Play waveform of a pressure signal

Hello everybody,
I'm trying to play the next waveform using the sound Labview Tools but i can not or i don't obtain representative results.
I also tried to do a multiplication with a sine waveform to have an audible waveform but i couldn't.
Somebody could help me to play this waveform (here i attached the pressure i obtained):
Attachments:
Waveform.JPG ‏36 KB

Please post this question to the LabVIEW forum and not to the Motion Control and Motor Drives forum. Posting to the LabVIEW forum for this type of questions will increase your chances of getting a good answer significantly.
You also should be a bit more specific about what you really want to accomplish. Posting some LabVIEW code is also a good idea.
Thanks and best regads,
Jochen Klier
National Instruments

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hello,
what i have is a waveform graph and i would like to play the waveform using the play waveform express vi. my problem is the data type i am wiring into the express vi is not compatiable. i understand the error, i just am not sure how to make it compatiable.
you may ask why i don't just use the correct waveform graph. the answer is that this waveform graph i have now is the result of filtering, fft, and ifft calculations and would like to get this graph to work and not change my previous work.
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Attachments:
playWave.vi ‏289 KB

Hi,
I think what you need to do is use the Build Waveform VI on the waveform palette. This 'bundles' the dt and Y array of values into the waveform data type which the graph and Express VI(s) will accept.
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Attachments:
playWave.vi ‏292 KB

Play Waveform Express VI

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Attachments:
Filter Exercise.vi ‏87 KB

You can convert the Express VI to a regular VI by right clicking and selecting Open Front Panel. It can then be modified. You can also provide the sampling frequency to the filter function you originally had.
Message Edited by Dennis Knutson on 03-12-2007 01:17 PM
Attachments:
Get Sample Frequency.jpg ‏19 KB

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Attachments:
scaling.vi ‏69 KB

JaymeW wrote:
Hi kirkbardini,
According to this article about Low Volume From Sound VI, you can use a scalar multiple to increase the volume of a sound saved to a .wav file, so you should be able to do this before playing it. Does that not work for you?
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Besides which, my opinion is that Express VIs Carthage must be destroyed deleted
(Sorry no Labview "brag list" so far)

Play waveform output level

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Sound File Read and Express Play WaveForm.

Hi, all
I am trying to control the volume on the Play WaveForm express vi, but have not been able to make this happen. Does any one have suggestions that I can run with.
Thank you.

I have found two examples of an Audio Equalizer that controls a sound output. The first is simplified version of the second. I hope this helps!
Audio Equalizer (simplified): https://decibel.ni.com/content/docs/DOC-8435
Audio Equalizer (advanced): https://decibel.ni.com/content/docs/DOC-16037
Regards,
Jason D
Applications Engineer
National Instruments

Sound pressure signal as input

I want to use a function SV Time-Varying Loudness in the Sound and vibration suite. The output of this function is exactly what I require for my speech analysis.
I have a speech sample recorded from the microphone obviously a voltage signal. This function requires a sound pressure signal.
The voltage signal would be proportional to the sound pressure signal right? How do I convert this voltage signal to the sound pressure signal (Pa).
I'm not even sure if I can use this function. I trying to extract the features from the speech signal. The algorithms used for this are linear predictive coding , perceptual linear predictive coding and mel frequency cepstral coefficients.
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Your microphone should have calibration tables to relate the output voltage to an audio quantity like dB or perhaps even Pa.
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Hi,
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Hello SGC,
As far as I know, there is no artificial limit on the device number within LabVIEW.
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Attachments:
play waveform config window.png ‏13 KB

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Hi all,
I am currently doing a heart sound analyzer project. I acquired signal using NI USB 6008 continuosly. My program is able to saved the acquired signal into a wave file. But when I browse open the saved file, the output waveform did not look the same as the acquired input signal and also the sound of the heartbeat captured cannot be heard from the loud speaker though I have saved the file as a wav file. I am not sure if the method i use to save the acquired data as a wav file is correct. I have attach the print screen of the differences of the output I have notice and the program I have created. I would be glad if anyone here is able to troubleshoot my program.
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heart sound analyzer.zip ‏257 KB

Hi Brett Burger,
Thanks for your reply. For your information, I have set the sampling rate as 10000 as for the sound format, I have set the bits per sample as 16 bit, the rate as 11025 and the sound quality as mono. I tried using your method by changing the sampling rate as 8K but still my program encounter the same problem.
I wish to also create a button that is able to generate a preformatted report that contains VI documentation, data the VI returns, and report properties, such as the author, company, and number of pages only when I click on the button. I have created this in my program, but I am not sure why is it not working. Can you help troubleshoot my program. Or do you have any samples to provide me. Hope to hear from you soon.
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Attachments:
Heart Sounds1.vi ‏971 KB

How to view signal in a waveform chart in Labview Signal Express?

