CamilloN

Hello,i need a VI which makes the same as the matlab function "Polynomial curve fitting" (polyfit).Is this implemented in LabVIEW?kind regardsVincenzo NuzziUps,sorry i found it.

of course the word was filter :headbang: With the median and the butterworth filter my results aren't as good as the "running average" filter. What if i make a fast fourier transformation than overwrite the unwished frequencies with zeros and make than a inverse FFT? This could also be possible, or are there any problems. Now a question to all mathematician out there ;-) I know that the FFT mirrors the frequencies. What happens if i also overwrite the mirror-frequencies? Are they necessary for the inverse transformation?

Hello, i got a problem. I wanna know the dy/dx of a Signal. The signal is a array from a txt-file. To calculate the value isn't the Problem, but the Signal is not clean it has a few peaks from extern interferences. To calculate the value by hand i normally take two points on the x-axis and and look at the value of the y-axis...dy/dx and i got the result. If i make the width of the two points big, my result is not exact. If i make it to small the peak-influence is to big. How can i plane (is that the correct word for my intention???) the Signal WITHOUT moving the Signal to the left or to the right. Or is there another Method to calculate the dy/dx kind regards Vincenzo Nuzzi

Hallo, thanks you all for your help. I think the way you told is right, but i solved the Problem in a other way. I rectifi my signal so i have every time it starts a increasing data and i can use the treshold VI. So my signal looks like this. and i made it like this I think that was the easiest way. Thank you all.

Sorry for my bad english, it is a long time ago since the last time i used it. @ Neville This solution looks really difficult for me to solve. I have made pictures of my signal, perhaps you will understand my problem better. It shoul look like this. i measure the time between the two shown points but here i got a problem.

Hello there, I got a problem to find a x-point of a signal with de Vi "Treshold 1d Array". The signal i got is a normal Sin-wave. I read the signal from a spreadsheet. The signal starts with a zero-line with a little interferences, so it is not exactly zero And i need the x-point when the Signal is changed. Since now i used the Treshold VI an set the searching point to 0,2 for example. If the signal starts in the positiv half-wave i got no problem, but this chance is also 50:50 that it starts in the negative half-wave. When i start the measurement i don't know how it would look like. Is there a possibility to make a "not equal" with a hysteresis? A possible is that i take the signal the signal reverse it once and use the Treshold to both (reversed and normal) then i look which x-point is lower?? or??? Thanks for your help kind regards Vincenzo EDIT: My signal is looking like this

Thank you very much for your help, now i know how you got the time, it's clear. The Array Max&Min Vi is great, but i don't think i can take it. In the last days my signal is changed (since now i had only a forecast how it could look like). It is more like this Don't look at the numbers, i took the picture only as a example, it is also mirror-inverted. But like this it has no defined peaks. So i cannot search the min & max. But i know that the maxima of the Signal is 10V, can i search in the array for the point when the signal crosses this limit? And for the first signal i also don't search the min, because it could remain for a longer time 0 and i want, the Index when it begins to change. I think it must be possible with the Treshhold 1D Array, isn't it? Best regards Vincenzo Nuzzi

QUOTE No Problem, i got the development software. I got a few questions too ;-) You take the indices of the max-min function or also the array from the for-loop as your x-axis-variable, but is this the correct time? How does the PC know, how many milliseconds is between index 1 and index 2?

Thank you very much for your help. Sorry my real bad english it's been awhile since i used it last time. I have really no experience with LabView i have made nothing since now. I don't know which DAQ i use, i got here a "Datalogger" (a CPU and a RAM which stores signals.). With this they gave me premade VI's. I have not seen the signal yet so i can't give you accurate information about the interferences they got. I know that one is a normal sine (AC) which starts after a few seconds and the other is the response of a pressure pick-off (DC 0-10V). I think they are both not difficult as for example a Audiosignal or somthing like that. I only need the time between the two signals no absolut timestamp, but since now i havn't seen a timer like a stopwatch. My first idea was to find a VI which gives out a Timestamp when the signal passes a defined voltage and reaches a defined voltage. But i haven't found it yet. The time i have to measure will be between 0.5 and 2 milliseconds.

Hi, my problem is now a little bit more accurate than in my first Post. I got two Signals and i want to take the Time from the starting of the first till the second gets his peak. How can i convert these signals that i get (Data (64bit)) into a analog Signal? Is this necesary to measure? And how can i get a timestamp from the Point when the first Signal starts? (the Signal is normaly a little bit flickering between the Zero-Point but i want the timestamp when it really starts)

My real Problem is that i have two signals. The first is for example 5msec 0V and then it begins. The second is also 0V and begins a few msec later. Now i want to know which time is needed between the start of the first signal and the start of the second signal. And the start of the first signal and the max. of the second. By the Way how can i simulate the timeoffset from the first signal Thank you very much for your help

Ok i worked another while at this problem, and my solution doesn't work, so i tried your's orko. I put a Sinus Wave infront of the measure with 50Hz A normal durance of this is 20 msec, then the ascent must normally be 10msec. But your VI only gives me 5? I think it begins by zero, so i have only the half anscent. How can i change it? Is it possible to just put it into a While loop to give me more than one rating.

Thank you very much, but now i have the answer. it is a simple VI i think it's called Transition Measurements.vi in english.

Hello, i got a problem. I need the time from wich a signal started till it reaches the peak, and to store it in a Excel file. I think to store it isn't the problem. The signal is a very fast signal. It is the first time i use Labview, so i've got no experience with it. Thanks Vincenzo Nuzzi Sorry for my bad english