Peak detector

Similar Questions

• FWHM with peak detector

  Hello

  I know that I write a question that has been asked many times before, but looking through the answers to these questions, I was unable to find a solution that worked for my case. Joined a VI for reading data (much like a chromatogram), I need to be able to use to find the FWHM of any pic that appears in the show to analyze. I have also included a data file containing a single peak. A previous post had mentioned using the detect.vi tip and a function of the square root to find the half widths, but it returned a false value when I tried this concept. I have a similar program I can run in Excel in order to give me the FWHM, find the vertices, find four data points nearest you up from half and interpolating these to find the values at the exact half max. However, being new LabView, I don't know how to program this function. Any help would be greatly appreciated.

  <><>

  You can try to use the 'threshold 1 d table' VI.  Find you tip the table max/min function, index Max to the max and then find in the table for the next value of 1/2 max.  The index of this value will be half of the total width of the CIP index and could be multiplied by two to give the entire width.  If the pic is not symmetric, then "Reverse the 1 d table" and seek the point of peak 1/2 from your pic again.

  The difference between the threshold of two points should be the width of the points a half Magnitude.

  Hope that helps.

  Good grief... spelling is terrible.

• location in the Ridge detector indicator

  I went through the context help for peak detector. I force understand the importance of the location indicator. Can someone give detailed information on how to find places of any input signal. ?

  If my proposal here:

  

  If you have another type of Signal, describe it or show it.

• Detect the PEAK, mount and average

  I use a loop in LabVIEW 8.5 to capture the signals emitted continuously by a card, peak detector.VI is used to detect the signal peaks, then fit.VI nonlinear curve is used to climb the summits, signal now capture, detection of peaks, mount and display pics are all works very well permanently, but there are still some problems annoying me.
  1. the received signals is not very stable, so editing results expected on average for 100 times, then how can I averaged the results of fitting on the condition that the capture of signal is not interrupted, this is the time loop does not stop, when the average is made this time, average is reset for the next 100 fitting results can be average again?
  2. There is another way, that's 100 results of fitting is automatically saved to excel, then the results is an average manually in excel, then how to store results like this: the first 100 results of connection are stored in an excel file and the next 100 results for other excel connector or they are stored in an excell , but in different columns? Of course the thses are subject to the capture of signal is not interrupted.
  3. There is a threshold for the detector.VI peak, but the captured signals entry isn't very stable, so the number of peaks detected is not the same every time, like this time, the number of vertices is 40, next will be 39, this will affect the results of fitting slightly, then how do to detect the same number of vertices every time such as the number is 40 each time?

  Any advice will be appreciated!

  Maybe the pic attached detect.vi 'test' can help you. "medium signal.vi" is a sub VI on average the signal in a way online.

  There are three methods using the input signal:

  1. no average.

  2. average exponential.

  3. linear average.

  Your problem is when the input signal is damaged by some noise, and you want the input signal before the detection of peaks on average. I use white noise to simulate a noisy environment.

  By default, the average mode is 'Linear', and the number of averages is 50. The more averages, the best on the result, but more time to update.

  Swith mode between 'Linear' and 'No way' to compare the difference before average and average.

  Average exponential is not appropriate in your case.

  Let me know if it works for you.

• LabVIEW Ridge detector - fails the simple test?

  Hi people.

  I tried two different spectra for the LabVIEW waveform peak detector (LabVIEW 8.5).  It works fine, the other not, and I'm trying to understand why.  VI and attached screenshot.  I've hardcoded the bays so you can just run the VI.  Any thoughts?

  

  Thank you

  Don

  Hi Don,

  Seems to me that the values are all simply too weak.  But it's weird that there is no error generated.

  I don't know if this solution will work for you or not.  But I tried something on a whim and it seems to work.

  

  The only thing I can guess is that the numbers that you were simply too small for the algorithm to work.

• The envelope of the beat (coupled pendulum)

  Dear members,

  With my USB6008 I measure the position of coupled pendulums. Fortunately, it works very well.

  But I want to create the envelope of my measured of the curve (see photo).

  I tried to do it with the help of the Butterworth filter VI and VI of peak detector.

  All I got is the first part of the red line, then the black line. But I want to have the whole line is like the red line (see for example also here https://de.wikipedia.org/wiki/Dateiine_envelope.svg).

  Attached is my measured data. I would be very grateful if any of you can help me solve this problem!

  
  

• How to find the crest of a curve of best polynomial form

  Hello

  I'm relatively new to Labview.  I need to find the value of x corresponding to the maximum value of a better curve adjusted to a set of values there.

  A typical dataset that I will work with is a table of about 15-30 y-values that are equal distance from known x-values (I have attached a file .lvm for an example of values y and x values), and it will be a fairly well-defined Summit.