Hi,
I would like to view a signal in Signal Express 3.0 in a "waveform chart" but don't know how to do it and I am thinking that it may be impossible?
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Solved!
Go to Solution.

Hi Enrique,
You are correct that there is currently no waveform chart in SignalExpress. The closest thing you can get to, is recording the data as a log and then viewing it while recording (which I realize is not quite the same, interactive behavior).
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Why am I not seeing the LED blink faster on hardware when the waveform graph shows the signal updating?

I am using the cDAQ-9188 chassis with a NI 9476 in the 8th slot, and when I run my VI, the waveform gets updated if I change the frequency of a signal while the program is running, but the DO from the write does not get updated. I thought that write takes in the data from the digital waveform input, so I'm confused as to why the digital waveform indicator is updated with a new signal, but my LED into a DI module (9421) is not updating.
Thanks in advance for any tips and suggestions!
Speed2.vi calls Generate_PWM.vi, so Generate_PWM is a subVI inside Speed2.
Attachments:
Generate PWM.vi ‏34 KB
Speed2.vi ‏46 KB

Hi Ruthnan,
Sorry for the delay in response but after looking over that hardware it seems there should be enough counters in the chassis to support what you are doing. I believe you are getting the resource is reserved error because you have started one output task on that module thus reserving the reference. Once that task starts any additional task with get an error. It should be possible to use more than one counter in your application but it sounds like an error in the VI configuration. I am happy to help here to get an example up and running but I think it would be faster to open a service request for this issue. Let me know what you would like to do.
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Play waveform on speakers on mac OS X

Hi all,
I am new to Labview, so this question might be much simpler than I thought it was, but it has been driving me crazy the past few days.
Basically, I work in a university research lab. For the purposes of one of our projects, I need to generate waveforms, and output them through the speakers of my computer.
I can do that fine on a PC running Windows XP, however the lab I work in mostly uses Macs under OS X. The problem is I can't figure out how to get the Mac to play the waveform I generate using Labview on its speakers (I use the same VI on Windows and Mac OS to generate the waveform).
Which leads to my questions:
1) What sort of "vi sequence" am I supposed to use to get a Mac under OS X to play a waveform on its speakers?
2) If I can't play a waveform on a Mac, what sort of output should I make my "waveform generator" have?
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Thank you,
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John,
I have no trouble making my Mac make sounds. Dual G5, Mac OS X 10.4.11, LV 8.5 (but I have done it with many earlier versions as well).
I generate a sine array with the frequency and duration I want. I scale that to match the input to the Snd Write Waveform.vi. For the 16 bit inputs the scale is -32768 to + 32767. Set the sound format input to sound quality = mono, rate = 44100, bits per sample = 16 bit. Run.
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Help creating custom waveform to load into Signal Express

I've never had to create a custom wave form before so Im completely new to this process.
Basically I need two output channels. Both channels will have the same waveform structure but one will have a time offset. In other words one will be starting while the other is ending.
Channel 1 waveform would look like this: One sinewave cycle (.25hz) then zero output for one cycle. Repeat.
Channel 2 waveform (meanwhile) would look like this: zero output for one cycle (exactly the duration channel 1 is in its sinewave), then one sinewave cycle (.25hz).
Both repeat continuously but out of phase of eachother. This will be a force/deflection test involving two hydraulic actuators applying a load to two points on the same specimen. Basically creating a walking condition where the customer would apply force to one spot then with the other foot transfer body weight to the second spot.
this is more complicated than what the basic function generator can handle but I have heard of people creating their own waveform in Excel and loading that.
Would this be possible for my application? What would the column structure in excel look like?
I've never created or exported a waveform to excel.
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Hello OKors,
What if you were to use a Sequence step to separate the two waveforms (with "Run preceding steps before following steps" AND "Allow hardware reuse" checked) and had them output a finite amount of samples, such that each time one step executed a single cycle? It wouldn't be strictly timed as that would be handled in software rather than hardware, but it is a good place to start.
You could also import a signal that you created in Excel as an ASCII file and choose the delimiter (tab, comma) and start/end rows. It would probably have better timing qualities than using a Sequence step. To figure out what the signal would need to look like, I would recommend saving something to an ASCII file first to figure out what formatting SignalExpress would expect as an input.
Have a great weekend,

Play waveform of a pressure signal

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