Envelope Of Signal

i want to create envelope of the upper values in my program i don't how to doit could you help me. I read wav files, and i must do Amplitude envelope of my signal
Attachments:
FKG Final Forum.vi ‏164 KB
Heart Sound.zip ‏60 KB

Hi Marcinbyc,
I believe the function you are looking for is "Clip", available in Signal Processing»Point By Point»Signal OperationPtByPt
Hope that helps!
-Sam F, DAQ Marketing Manager
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Similar Messages

Envelope in real-time

Hi,
I want to calculate the envelope of the amplitude of a signal in real-time. Initial testing with the Hilbert transform has been unsatisfactory. I now square the signal, detect the maxima of the squared signal and do an interpolation on these maxima to recover the envelope of the signal. However, this results in an unacceptable delay of 1/2 signal period. How can reliably calculate the envelope a signal in real-time?
Best,
Michiel

Hello Michiel,
I see you tried to implement the Hilbert Transform.. DId you write this your self our did you try an example program? IBellow I put down a link to an example VI which does a Hilbert Transform. Did you see this VI before and does it also not do what you want to achief? The link:
http://zone.ni.com/devzone/cda/epd/p/id/1346
Regards,
RikP - National Instruments Applications Engineering
Rik Prins, CLD
Applications Engineering Specialist Northern Europe, National Instruments
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Récupération d'un courant créé par un champ magnétique

Hello i need some help to realise a program on labview. I will ask my question in two languages (French and english) Excuse me for my english, it's very bad.
To explain precisely, i want to recover a signal from a coil.
I send a current in this coil (the coil who surround a sample ) and i stop the current to study the answer create by the oscillation of the magnet field.
To explain when i stop to send the current in my coil the nuclear magnetization precesses about the earth's field induces an alternatiting voltage in the same coil at a frequency of about 2kc./s. which i want to observed after suitable amplification.
For it i use le NI 6009 and Labview 8.
I want too recover this signal and after detect when the signal was almost equal to 0. At this time i want to send a burst to maintain my signal.
So the green signal is the polarising signal. When i stop the green signal the field cames back and it creat the black signal. When the signal is equal to 0 (+-5%) i want to do a burst ( red signal) .
To conclude i want to recover the envelop of the signal.
So my questions are :
How to detect when the signal is equal to 0 (+-5%) and send a burst ?
How to create a burst with the same frequency of the black's signal ?
How to recover the envelop of the black's signal (=blue's signal) .
Thank you for helping me and excuse me for my english. I'll try to better, i promise.
Et en français ça va être beaucoup plus facile. Donc j'aimerai visualiser un courant créé par le retour à la normale du champ magnetique. Pour expliquer plus précisement, je créé un champ magnétique perpendiculaire au champ terrestre dans une bobine qui entoure un echantillon. Quand je stop le courant de polarisation vert, le champ magnétique reviens à la normale dans le même sens que le champ magnétique réél. Si l'on observe le courant on obtient la courbe sinusidale décroissante que j'entretien avec un burst ou impulsion qui correspond à un signal sinusoidal de fréquance égale au signal noir..
J'aimerai savoir comment detecter quand le signal est proche de la valeur 0 (+- 5%) et ainsi declencher le burst automatiquement ?
Comment peut on créer un burst sinusoidal de la fréquence du courant noir ?
Comment obtenir l'envelope du signal final noir (=signal bleu) ?
Voila j'ai plein de question sans reponse et j'aimerai bien un peu d'aide. Merci par avance.
Guillaume VINCENT
IUT b GEii LYON FRANCE

Bonjour,
le module USB-6009 dispose d'un trigger numérique ou software. Vous ne pouvez donc pas utiliser une entrée analogique pour déclencher la génération d'un signal sur une voie spécifique.
Vous devrez donc déclencher les données uniquement par soft après traitement des données acquises (lorsque les valeurs de mesures dépassent une valeur seuil). Vous aurez compris que l'application ne sera probablement pas réactive à la milliseconde près. Qu'elle est l'échelle de fréquence de votre système?
Vous aurez à utiliser les fonctions de la palette "traitement du signal" ainsi que de la palette "mathématiques" pour effectuer des traitements sur vos signaux.
Cordialement,
Manuel R
AE dans une autre vie

Signal envelope changing...?

I'm trying to generate two sinuosoids (one right after the other) that are offset from a carrier. I know they are being generated and can be picked up and displayed by the RFSA. Everything up to that point appears fine. However the envelope of the signal is not constant even when I go above and below the carrier the same amount for the same power level, etc. So my question is if there's any way to fix this issue? Any insight is appreciated.
Thanks.
- Eric

Hello Eric,
The first thing I would check is to make sure that you are using the latest version of the NI-RFSA driver (NI-RFSA 2.0.1). There have been a few fixes implemented in this driver that impact how the attenuaters in the PXI-566x work. Which brings up the question, what exact hardware are you using?
It would be helpful if you could attach a screenshot of the behavior you are seeing, along with the specific settings used to configure the device. Is there a specific NI-RFSA shipping example that you are running to demonstrate this behavior? Let us know some more information about the behavior you are seeing and we can probably provide some suggestions.
Travis G.
Applications Engineering
National Instruments
www.ni.com/support

How to extract the signal out from the waveform by my designated power level?

