Power spectrum averaging

I am performing a power spectrum and averaging over a number of spectrums.  In addition to saving the average power values for the spectrum, I would like to save standard deviation, max, min.  Is there a way to do this?  It seems that in the Power Spectrum dialog box there is only the option to turn on averaging, but not to save this other data.

Hi,
Hoe do you want to save the data (format)?
If you want you can save the value as txt numeric data in spredsheet file.
Or do you have any other idea
Regards

Similar Messages

  • Convert power spectrum back to original waveform

    Hi,
    I have program my PXI 5610 to transmit a sine wave to my PXI 5600.
    But when I use the 'ni5660 Read Averaged Power Spectrum VI' to read the signal, it comes out as a power spectrum.. So how can I convert this power spectrum back into my sine wave to show it on the graph.
    I am new into this field, hopefully someone can help me out.
    Thanks.
    Jieyi
    Attachments:
    wiring.GIF ‏9 KB

    Hello Jieyi,
    When you read your signal as spectrum, you loose the phase data. You can still get your signal back but it would not have any information about the phase. I would suggest you acquire the time domain data. This is very simple since the driver can do everything for you.
    The time domain data will be automatically converted to In Phase (I) and Quadrature Phase (Q) which are two components that changes the carrier. You can read more about IQ signals here.
    Then, you can open the example called ni5660 Getting Started IQ.vi located under "\LabVIEW 8.x\examples\instr\ni5660" and look at this:
    Finally, if you have modulation toolkit, you can open any modulation example to transmit a sinewave. These are located at:
    "\LabVIEW 8.x\examples\Modulation\RFSG examples"
    For example, AM:
    Transmitter (Tx)
    MT RFSG Generate AM.vi
    Receiver (Rx)
    MT ni5660 Demodulate AM.vi
    These examples are ready to transmit any standard waveform including your sinewave.
    Hope these information helps,
    Message Edited by Yardov on 08-17-2007 06:50 PM
    Gerardo O.
    RF Systems Engineering
    National Instruments
    Attachments:
    acquire time domain signals.JPG ‏46 KB

  • Power Spectrum with RFSA

    Hi all,
    I have some question about fetching power spectrum with RFSA drivers.
    when i set span and resolution bandwidth as 100M and 1M respective in ni5660 Configure for Spectrum,and use ni5660 Read Averaged Power Spectrum to fetch the power spectrum,does averaged power spectrum output the 100M signal once?
    if so,how can i draw the spectrum in Waveform Chart as RFSA demo show us?RFSA demo did use Waveform Chart to draw spectrum,did't it?
    Thanks
    Liu Yuan

    Hello Liu Yuan,
    If you take a look at ni5660 Power in Band example in the LabView Example Finder ( Help -> Find Examples ), you will notice it uses a Waveform Graph.  The Read Averaged Power Spectrum vi is contained within a while loop which means that it will continuously output the averaged power spectrum.  If you want to use the RFSA drivers, I suggest looking at the RFSA Getting Started Spectrum example in the example finder.  This example only reads the spectrum once, but you could put a while loop around the read vi to get continuous spectrum output.  If you have any more questions feel free to post back.
    Regards,
    Benjamin Cook

  • Power Spectrum vi

    Hi,
    Can anaybody tell me the maximum size of an array that can be accepted by
    the Power Spectrum vi in the signal processing toolset?
    I find that it does not produce an output if an array size of over 5 million
    elemnts is used, however it produces the required output when the an input
    array of 4 million elemnts is used.
    Additionally, when an array of 5 million element and over is used as the
    input:
    1. No error message is produced.
    2. This occurs even when averaging is activated.
    Thanks,
    Luca

    I am not sure which VI you were using exactly. Is Power Spectrum.vi on the palette Function>>Analyze>>SIgnal Processing>>Frequency Domain? I have tried this VI and do not have the problem you mentioned.
    Would you attach some testing VIs?

