Joint time frequency analysis in Signal Express?

Is it possible to do joint time frequency analysis in Signal Express? I didn't see it in the Analysis section, so I'm assuming it's a separate tool that has to be added, if even possible in Signal Express. Help?
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SignalExpress does not natively support joint time frequency analysis. However, check out the Sound and Vibration toolkit which expands upon SignalExpress. It may do what you want.
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Time Frequency Analysis

Is there any way to perform time-frequency analysis(spectrogram ) in DIAdem? Ideally, I got like to play the waveform in one section of the VIEWER and other section of the VIEWER would have the spectrogram of the data within the band cursor.
Does anyone think this is possible in DIAdem?

Hi Neuropotential,
What you're asking for is possible, but it's not an out of the box feature. We have a posted example application for doing joint time frequency analysis in REPORT at
http://zone.ni.com/devzone/cda/tut/p/id/3549
You could set the same sort of thing up in VIEW with the new 3D Contour Area available in VIEW in DIAdem 11.1. I'm curious how you'd like the interactive part to work in VIEW and also how large your data sets are.
Brad Turping
DIAdem Product Support Engineer
National Instruments

How can I get the time for a simulate signal express vi waveform?

I tried converting to an array and then indexing, but every index I try only gives me the y value. See attached VI for clarification on what I mean.
Attachments:
simulate signal.vi ‏49 KB

You will have to keep track of that yourself. You are sampling at 360kHz. This means that each sample is ~2.8us. You can easily get the time by taking that dt (2.8us) multiplied by the sample index and adding the time at which the first sample was taken.
There are only two ways to tell somebody thanks: Kudos and Marked Solutions
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Frequency analysis of time varying data

I want to add a routine for frequency analysis of before and after strong impulse on a body.
Some vibration sensors will be attached to the body.
In this case, I was told I need to use a time-varying method like wavelet or any other to analysis instead of simple FFT.
I installed wavelet package but I have no idea how to use it.
(Wavelet method seems to be popular in reduction of noise.)
Only what I want to know is the frequency elements in dynamics.
Can you recommend any tools (functions) for my purpose?
Are there some LabVIEW examples?
I am using LV2009 and some extra toolkits (developer suites).
labmaster.

labmaster wrote:
I want to ask some curious things.
1. I have to analysis the spectrum of frequency in dynamic signal.
In case of presenting dB, how to know the frequencies?
2. In high sampling rate (1MHz), the low frequency element can't be analyzed. (too small window for 60Hz in my last example).
If so, generally, do I have to down sampling to ~1kHz for the 1MHz in wavelet or short time FT?
Take a look on how the Express VI you are using are made. The Express VI you are using is located here
C:\Program files\National Instruments\LabVIEW 2010\vi.lib\addons\Time Frequency Analysis\_express\_TimeFrequencySpectrogramConfig.llb
The VI you need to open is the configure.vi. Copy this VI to your user.lib folder before doing any work on it.
To answer your first question. The dB setting will change the Y axis scaling, and not the X axis scaling. Which is the frequncy axis
The step between each frequncy bin will be( number of Frequency bins/(Fsample/2)). So using 1 MHz may reduce resolution. Perhaps 10 KHz will be bettter for you to use.
Besides which, my opinion is that Express VIs Carthage must be destroyed deleted
(Sorry no Labview "brag list" so far)

Signal Express Large TDMS File Recording Error

Hello,
I have the following application and I am looking for some tips on the best way to approach the problem with Signal Express:
I am attempting to using Signal Express 2009 (Sound and Vibration Assistant) to collect random vibration data on three channels over an extended period of time -- about 20 hours total. My sample rate is 2kHz. Sampling at that rate over that period of time invovles the creation of a very large TDMS file, which is intended for various types of analysis in signal express later or some other application later on. One of the analysis functions to be done is a PSD (Power Spectral Density) plot to determine the vibration levels distributed over a band of frequencies during the log.
My original solution was to collect a single large TDMS file. I did this with Signal Express recording options configured to save and restart "in current log" after 1 hour worth of data is collected. I configured it this way because if there is a crash/sudden loss of power during data collection, I wanted to ensure that only up to an hours worth of data would be lost. I tested this option and the integrity of the file after a crash by killing the SignalExpress process in the middle of recording the large TDMS file (after a few save log file conditions had been met). Unfortunately, when I restart signal express and try to load the log file data in playback mode an error indicating "TDMS Data Corrupt" (or similiar) is displayed. My TDMS file is large, so it obviously contains some data; however, Signal Express does not index its time and I can not view the data within the file. The .tdms_index file is also present but the meta data.txt file is not generated. Is there any way to insure that I will have at least partially valid data that can be processed from a single TDMS file in the event of a crash during mid-logging? I don't have too much experience dealing with random vibration data, so are there any tips for generating vibration level PSD curves for large files over such a long time length?
My solution to this problem thusfar has been to log the data to seperate .TDMS files, about an hour in length each. This should result in about 20 files in my final application. Since I want to take a PSD, which ends up being a statistical average over the whole time period. I plan on generating a curve for each of these files and averaging all 20 of them together to get the overall vibration PSD curve for the 20 hour time period.

