW 8.2
Attachments:
FFT min max.vi 111 KB -
How to use peak detection in labview to detect peaks from data acquisition information
Hi
I am a university engineering student who is working in a team to develop a coin detector, its purpose is to recognize different coinage and detect fakes.
For this we are using LabVIEW 8.5.1. I am relatively new to labview and have had no experience of using to before. We are trying to integrate four voltage signals produced by an electromagnet, straingauge, optical sensor and a proximity sensor. We have already developed signal conditioning for these tests and now wish to put them into labview.
Our plan is to use peak detection on each of the tests so that labview can detect peaks which correspond to different coin types, provided they meet set criteria for each coin. Then to combine these either using logic or mathscript to produce a Boolean output for each coin.
One of our advisors helped us develop a peak detection program for a simple simulated sine wave however we are struggling to adapt this for data acquisition information and itegrate it with mathscript and to be honest it does not make much sense. I have attached the program below. Thanks in advance for your assistance.
Attachments:
Strain 2.vi 25 KBChris,
Here are several ways to help you get started with peak detection:
1. On your functions palette, you can search for "peak detect" and you'll find several different variations of VIs that will do peak detection.
2. You may also want to take a look at this tutorial: Peak Detection Using LabVIEW and Measurement Studio
3. There's an example in the example finder called "Peak detection and display" that will probably be useful.
Hope this helps,
Misha -
6i can't find waveform peak detection vi. Load error code 20
6i can't find waveform peak detection vi. Load error code 20
The waveform peak detection VI is found only in the Full and Professional development systems. Do you have the base package?
-
Fetch and peak detection all channels of PXI-5105 with 4M record... HELP!
Dear collegaues!
Please help me to improve performance my application, see attachment, and sorry for my English.
So, my task is to fetch and peak detection all (eight) channels of PXI-5105 with 4M record and sample rate 4M with loop 1 sec...
Inputs of all my channels are wiring to NaI detectors with 0,5...1 microsec of pulse width (really) and freq from 0 kHz to no more than 40 kHz.
Why I've selected 4M record and 4M sample rate namely? Answer is that I've tested PXI-5105 previously by generator 40 kHz and 0,5 microsec width pulse. It is working fine and peak detection indicate for me 40000 pulses/sec. If I set lower than 4M record and 4M sample rate it is no working. In my honest opinion 4M record and 4M sample rate are very min settings.
In the present time peak detection working only 6 channels... When I've connected to diagram more than 6 "peak detector.vi" - I see the error "...out of memory...".
Please advise me, what is to be done for that is all working fine.
Solved!
Go to Solution.
Attachments:
consumer-producer7.vi 44 KBWhat you are running into is an out of memory error in LabVIEW. You have enough onboard memory to capture 4M samples per channel on the digitizer. The issue is with fetching and manipulating that data in your LabVIEW application. You will want to step back and take a look at how you are handling your data to understand why that is happening.
1) 4M samples/ch = 4M Samples x 2Bytes/sample/ch = 8M Bytes/ch
2) Expanding to 8 channels creates 64M Bytes of data in the raw binary format
3) You are scaling your data by fetching in a 1D WDT format. This stores each sample in a 32 bit double, expanding the memory to 256M Bytes (in addition to timing information)
4) By splitting up the array of waveforms and branching data it you can easily create copies of this data, and if your consumer loop is not completed with the last data, you may be trying to capture a whole new set, creating yet another copy.
So you can see that while you have 1.5GB of controller memory, when dealing with large arrays of data you can easily eat up that memory. There are several things you can try to make your application more efficient. You could work with an unscaled binary data format, you can wire the array of waveform directly to the peak detect vi (instead of creating 8 copies, you will have a single copy with arrays of output) or you could revisit the record size you have chosen (experimenting with your threshold and width settings might help you to get the results you want with smaller record lengths).
-Jennifer O. -
Looking for function or vi to calculate 1/2 power points of data obtained from peak detection vi
I am analyzing vibration data and need a function or vi that will operate on peak data returned from the LabView Peak detection function and provides 1/2 power points or sideband frequencies. These are needed to compute a "Q" factor. So far I have not been able to find anything.