  • Keeping Power Spectrum Peaks on a Graph

    Hello,
    I am trying to read in a signal which varies in frequency as time progresses. I am taking this function and running a real time power spectrum (FFT Power Spectrum.vi) on it. As time goes the peaks move around according to teh frequency which is coming in. What I want to do is to keep the old peaks on the graph as the new peaks come in. So for example if I had a signal which was at 50 htz then 75 htz, at the end of the run I want to see both peaks on my grpah. Is this possible? Thanks.
    Intern NSWCCD Carderock.

    If you use the Spectral Measurements Express VI, you can configure it to do peak hold. In the configuration screen, turn averaging on, click on the Peak Hold radio button, and set the averaging number to 1. Then all your peaks will be displayed as they come and go. See attached vi. If you want to see how the express vi does it, you can convert the express vi to a normal vi and then look into the block diagram. I believe one of the functions has a peak hold input.
    - tbob
    Inventor of the WORM Global
    Attachments:
    SpectralMeasure.vi ‏98 KB

  • Save Power Spectrum from ni5660

    I am using ni5660 to capture the power pectrum using "ni5660 Power in Band" example.
    Is it possible to save the power spectrum for later use?  In which format can it be saved?  Is there a VI that will do it for me?
    When I mean the spectrun data I mean the output of "ni5660 Read Averaged Power Spectrum".
    Thanks.

    Hi,
    Using any of the File I/O VIs within LabVIEW should work fine for this.  I have attached an example of how this could be implemented by writing to a binary file.  When streaming data in the way you intend to with this example, the binary file format is recommended because it is more efficient in terms of space than other file formats.  In addition to the modified example I have also attached a sample VI that shows how you can read back the data written to the file and confirm that the spectrum actually was saved.  Let me know if you have any questions.
    Regards,
    Andrew W
    National Instruments
    Attachments:
    ni5660 Power In Band w Binary Write.vi ‏57 KB
    Read Binary.vi ‏243 KB

  • Power Spectrum no longer working correctly after upgrading to 8.0.1

    Recently, I installed Labview 8.0.1 to correct a problem I was experiencing in 8.0.  The installation resolved my problem, but now the Power Spectrum no longer gives the correct result.  My program has not changed other than the update.  I checked my circuit and everything is functioning properly.  Before changing to 8.0.1 the power spectrum peaked at 40Hz and 80Hz,  which was correct, and now it peaks at 0Hz and 10Hz.  On top of everything, the peaks are much higher than they should be.  I expect peaks with a max of 2.5millivolts and now they are 1volt.  I don't understand what is going on. Nothing changed, but the software version.  Can someone please help me? 

    In addtion to Altenbach's comments - 
    I'd recommend trying another VI function to get the power spectrum for
    your signal to see if the behavior is the same.  You can find some
    examples of VIs using the power spectrum functions using the NI Example
    Finder.
    You can go to LabVIEW's Example Finder by going to Help >> Find Examples.
    Then search for FFT. There should be some results that include FFT and
    Power Spectrum Units.vi, Power Spectrum Measurement.vi, Basic Spectral Measurements.vi,  and Spectrum Measurements.vi. Try opening and
    running these examples to see if the VIs are returning the proper
    results.
    Mark Walters
    Application Engineer
    National Instruments

  • Signal-to-Noise ratio from Power Spectrum?

    Hi,
    I have a feeling this is a basic issue but for some reason I'm not getting it.  I hope this forum can help.
    I have a Power Spectrum (freq on the x-axis and power on the y-axis) and I am trying to determine the signal to noist ratio of the rf signal live.
    I am using LV 8.5 and have the spectrum toolkit and am using an RFSA in a PXI chassis.
    Any suggestions?
    Thanks
    - rf curious