JMat,
Based on the description of your application, I would recommend writing the data to a "new log" every hour (or more often). Based on some of my testing, if you use "current log" and S&V Assistant crashes, the entire TDMS file will be corrupted. This seems consistent with what you're seeing.
It would be good if you could clarify why you're hoping to use "current log" instead of "new log". I'll assume an answer so I can provide a few more details in this response. I assume it's because you want to be able to perform the PSD over the entire logged file (all 20 hours). And the easiest way to do that is if all 20 hours are recorded in a continuous file. If this is the case, then we can still help you accomplish the desired outcome, but also ensure that you don't lose data if the system crashes at some point during the monitoring.
If you use "new log" for your logging configuration, you'll end up having 20 TDMS files when the run is complete. If the system crashes, any files that are already done writing will not be corrupted (I tested this). All you need to do is concatenate the files to make a single one. If this would work for you, we can talk about various solutions we can provide to accomplish this task. Let me know.
Now there is one thing I want to bring to your attention about logging multiple files from SignalExpress, whether you use "current log' or "new log". The Windows OS is not deterministic. Meaning that it cannot guarantee how long it takes for an operation to complete. For your particular application, this basically means that between log files there will be some short gap in time that the data is not being saved to disk. Based on my testing, it looks like this time could be between 1-3 seconds. This time depends heavily on how many other applications Windows has running at the same time.
So when you concatenate the signals, you can choose to concatenate them "absolutely", meaning there will be a 1-3 second gap between the different waveforms recorded. Or you can concatenate them to assume there is no time gap between logs, resulting in a pseudo-continuous waveform (it looks continuous to you and the analysis routine).
If neither of these options are suitable, let me know.
Thanks, Jared

Frequency Analysis? How do I get frequency characteristics of a signal given in .wav format ?

I am new to Labview would really apprecite your time and help...
frequency Analysis? How do I get frequency characteristics of a signal given in .wav format ?
I have attached the signal I am trying to analyze.
Have nothing to offer in return but gratitude
Cheers !
Message Edited by Komal Khalid on 04-11-2010 10:59 PM

If you have labview 8.x or 9.x you can do this. Go to help in the toolbar. Select "Find Examples" and then search for sound. Locate the "Sound File to Sound Output.vi" This example will help in your task. Remember that Labview is shipped with a lot of useful examples. That can help you in your learning process
Good luck
Ps you can also read wav files, and find examples in Labview 7.x. But I do not know the name of the similar examples in 7.x
Edit: Please use zip files then you are not able to attach files. Do not link to sites outside. The site you linked to was very annoying. Could not download
Message Edited by Coq Rouge on 04-12-2010 02:38 PM
Besides which, my opinion is that Express VIs Carthage must be destroyed deleted
(Sorry no Labview "brag list" so far)

Why can I only import one TDMS signal at a time in Signal Express?

I have dozens of data files which were originally recorded as LabVIEW waveform files. I converted them all to TDMS in LabVIEW in hopes that I could import them to Signal Express (with the S&V Suite) for further processing. Each data file contains more than 20 channels.
When I try to import them to SE, I am unable to import the entire group. Instead, I am limited to one channel at a time. This would take days to import all channels, and is not what I want at all. Is there some way to import an entire group of channels at once?
JR

I was using the "Logged Signals from LabVIEW TDMS file" import; perhaps I had installed it on SE 2.5 before upgrading to 3.0. Regardless, I downloaded the ZIP file, and ran the msi with the "Repair" function. This did not change the functionality. I then used your suggestion, and redigitized one of the files with the Express VI set for TDMS. Same deal, although instead of the channel names I had been able to specify using the TDMS subVIs, now it lists them all as "Voltage_x", where x is a channel number beginning with 0.
I've attached two images as examples of what I'm experiencing. The first (temp1.JPG) shows where I've tried to select the entire group. You can see that "Convert File" is not enabled, and the sample information has not been read. The second image (temp2.JPG) shows where I've selected a channel. I am only able to select one channel, not a range. The "Convert File" button is now enabled, and sample information is correctly displayed.
Attachments:
temp1.JPG ‏57 KB
temp2.JPG ‏57 KB

I am using a DAQ board to get the singnal now i need to perform frequency analysis and this system doesn't employ any filters etc it's just a signal

Iam using AT-MIO-16E-2 board to retrieve the signal now i need to perfrom a frequency analysis and this process doesn't employ any filters etc.