Dear all,
How can I extract the signal from the waveform accroding to the power level? I read the Trigger&Gate.vi, but this vi extract signal according to the duration time. I want to extract signal according to power level.
As shown in the following figures, the signal I want to process is between 130000 to 140000, if I zoom in, I can see the the useful signal is between 135400 to 138200. The question is how to extract the signal in the zone?
I tried the sub_NoiseEst_And_Chop_Shell.vi in the Packet_based_link example too, but this subvi seemed to be a little slow. Can anybody give me better advice? Thanks in advance!
Solved!
Go to Solution.

I was working on something similar but haven't had time to fully develop it.
My idea was to use an envelope detector (low pass filter) and then use an energy detection VI on the envelope.
Here's where I left off
Anthony F.
Product Marketing Engineer
National Instruments
Attachments:
test.vi ‏331 KB

Envelope detection using hilbert transform labview

I'm performing signal envelope detector using Hilbert transform however having problems. I have searched and tried some ways on forum but it still not been. I have refer the following article for my project
I'm looking forward you see and correct errors happen.
Thanks so much.
Attachments:
Signal Envelope Detector.vi ‏127 KB
sData.zip ‏903 KB
Shulkin_-_HF_Acceleration_in_Enveloping_in_Labview_2.pdf ‏434 KB

Thanks for your answer.
Make your idea is quite similar to the way I have done. After thoroughly study I have a better understanding of the Hilbert transform and taking the signal envelope.
This is a project completed repair. However, the envelope does not seem to be beautiful.
Hope everyone has comments for issues in order to I can handle more perfect for your project.
Again thanks for comments.
Attachments:
Signal Envelope Detector.vi ‏127 KB
sEMG_1.zip ‏903 KB

Envelope of burst of sine waveform

Hi,
I want to get only the envelope of the burst of sine wave as attached in the picture.
Is there any standard functions available to find the envelope.Please tell me how to find the envelope of a signal.
Attachments:
signalburst.PNG ‏20 KB

I have tried to find the envelope of the signal using Hilbert transform but i didnt get smooth waveform.
I have attached the vi which i tried..Please tell me what is the problem..How can i get smooth waveform
Attachments:
Envelope.vi ‏30 KB

Airtunes - picking up radio signals

Using an iMac G5, with iTunes 9.03, Airport Express with v6.3 firmware.
When I stream audio to my stereo I get radio signals coming through in the background. Very annoying at lower volume. Only way to get rid of it is to raise the volume quite loud. I thought at first it was just the extremely old receiver I have, then I tried it with a more modern system and got the same results.
When I stop playing music in iTunes, the sound still comes through the stereo for a brief bit before stopping (10 seconds or so) - I assume because when nothing is playing streaming is paused.
Any clues on how to block out the unwanted frequencies? Internet robustness is on, and I couldn't find any settings anywhere in the airport admin utility that might help.
I'm very close to enveloping the airport express in copper shielding
Any ideas would be greatly appreciated.

Reminds me of my grad school days in Rochester, NY, when vinyl was the source of all music. I had a decent stereo system for an impoverished student, but imagine my surprise when I learned, and not gently, that the phono cartridge in my turntable was perfectly attuned to receive the radio frequency used by the Rochester public transit bus dispatcher, whose signal was very strong indeed. I might be grooving along to Jefferson Starship, the Grateful Dead or Pink Floyd, gently ratlling the windows throughout our apartment and adjoining houses, puffing on a little of this or a little of that, when without warning I would be jolted out of my chair and across the room by an ear-shattering interjection of static-laden and distorted verbiage about the University Avenue local D bus, whose driver had just been vomited on my a drunk and needed advice about how to handle it. It was a real mood-spoiler for me. I replaced my phonograph cartridge and the problem was solved

MWI envelope indicator will not come on CCM 4.1(3)sr1

I have a Callmanager 4.1(3)sr1 installation with a Unity 4.0(5) and we are experiencing a weird problem on one extension only. Other extensions are not affected. I have a shared Extension on the second line of numerous 7940/60. This extension is set to forward all to VM. When people leaves a vm for this extension, I can see Unity using one of the VM port to have CCM light the MWI envelope indicator. I get no such MWI indicator, the flashing envelope on the phone. MWI works for all other extensions and I see the MWI request on the VM ports in Unity for the extension in question.
Seeing this, I focused on the CCM side and dialed the MWI on and off extension from the Extension that is having the problem. I dial the MWI on number and it immediately hangs up and there no MWI idicator. I try it with other extensions with the exact same Partition and CSS and they work perfectly.
I cannot seem to get the MWI light on for one particular extension. Anybody have any thoughts or ideas? I definitely see that it is not a CSS or Partition issue as it is the same as any other extension. I do not get a busy signal or error messages when I dial the mwi on number. This is most likely the reason why MWI for this extension is not work.