  The way that I do currently is to use the curve express vi, with a polynomial curve of 10 order, and then by converting the best adjustment line to an array of values using array Max vi Index to find the peak value y and wiring its index in a table of x values to find the position corresponding to the peak. I enclose my vi that does this.

  The problem with this method is that I can't get the accuracy I need (because the values of x are spaced by 0.15, I wish that the precision of about 0.01).

  I also tried out the best integrate a node formula coefficients (from the curve express vi) and then run a loop of x than aircraft values more accurate data points, but I had trouble getting the curve of this method to match the better to express vi curve curve.

  Do you have any suggestions?

  Call it what you want, but you're smoothing or filtering your data.  It will pass the height and location of your apparent peak.  Instead of trying to fit all of the data, you must use a mobile window where you set a subset of the points to a polynomial and check for a pic.  That's exactly what the Ridge detector VI.  I'd like to see if this VI - what are looking for before you go through the gymnastics of the polynomial.  In my example, I remove the maximum amplitude peak and find its location.  The location returned by the peak detector is a fractional index, so you can use interpolation 1 table D to find the corresponding x position.  If you stay with the polynomial in the form, discover all of the polynomials screws, they are a snap to find the zeros of the derivative and other.

  

  BTW, unless you really know the underlying model for your data I personally would be questionable estimates of precision that are 1/15th of the point spacing. 1/3 or 0.05 he pushes IMO.

  Edit: 1 K apparently.

• How to separate data in 'several Information.vi tone "?

  NOTE: I have another post on this subject. Here is the link.
  -----------------------------------------------------------------------------------

  My ultimate goal is to get/display of the frequency at which the peaks that passes.

  I've used different methods (vi is attached) but does not own.

  1 table of Max and Min > it only shows Max amplitude but not all orders of magnitude and not the frequencies at which the peaks that passes. I guess I should somehow use a search function in a loop or something, but I have no idea how to do that.

  2 peak detector of. VI > This method was good for the summits, but not the frequency. It shows the indexes that are double. If I multiply them by 10, it gives me the frequency and I don't know why?

  3. several information.vi tone > This method has the advantage of threshold, but it's the combination of the cluster and the table which I don't know how it unbundle and get the frequency. Another problem is that it shows only a single tip and its frequency to the not all same time as I develop the table.

  Thank you

  I have change your dynamic waveform data. Extract several tone Information.vi works better now.

  This function need a waveform as input.

  Concerning

• How to index a table on multiple sites?

  Hello

  How to index a table on multiple sites?

  I searched this issue and was not able to find the answer. I understand that it can be done with loops, but I don't know how.

  I use the detector of crete vi for frequency domain data collected a VNA (s2p) file. The products contain a table of amplitudes and a table of locations. The problem is that the locations refer to the index of table of amplitude, which is not the same as the frequency. My idea is that I can use this output of the places table to index the frequency to the detected peak frequencies table and then draw these, as well as some analysis data and manipulation on them. Currently, I can do this only by consulting table on the front panel.

  The entrance to the peak detector is currently a table 1 d of the scale (what is the problem?).

  I also looked at the supply frequency & estimate VI, but this VI seems only exit of scalar data for the largest peak, not exactly what I'm looking for.

  Thanks for your help.

  You have a second table for the tested frequency?  If so, then you are right that you just need to index this table with the indexes by the Ridge detector.  Use a loop for.  Automatic index to the index, use index in array to get the value of the frequency and autoindex on frequencies.

  

• Reading USB-6008/DAQmx sampling

  I use LabVIEW Student Edition 2009 with an acquisition of data USB-6008 on a Windows 7 computer.  I must confess that I am rather self-taught in LabVIEW and may lack in fundamentals.

  I wrote a code to move motor back with a sine wave with the 'Signal to simulate"VI and VI"DAQmx Write. "  I think that this part of the code is OK but its probably sloppy.

  The part that that concerns me is the "DAQmx Read" part - I use this to get a feedback of the motor position on an analog scale 0 - 5V via the port of AI1.  I also use this DAQmx Read to get another feedback voltage from a force sensor that feels the force in a piece of material set by the engine.  I want the information to all-terrain such as graphs or tables with the last 30 seconds, and then a value of information, but that's all I want to see since this cycle repeats for hours.  I also need to process this information - if the strength of the material gets high, I need to stretch less etc.  So far, everything is working fine, but now I want to use the "peak detector" VI for expressly that the "peak" of the sine wave is part of a certain range of strength and the '' Valley '' falls into a second range of force and clearly since I read this information as a single integer/sample there is no 'memory' of the last seconds in the form of a table of examples past or a waveform or something like that I can't detect the peaks.

