How to get amplitude values of a continuous running signal?

[Parny]

Hi there,

I want to measure  the amplitude values of a random signal (like sine, square,triangular etc>>)?? Just trying to know how I can do that and also wish to store those amplitude values and compare them for some purpose to get the biggest value among them??

Thanking you.

[BillMe]

I think more information would be helpful. What version of LabVIEW are you using? How are you acquiring the signals? Are you post processing the stored data or wanting to compare while capturing?

Take a look at the Analog Waveform Measurements on the LabVIEW Programming or Signal Processing palette. For example, the Amplitude and Level VI might be something to consider assuming time domain measurements. With the File I/O VIs, storing the data should not be a problem. For finding the largest value, there is the Max/Min VI (under the Comparison palette). Just some things to look at.

[Parny]

Hi Bill,

Thanks for your time and reply. Here some more info,

The version is 8.5, also acquiring the signals from the production area. I want to post process the data within a span of time(probably short span). Infact I can measure the peak vale of the signal just by using some express VIs.

Overhead that I am looking here is, "to store those data in an array permanently" for the period of time I am going to monitor and then post process those data to get the max peak in the signal. Sure that I can't process the data live since its so dynamic where I may miss some of the data which is crucial. As u mentioned, tehre are many Max/Min VIs available, but only thing beating me up is  "to store those data in permanently". Again I can't store in a file or spreadsheet since its time critical, looking for something like array based or so to manipulate quickly??

Hope this may give more info needed!!

[craigc]

Hi Parny,

Im Confused here, Is it that you want to monitor the data in real time and then store the max and min values "Permanentlt" or are you acquiring a set of data and the analysing after to find the max and min?  Either way when you say permanently there is, as has been mentioned in your other thread, numerous ways to store this data.  Your question is a little ambiguos and it may just be a language barrier thing.  If you need to get the data process it and record a result in real time, you will have to store the max and min values into an array with the build array function and a shift register inside your acquisition loop.  so you append your max and min to an existing array if you prefer.  After you have stopped monitoring you then write the results to file.  If i have misunderstood your qeustion (Which i probably have) then you will have to explain a little further.

Regards

Craig

[GerdW]

Hi Parny,

why don't you stick to one thread?

Have you tried to use shift registers to hold your min/max values? This way you don't need to store the (big) measurement arrays but only 2 dbl values...

[PhillipBrooks]

To help others (and myself) understand; are you trying to create the equivelant of a "peak hold" like on a spectrum analyzer?

If so, then you would use a shift register as others have suggested.

[tbob]

Here is a vi that captures some data, stores into an array, and then processes the array to get the min, max, and average.

I hope this is what you want.

Message Edited by tbob on 09-28-2007 08:54 AM

[Parny]

I am able to do it now.

Big thanks to one and all.