There are a lot of shipping examples that you can look at. They're under Analyzing and Processing Signals>Signal Processing. There are software filters and window functions that you can use but if you are having aliasing problems, then the only thing you can do is add hardware filtering.

Time averaging problem - signal express

Can somebody help me with this problem? I am trying to perform time averaging from signal in Signal Express but the input and the output signals are the same. Attached is the printscreen of the process. Can somebody tell me what I am doing wrong?
Attachments:
signal.JPG ‏51 KB

You should post to the SignalExpress board.

How do i stop the automatic load of signal express every time i plug in an USB device?

This is the most invasive thing I have experienced with NI products. The only choice you get is to select a trial offer or pay for a license you can't X out.

what happens if you right-click on the NI Device Monitor in the notification area and click "clear all device associations"?
SCXI- 1000 Chassis w/ 1346 adapter
PCI 6281 DAQ card
SCXI- 1520 Bridge Board w/ 1314 Terminal Block (x2)
SCXI- 1180 Feedthrough Panel w/ 1302 Block
Signal Express 2014.
Win7 Enterprise

Can I use Signal Express for multiple customers for only the one time $699?

How do I go about distributing Signal Expresss applications to multiple customers?

Hi Nutter,
Unlike LabVIEW, Signal Express doesn’t have any file distribution capabilities. If your application uses only basic features, you could install the free LE version of Signal Express on as many computers as necessary. If you need the full capabilities of Signal Express, however, you would need to purchase a license for each customer.
An alternative to paying for Signal Express for each customer deployment would be to generate LabVIEW code from the Signal Express project and create an executable. This process is described in the Knowledge Base articles Generate LabVIEW VIs from Signal Express and Deploying VIs generated in Signal Express. Note that this method requires that you have LabVIEW installed on your development computer with Application Builder capabilities.
Regards,
Message Edited by Luke G on 05-02-2007 12:23 PM
Luke
Applications Engineer
National Instruments

Poor network speed with 1st generation time capsule and multiple airport express 5Ghz. My network speed slows to a crawl when not close to the time capsule. I get the range that I need, but the speed is painfully slow.

Hello,
I have a first generation time capsule running 802.11n (b/g compatable) and the airport expresse's are the newer 5ghz models. I have 3 airport express's and I have the range that I need. I can run the time capsule using 802.11n 5ghz, but I loose the range and can't connect to all of the airport express's. My computers and mobile devices run 802.11n. Does anyone have any suggestions on how to increase the network speed. Would the new airport extreme fix the problem?
Thank you

Unfortunately, you are experiencing one of the downsides to 5 GHz. That's because the higher frequency 5 GHz signals are much weaker than 2.4 GHz signals.
After all, you always have to give up something to gain something else. In the case of 5 GHz, you gain potential speed but in return, you must give up penetration power and distance capability.
In order to work well, 5 GHz signals need to almost have a line-of-sight relationship between devices. Unless you can achieve this, you will do much better to leave the Time Capsule running at the 802.11n (b/g compatible) 2.4 GHz Radio Mode and allow the Express devices to "extend" that network.
As for the location of the AirPort Express devices in an exended network, that is critical for best performance. That's because the Express can only "extend" the quality and bandwidth of the signal that it receives. Post back if you need a few more tips on how to find the best location for the AirPort Express devices.
Would the new airport extreme fix the problem?
Unfortunately, no.

How can i generate AMI line codes in LabView signal express?

i wish to conduct a project that uses AMI line codes. but i have a hard time using signal express to generate it. can anyone help me with that?