Thanks, FranThe sound and vibration toolset may help here. there are several vibration level measurements including peak. With the advanced FFT functions in the Sound and Vibration tools, the zoom FFT can be used to identify and find sidebands and associated amplitudes.
here is a link to the manual
http://digital.ni.com/manuals.nsf/websearch/1F8691E94728BDF5862570490058C3B2
here is a link to the toolset
http://sine.ni.com/nips/cds/view/p/lang/en/nid/10521
please note the bullets on the above page (about half way down) noting peak detection, etc.
Preston Johnson
Principal Sales Engineer
Condition Monitoring Systems
Vibration Analyst III - www.vibinst.org, www.mobiusinstitute.com
National Instruments
[email protected]
www.ni.com/mcm
www.ni.com/soundandvibration
www.ni.com/biganalogdata
512-683-5444 -
Hi,
I have plotted the spectral data in XY graph indicator using a .txt file. Now I need to detect the peaks present in this spectrum, their locations and amplitude. I have used Peak Detector .vi in the code. However, it is not generating relevant peaks but displaying approximated values with wrong locations(x values). Is there a better and accurate way to detect the peaks? Please refer attachments for the code.
Let me know.
Thank you.
Attachments:
data1.txt 28 KB
read_spectrum_1.vi 62 KBHave you read the LabVIEW Help file (when looking at the BD, type Ctrl-H, then go to the "Detailed help" at the bottom of the popup) about the peak detection function?
"Locations contains the index locations of all peaks or valleys detected in the current block of data. Because the peak detection algorithm uses a quadratic fit to find the peaks, it actually interpolates between the data points. Therefore, the indexes are not integers. In other words, the peaks found are not necessarily actual points in the input data but may be at fractions of an index and at amplitudes not found in the input array.
To view the locations in terms of time, use the following equation.
Time Locations[i] = t0 + dt*Locations[i] ...
... This Peak Detector VI is based on an algorithm that fits a quadratic polynomial to sequential groups of data points. The number of data points used in the fit is specified by width."
Your input data is so noisy that getting as results the actual points from this function that visually seem to be "peaks" is virtually impossible. Not to mention that there is such an offset at the begining of the data that you are getting gazillions of false positives here. You really need to clean things up before you let LabVIEW loose (at least the Peak Detector VI) on it if you want meaningful answers.
BTW, setting "the threshold slightly below [7379.18]" would not necessarily result in a peak depending on your definition of "slightly," because your data has no points below 180.041, making the highest possible peak 7199.139.
Cameron
To err is human, but to really foul it up requires a computer.
The optimist believes we are in the best of all possible worlds - the pessimist fears this is true.
Profanity is the one language all programmers know best.
An expert is someone who has made all the possible mistakes.
To learn something about LabVIEW at no extra cost, work the online LabVIEW tutorial(s):
LabVIEW Unit 1 - Getting Started
Learn to Use LabVIEW with MyDAQ -
Hi All,
I am looking at implementing or using the peak detection function in C. I require the same in C since, I would be later porting this application on microcontroller.
However, the function implemented in LabVIEW calls the lvanlys.dll for performing the peak or valley detection. Hence, I would not be in position to use the same and later port it on the controller.
Essentially I am looking for similar function inputs (threshold and width) implemented in C.
Thanks in advance.
Regards.http://www.nr.com/
http://en.wikipedia.org/wiki/Numerical_Recipes
Numerical Recipes in C. The Art of Scientific Computing, 2nd Edition, 1992, ISBN 0-521-43108-5.
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' -
Peak Detection with Base package
Hello,
I'm constrained by a budget so I can't purchase the analysis package
just for peak detection. Does anyone have any hints on how to search a
1-D array for peaks without using the pre-made VI's? I've been pulling
my hair out over this one for a week!
Thanks in advance.Labviewguru wrote in message news:<[email protected]>...
> Jason,
>
> I would suggest looking online for a "peak detection" algorithm.
> There are a number of ways to do it. The LabVIEW peak detector using
> a least squares quadratic fit to find the peaks, with a filter of
> amplitude and width. This can also be done much simpler ways. You
> can try applying a smoothing filter (use a moving or windowed average)
> and then look for peaks that way.
>
> Please post if you need more assistance. Also, what are you trying to
> do with the peak detection. This would be helpful in providing
> further assistance.
