How can I compare a signal.

[LKCH9]

Hi:

I am acquiring a signal from a scope, that signal must have a frequency of KHz, and a amplitude between 4.8 and 5.2 volts.

How can with lab view verify that the signal have the correct parameters??

[Dennis_Knutson]

First, see if the scope supports these measurments internally. You have not mentioned the make and model but most modern scopes have a whole series of built-in measurment functions. Second, if you want to do it in LabVIEW, there are the functions on the Signal Processing>Waveform Measurements palette. Extract Single Tone Information returns frequency and amplitude. There are even (shudder), Express VIs for these measurements. You need to have the full version of LabVIEW for any of these functions.

[LKCH9]

yes mi scope works for this...

And i use the single tone, the amplitude that give the vi its correct, but the frecuency give .000112.

Do you have idea why?

Also i try to use the multiple tone information but i dont know what kind of indicator i have to put to read my measurements... 

[Dennis_Knutson]

My guess it that all that you did was wire up a array of DBL/SGL to the input. This function requires you to use the waveform data type. The waveform data type includes a dt value. This is necessary for the frequency to be correctly calculated. Otherwise, it will assume a sample rate of 1. You can easily convert a DBL/SGL array to a waveform data type with the Build Waveform function. You can get the sample rate from the scope or from you code where you set it.

For the Extract  Multiple Tone, just right click on the output and select 'Create Indicator'. That works for any LabVIEW function by the way and you can right click on any function input and select 'Create Control'.

[LKCH9]

Thx dennis, i just add the Build Waveform function, but doestn work, can you take a look?

[LKCH9]

Dennis thx, finally i can take my data and it is corret

REGARDS!!

[Dennis_Knutson]

Right click on the Build Waveform and select Add Element or just drag it down until yu have two. You want to keep the Y array and make the other element dt, as I said. This is just like the Unbundle by Name so you select a different element by right clicking on the element and doing a Select Item. Wire the x increment from the Agilent Read Waveform function to the dt input.