Hello Barry,
That is really a problem, in LabVIEW, we can only convert vi to the previous version, I have version 7.1 and so I can only convert to version 7.0 and you cannot open this too.
But I think that it's very easy to do what I'm trying to explain you.
Go to the cluster group in the functions pallete. Place an unbundle by name function in the diagram and connect it to the data that's comming out of the FFT Power spectrum vi - the pink (or watever) wire.
Click in the white part of it (it should contain something like f0), choose magnitude.
This is now an array that you can connect to the peak detector function.
Take care about the threshold and width parameters of the peak detector.
Take a look at your signal and decide the amplitude and width of the peaks you want to detect. The threshold is the amplitude above what you consider as a peak, the width is a little bit more complicated - to begin, 3 or 4 should be a good number if you signal is not too noisy - bigger widths will somehow do a kind of a low pass filtering to your signal.
The position output of your peak detector is an array of locations where your peaks were found.
Keep in mind you are now working in frequency domain and that position means something in the frequency domain.
The array you placed as input of the peak detector is an array of points starting in f0 and separated by df (the other elements of the cluster).
So to calculate the real value of the peaks, you have to multiply them by df and add them f0.
Sorry by the big text and sorry if I went too much in detail,
Hope it helps,
Paulo

First generation time capsule and older air express with Lion

I think the change/update to Netatalk has left many of Apples own devices stranded on Lion. I had to eliminate my backup to time capsule and move it to a local firewire drive. Printing has also slowed to a crawl.. no more hit print and get from printer; now it is several minutes.
What have your experiences been on these older Apple devices. Has anyone found a way to update or heard if Apple plan to make updates available. I assume the go to market of Lion did not allow time for regression testing on an array of Apple devicea.
I guess one fix is to get rid of and purchase all new devices. that is not very green let alone consumer friendly...
Any solutions welcome!

Unfortunately, you are experiencing one of the downsides to 5 GHz. That's because the higher frequency 5 GHz signals are much weaker than 2.4 GHz signals.
After all, you always have to give up something to gain something else. In the case of 5 GHz, you gain potential speed but in return, you must give up penetration power and distance capability.
In order to work well, 5 GHz signals need to almost have a line-of-sight relationship between devices. Unless you can achieve this, you will do much better to leave the Time Capsule running at the 802.11n (b/g compatible) 2.4 GHz Radio Mode and allow the Express devices to "extend" that network.
As for the location of the AirPort Express devices in an exended network, that is critical for best performance. That's because the Express can only "extend" the quality and bandwidth of the signal that it receives. Post back if you need a few more tips on how to find the best location for the AirPort Express devices.
Would the new airport extreme fix the problem?
Unfortunately, no.

Simulate Signal Express VI is sending two periods of the wave per loop iteration - how can I reduce this to one period?

Hello,
I've been trying to use the Signal Generator Express VI and DAQ Assistant in order to generate an output waveform, as seen in this NI tutorial video:
http://www.ni.com/academic/students/learn-daq/generate/ (timestamp is at 2:07 for what I'm trying to do)
For background, I'm trying to move a piston device using Labview. The sine waveform is intended to move the piston at a smooth speed. For every loop iteration, the Simulate Signal VI running into my DAQ Assistant moves the piston to its maximum displacement and back twice. I cannot determine why this is occuring.
The settings in my "Configure Simulate Signal" tab are as follows:
Frequency: 1Hz
Phase: 90 deg
Amplitude: 2
Offset: -2
I would like my piston to only reach its maximum displacement and return for every iteration of the loop. I've tried adjusting all of the settings within "Configure Simluate Signal" but I can only work in even numbers - sending the piston back and fourth two, four, or eight times, ect.

The Simulate Signal VI is set for integer number of cycles and the default frequency set in the Cycles per Second control is 3.75 Hz. That results in the signal containing three complete cycles and the data array contains 8000 elements, not the nominla 10000 specified in the Express VI dialog.
If you only want one cycle, you need to specify the signal so that you only get one. Either reduce the frequency or reduce the number of samples.
As you have noticed Express VIs do one thing exceedingly well: They obscure what is going on inside. I pulled your signal generation code out into a separate VI and then created a generator which will generate the same signal but allow you to select the number of cycles. It uses the Sine Waveform.vi from the Signal Processing >> Waveform Generation palette.
I also recommend that you change the structure of your program. The use of sequence structures is discouraged in LabVIEW because they defeat dataflow are very inflexible when changes need to be made. A Producer/Consumer Design Pattern plus a state machine would probably be a good choice. This will allow separation of the daq acquisition from the saving to file so that the timing of one does not constrain the timing of the other.
Setting the Analog Input Read to read multiple samples simultaneously and using the hardware timing of the data acquisiton device will get data faster and the timing will be precisely (compared to software timing) controlled by the hardware.
Writing to the same file in parallel loops probably results in some strange behavior such as differing numbers of writes from acquired data compared to generated cycles. As the file grows, the writes may slow down due to the OS needing to fragment or reallocate space for the file.
Lynn
Attachments:
Signal generator.vi ‏49 KB

Joint time frequency analysis in Signal Express?

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