Thanks for the reply. I did play change the MWI policy on the line to different settings and tried again after resetting the phones. This proved unsucessful in trying to fix the problem. Two IP communicator was also created/added to have the same shared line on line two. One of the IP communicator also had a third line just in case. All CSS and Partition was set to the exact mirror. The problem still persist. The ip commicator can turn off/on MWI on all lines except for the problem extension.

Hi help abt BPSK/QPSK signal waveform

Hi sir,
I am using modulation toolkit for generating bpsk/qpsk signals.Here i am attaching wavefrom image.what i seen the psk waveform like this(psk1.jpg and psk2.jpg).
But i am getting like this(bpsk_ouput.jpg).is it correct?it looks like only phase changes are appearing.
Please give me some clear information abt this signals.
Thanking you sir
Attachments:
psk2.JPG ‏107 KB
bpsk_ouput.JPG ‏150 KB
psk1.JPG ‏71 KB

hello， David L.,
I am also trying to use 5640R to get a PSK modulation signal. But the result is not correct. The envelope should be constant in PSK modulation signal. what I get is shown in pic1.
My Host and FPGA .Vi is posted in pic 2 and pic3.
can you help me to resolve it?
Niton
Attachments:
pic1.jpg ‏17 KB
PIC2_host.JPG ‏17 KB
pic3_FPGA.JPG ‏90 KB

Calculate envelope curve x spacing

Hi,
I have a sinusoidal voltage signal where the amplitude changes with time. I want to determine the amplitude's dependence on another variable, so I need to separate out the oscillatory information. I tried using the calculate envelope curve function, but the x channel spacing is not equidistant - you can't combine the x and y channels to make a waveform channel - so I don't know how to compare these channels with my other data (i.e. using regression).
It seems that the envelope function goes through the data set and selects out all of the extreme points, divides these between upper and lower bounds, and puts these data points in the new channels. Is there some function that would allow me to set up an x channel with equally spaced points, and interpolate the corresponding values for the envelope?
I tried using a curve fit to approximate the amplitude data, but it doesn't retain enough of the features.
Thanks, Myra
Solved!
Go to Solution.

Hi Myra,
It sounds like the key issue you're facing is that you have one curve with non-equadistant X values and a second curve with equadistant values, and you want to compare the Y values of those 2 curves at exactly the same X values. This is what the "Linear Mapping" function in the ANALYSIS Curve Fitting palette does. Just provide the X and Y channels of the non-equadistant curve in the first two dialog fields and the X channel of the equadistant curve in the third field. This will create a linearly interpolated version of your non-equadistant curve that has exactly the (equadistant) X values as your other curve.
If your equadistant X value curve is a waveform, then you'll need to first use the "Numeric Channels <=> Waveform Channels" function from the ANALYSIS Channel Functions palette, in oder to create that X channel you'll need in the third dialog field as described above.
Ask if you have further questions,
Brad Turpin
DIAdem Product Support Engineer
National Instruments

No video signal using mini dvi to vga adapter.

I just bought a macmini,the last generation. Separately I bought on the apple store a mini dvi to vga adapter because when I bought the macmini I forgot to buy that....once the adapter arrived I tried to turno on the mini,everything seems to be normal,the mini works,the audio signal is normal and after the startup it asks me to choose the language,but the screen says there's no INPUT SIGNAL. I tried another mini dvi to vga adapter,the vga wire works with my pc so I didn't try another one,I tried the reset of the mini,nothing....do I have to try with "miniport to vga" adapter or is there something else I can try?

I got my Mac Mini yesterday and I am having the exact same problem as you are having.
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Battery , time , signal strength bar is not getting displayed in home screen , these will be displayed only when i click on any app. Can u let me know the setting change ?

Battery , time , signal strength bar is not getting displayed in home screen , these will be displayed only when i click on any app. Can u let me know the setting change ?

Did you check the Zoom setting?
Have you tried a reset (reboot)? Hold HOME and SLEEP until an Apple logo appears.
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No signal via DVI to VGA adapter on my video projector Sharp PGM 15X

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I have a big problem with my video projector. It´s connected via mini DVI to VGA adapter to
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To resize the solution on both, or one of them doesn´t help.
When I use my Bootcamp and reboot with Windows XP there is a picture on the video projector.
I cant believe this.
What should I do to fix this problem?

I got my Mac Mini yesterday and I am having the exact same problem as you are having.
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Mini Displayport to vga adapter on MacBook pro 13" late 2011. No signal on external monitor

Hi
Connecting a Late 2011 MacBook Pro 13" to an external monitor, trough mini Dispalyport to vga adapter, i see "no signal" messagge on external monitor, even if i get it as secondary monitor on Preferences > Monitor of my MacBook it's visible (i can change resolution, position, clone screen, ecc.).
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Hi
i did what you said and tried with other resolution/refresh rate combinations, also with anoter external monitor (and vga cable) but its still the same: monitor is detected but there's no signal.
Now I will try to chek if the adapter works on other pc and monitor.
Thanks
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Envelope Of Signal

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