>
> Good luck
Labviewguru
Thanks for the advice. Yeah, the NI home page tells me that th
ey use a
least square quadratic fit to find the peaks. I'm not sure on how to
implement that. I'll do a web search on that one. I'm not dealing with
a very noisy signal so I don't think that I need to do a moving
average. The amplitude filter seems pretty easy, I just compare each
point to a preset threshold. However my peaks are composed of more
than one sample so each peak gives me a bunch of "true" values. I only
want one count per peak. The way I thought of doing it was using
hysteresis and starting a subroutine when the upper limit boolean went
hi, then resetting the subroutine when the lower limit boolean went
hi. So essentially i need to have labview look for a high, THEN look
for a low, THEN reset over and over again until the sample array is
finished. I'd love to work on this for days but I've already put too
much thought into it. -
Respected sir/madam,
i am actually processing human radial artery pulse signal... i acquired that signal and linearised that by using filter...
there is a problem in peak amplitude detection and location...by manually we can say there is more number of peaks ..but peak detector shows only 25 peak's amplitude and their locations...i can't understand about locations that shows..i attached the data which is in .lvm extension and the vi
please help me to rectify the problem..
thank you
Attachments:
Untitled 2.vi 100 KB
Untitled 2.vi 100 KBOnce again the Dynamic Data Type (DDT) generated by the Express VIs hides the real problem.
The data segments are too short to reliably detect the peaks - not every segment has a peak and some peaks may be partly in one segment and partly in the next. By combining all the data into one waveform before filtering and peak detecting, it is possible to get reliable matching between the "eyeball" peak detector and the software peak detector.
Note that the large transients at the beginning of the data set are detected as peaks. These transients are due to the real transient in the data and the transients of the filters. I did not attempt to remove them. You could use Array Subset with either manual selection of the end of the transient or some automated process based on the larger amplitude and lower frequency of the transient compared to the real signal.
There is a lot of "stuff" in this VI - things I tried and did not remove and multiple ways of doing things. The enabled diagrm of the Diagram Disable structure has a constant with the data from your file so that I did not need to read and process the file repeatedly while working on the filters and peak detector.
Comments in no particular order regarding what I did and how the posted VI works.
1. The DDT data from Read from Measurement File.vi is converted to an array of waveforms. The Waveform data type is well docmuented and the internal data structure is readliy accessible.
2. Each element of the array of waveforms from Read from Measurement File.vi is appended to the corresponding element from the previous iteration to form one array of waveforms containing all the data in the file. This is displayed on Array of Waveform, Array of Waveform 4, and Signals total. Note that these are graphs, not charts. The data is also put into 2D arrays as Array of Waveform 2 and Array of Waveform 3.
3. I do not have Advanced Peak Detector PtByPt.vi, but I think the data is not truly point by point so this may be a poor choice.
4. I used the standard filter VIs (rather than Express VIs) to stay away from DDT. The outputs are slightly different, but the Express VIs do not give you complete control or knowledge of what the filter setup is. I used Butterworth filters for both filters and adjusted the cutoff frequencies slightly to get similar waveforms.
5. I used the standard Peak Detector.vi from the Signal Processing >> Signal Operations palette. It reliably finds 104 peaks over a wide range of widths and some variation in thresholds. That count includes the transients at the beginning as mentioned above.
The .2 VI contains all the junk code I described above. The .3 VI is a cleaned up version.
Lynn
Attachments:
Untitled 2-9.2.vi 760 KB
Untitled 2-9.3.vi 183 KB -
Waveform peak detection ...Please have a look
Hi folks,
I am trying to acquire 2 signals and then detect the peaks of each of them and divide the peaks and display it in a waveform chart.But my Peak detection doesnt work at all...I tried plugging in values from 3 to 10000 but it just doesnt work...Please have a look at my VI and feel free to point out any errors in my VI..
Thanks
Attachments:
slope 2 channels3.vi 51 KBHi,
Had a look at ur VI
tell me, do u need a single peak for every iteration or a series of peaks above a certain threshold?
If it is a single peak for each acquired waveform , then extract y array from the waveform cluster( you have already done it in ur VI) and connect it to 'find array min max' function found in array functions palette and u get the single peak for each waveform.
If it is a series of peaks u are interested in, then compare all these values inside a for loop.
Index each element inside a 'for' loop, check it for threshold using a conditional case structure and put it inside a shift register.
regards
Dev
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