    Hi Rf Curious,
    This questions does not have a simple
    answer but let me share my thoughts and you can decide what it makes
    most sense for your application. For signal to noise ratio (SNR) you
    should have ideally the power of the signal and divide it by the power
    of the noise. The problem here is that you are looking at both at the
    same time (rf live signal). Depending of what type of signal is it, you
    can recreate it and substract it from the spectrum (you will need to
    recreate the phase and magnitude and delete it from the phase and
    magnitude of the spectrum). This is normally done with simple signals
    such as a tone.
    If you don't have access to the magnitude and
    phase of the data, and you only see the spectrum, then you will have to
    do things different. You can probably measure the power of the signal
    by measuring the power of the band where the signal is located. Then,
    you can terminate your input and measure the power of the noise of the
    instrument (with same attenuation and RBW settings) and have a rough
    estimate. This method should have better results when S >> N. You
    can also take the adjacent channel (or further) noise reference.
    Finally,
    if your signal has a pretty flat spectrum, then you can only take the
    difference between the noise and the signal since they both have the
    same RBW.
    If by now, you have found other methods, feel free to post your ideas here for any other person that come across this problem.
    Regards,
    Gerardo O.
    RF Systems Engineering
    National Instruments

  • Basic accelerometer-power spectrum readings

    Hi all,
    I'm new to Labview and am trying to create a simple power spectrum logger. I've had a look at multiple tutorials but am stuck getting to places (most of the tutorials require sound and vibration toolkit, are really old and incompatible with Labview 2011 etc). The program I'm trying to do is:
    1) Collect signals from accelerometer (4kS/s)
    2) Generate power spectrum
    3) Save to disk (on board the cRIO)
    My setup is:
    - cRIO 9014
    - NI 9234
    - Labview 2011
    So far, I've managed to get the signal readings (XYZ axis) and merge them, put them into a 'Collector' block and then output them to the power spectrum block. I've very crudely used a 'Time Delay' block to set the sample rate (which I know is probably not accurate, but I cannot figure out how else to do it). I'm having a problem figuring out how to input the sample rate into the collector, which is why my power spectrum is giving me 0 to 0.5Hz (it's likely assuming the sample rate is 1Hz). I've attached my .vi.
    Would someone be able to point me to a tutorial/example/alternative solution? Thank you very much in advance.
    Attachments:
    accelero.vi ‏93 KB

    I think what you want is the CompactRIO vibration data logger.  It does not require the S&V measurement suite, though you will find it very useful. 
    Check this out!
    http://zone.ni.com/devzone/cda/epd/p/id/6388
    It has a waveform acquisition template for the FPGA.  It has a data logging state design. 
    You can see a Video of it working here
    http://www.ni.com/mcm/wind/
    Let us know if this helps. 
    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

  • Save Power spectrum

    Hi
    I would like to save a power spectrum ( about 80000 lines of data) as a file that i can later plot. When i write the cluster (coming out of FFT Powerspewctrum.vi)  to an excel  (excel works only upt o 56000 or something like that, so i can´t use it anyways) or .txt file using the a combination of open -write -close  file i get weird number and letters and not the data i´d like to have. Which data format ( iwould like to make graphs in origin) and vi´s should i use to export the spectrum or is it the best to extract the y-value of the spectrum (magnitude) using the unbundle by name .vi  and export it as txt?
     Thanks for any help

    I believe this is also something i can use for my application, however, when trying to recreate the code in LabVIEW 2011 SP1, the connections between the For Loop and the Close File return an error that the data types are different.The Path wire returns that the source is 1-D array of byte stream file reference with the sink being byte stream file reference. The Error wire returns that the source is 1-D array of cluster of 3 elements with the sink being a cluster of 3 elements.  How would i go about fixing this?
    I plan on using this to write to the file from an accelerometer connected to a NI-9234 c-series module through a cDAQ-9178 usb chasssis.  So my intention is to use this as a subVI to connect the accelerometer signal from the DAQ Assist of another VI.  I am trying to record the spectral data. Attached is the attempt at recreating your code.
    Attachments:
    Save Power Spectrum.vi ‏55 KB

  • Memory leak with Power Spectrum function

    Hi
    I have a memory leak on my application. By observing with the "Desktop Execution Trace Toolkit", the Power Spectrum function (from NI_AALPro.lvlib) seems to have two "Reference leak".
    The first one refers to the function "Open VI reference"; I got around this problem by replacing the "Open VI reference" by an "Initialize" input boolean, but I don't understand the second memory leak.
    Any idea ?
    Thanks...
    (See attachments : Desktop Execution Trace + code)
    LV8.6.1 + Desktop Execution Trace Toolkit 2009
    Same problem with LV2012 + Desktop Execution Trace Toolkit 2012
    Attachments:
    DesktopExecutionTraceToolkit.png ‏82 KB
    MemoryLeakPowerSpectrum.zip ‏7 KB