  So my question is - should be sampling this information differently to temporarily store information (such as a waveform or something?) or should I use individual samples to build a continuous array for the last 30 seconds?  In other words, what is the best way to read this information in a way that will make it easy to detect the peaks on the final seconds, but not to store hours of endlessly repeated information?  I also want the release of LabVIEW and feedback from the system graphics to match so that the signal sent to the engine for the same positional signal back to LabVIEW from the engine.  I should add that I do not know if the system works in real time or on a little late, but nothing like over delay of 30 seconds.

  I have attached a code that I use to calibrate my system - is not the same as I mentioned earlier, but things 'DAQ read' are the same and you get the idea with the rest of it.  I can also reach more detailed code if it would help.

  Yet once again, I'm sorry for my skills of coding bush-league and thanks for any help!

  -Chris

  If you always use a waveform chart to display your data and your happy with length of time of the chart, you can use the 'Historical data' property node for recover your data from 'short term' gathered.  From there, you take the data and make a type of waveform data using the 'build' primitive waveform.

• Ridge detector does not properly

  The Ridge detector not give me the right places. The main file is called activation time. I use the probe but cannot understand why im getting the wrong places. Thank you in advance.

  Your Ridge detector seems to work just for me.  I rewrote the vi to make summits that were detected more easy to see.  You put them all into a 2D array, which resulted in many many zeros.  I have grouped the data in a table of clusters.  Each cluster contained a table of the peaks for each line.

• Ridge detector malfunctioned.

  Hello

  I'm working on a project in which I want to calculate the rate of certain signals. I used the Ridge detector to detect the peak of the wave.

  The Ridge detector works properly, but after some time as 40 seconds it starts counting the noise (which is less than the value of the Amplitude, and which was previously not count), I don't know the reason for it.

  Can someone pls help me solve this problem

  Thank you v.much

  Hello

  Finally working on the first vi I found the solution to my problem

  The reason why I got for the evolution of the value of the rate was this picture filled, i.e. with time, the table gets more and more values and he took the time to work on it and therefore the vi give erroneous results in the rate.

  I finally limited the value of the table and then past this range limited to the consumers section of producer for the calculation and then it worked correctly.

  I ask everyone to answer me if I took the right path for the solution.

  Thanks to all who have helped me get a solution.

  Concerning

• Plotting the amplitude of a spectral peak over time

  Hello

  I am creating a VI where the acquired continuously DAQ, plots and save a waveform in millisecond delay (which is already done in this case), then takes this waveform, finds a specific pic (probably the first) and trace the amplitude of this pic over time (+ 30 minutes, one point each scan which is obtained). Essentially, I have a detector quickly attached to a chromatograph, and I want to select a single ion and monitor the amplitude of this ion. I can draw the waveforms along with it in post processing, but I want to do is to have the 'slow' constantly plot to update and display when it moves through time. Joined the VI will go in, using IMS software V1.3.vi, the paragraph is the "GC" Mode it seems I should use the "peak detect.vi.", but I'm not familiar with this operation, and so I don't know how to show a constantly updated graphic or remove the amplitudes and draw. Thank you for your help,

  <><>

  Eric-WSU wrote:

  I get an amplitude on plot of time, but it does not appear until after all the iterations are stopped

  I have not watched your VI (because I'm in a previous version of LabVIEW), but it's probably because your graphic is outside the loop.

  Here's how you can get a graph of the peaks (all vertices, by iteration):

  

  Or if you want to only a certain PEAK (and how this pic changes with the number of iterations):

  

• detection of peak with two thresholds

  Dear colleagues!

  Excuse me, but I need example or any help for the detection of peaks with two thresholds. Namely two adjustable thresholds with detector standard Ridge for the creation of a detection bandwidth or range.

  Detector of crete have only one threshold of... But why only one...

  
  

• Input analog continuous USB DAQ find amplitude peak to peak

  I need to know if there is a way to use the crest detector when you do an analog voltage input. I use c# VS2005 and 8.6.

  Hi jsheridan,

  Have you looked at the Ridge detector example that comes with Measurement Studio?  The c# example can be found here: C:\Documents and Settings\All Users\Documents\National Instruments\MStudioVS2005\DotNET\Examples\Analysis\PeakDetector\cs (assuming that you have installed on your C drive :).

  The example generates a waveform and uses the PeakDetector class to detect the peaks.  You can take this example and modify it to support what you are doing, or just put some functions in your code.  The detector function takes an array and outputs tables of places, the amplitudes and the second derivatives of the peaks and valleys in the array passed to it.  If you prefer to use all the time, you could just do a ridge detection after each reading some or all few seconds so that you make a lot of unnecessary calculations.