    Hi Mathilde,
    Thank you for using NI Discussion Forums!
    I reproduce this problem with LV2012 + Desktop Execution Trace Toolkit 2012. I will look further into this.
    Are there many calls of this function in your code? Could it be a problem for you?
    Thank you.
    Regards,
    Audrey_P
    National Instruments France
    #adMrkt{text-align: center;font-size:11px; font-weight: bold;} #adMrkt a {text-decoration: none;} #adMrkt a:hover{font-size: 9px;} #adMrkt a span{display: none;} #adMrkt a:hover span{display: block;}
    Journées techniques : des fondamentaux aux dernières technologies pour la mesure et le contrôle/comm...

  • What is the equation for a Low-Sidelo​be Window Function (in Power Spectrum VI)?

    I am trying to find out what is the equation for the Low Sidelobe Window which is mentioned in the Power Spectrum VI. Hanning second sidelobe is around -32dB of the first. What is that for Low Sidelobe?

    The CWT is not equivalent to the discrete dyadic wavelet transform. In theory, the CWT can compute the wavelet coefficient at any positive real scale and any real shift, while the discrete dyadic wavelet transform only includes the dyadic scales (2,4,8,16...). So the formula used to describe the CWT can be referred to the equation in pp.80 in S. Mallat's book.
    In SPT's implementation, the time interval controls the shift in number of samples. The scales indicate the wavelet coefficients at integer scales 1,2,3,...,"scales" are contained in the output scalogram.
    NISH DSP
    Medical ultrasound and signal processing

  • Need Help related to Power Spectrum of two signal

    Hello Sir, 
    I have two signals of different frequencies but i want to take the FFT power spectrum of both signals at same graph . So for that case i take the FFT power spectrum of both signal indivisualy and after this build the array. so i got the one graph and all the components in same graph. Now
    The problem is that in that graph i want to extract the magnitudes at each frequency, but when i extract the information from final graph it will be the " 1D array of Cluster of 3 Elements" so its information is saprate for these two signal. but i want to tale the magnitude at each frequency , how can i got this sir . Please Help me 
    Agnivesh

    Sir it works thanks but there is one new problem is that wahen i am going to extract the magnitude for every frequency it is also works, but my question is that if my frequency is in floating point then how can i extract magnitude for that frequency. i mean i extracted the magnitude for every frequency component starting from 0 to 1...2..3...4.............so on (Frequency ) but if my frwquency id 2.3Hz so how can i do this.i am sending you my VI also 
    Agnivesh
    Attachments:
    Analysis HP Compressor test 1.vit ‏3485 KB

  • Power Spectrum Density conversion to Time Series Data

    Hi,
    This may seem an odd request but is there a way to convert power spectrum density data back to the time series data that generated it in the first place. I have lost the original time series data but still have the PSD and need the time series to do other analysis.
    Thanks,
    Rhys Williams

    Hate to be the bearer of bad news, but there are an infinite number of time series that will generate a given PSD.  You lose all phase information upon taking the PSD.  For this reason I almost always save time domain data, or at least complex FFT values.  

  • Read Text row by row, plot them and find the max of its Power spectrum

    Hi, everyone,
    I have to read data from a text file, plot as a time serie and find the frequency to its max power spectrum. I found a previous post related to my issue so I revised his example a little bit. But once I decide to store the data into an array, the Labview reported:' Error 1 occurred at Scan From String (arg 1)'. Can anyone help me out?
    Thanks in Advance!
    Gab
    Attachments:
    ReadXYZmine.vi ‏18 KB

    Again my attachment got missed out.
    - Partha
    LabVIEW - Wires that catch bugs!
    Attachments:
    ReadXYZmine_Trim Whitespaces.vi ‏19 KB

Maybe you are looking for