numeric integration

[heang]

hello
someone pls help
i have been obtaining the correct value of area under the curve using 'numeric integration' vi
for my signal sampling frequency setting to 1000 Hz

but it does not correct for setting to 10000Hz
i doubt what is the dt it means in the numeric integration. does it mean the time interval between 2 samples?
or the dt between the region that encloses the area to be integrated/?
is there anyway to trace the code written in  which is already written in dll form such this numeric integration?
thanks

[altenbach]

dt is the sampling step size. Since the samples are assumed to be spaced equally, it is the time difference between adjacent points.

Things like that are very easy to find out. SImply right-click on the function and select "help". 🙂

(Sorry, I don't understand your trace/dll question.)

[heang]

hello
i doubt what is about the sampling step size
as i have the sampling frequency 1000hz
the sampling step should be 0.001s

the sampling frequency 10000hz
then the sampling step should be 0.0001 s
i try to use this numeric integration vi, but the result is not the same for this 2 sampling frequency.

initially i define the dt is the time interval which encloses the area to be integrated. i may have wrong definition.but i get the accurate result for 1000Hz
when it i set to 10000hz, the result getting weird.
any comment to rectify the usage of this vi ?

regards

[altenbach]

Please attach a simplified version of your VI containing typical data as diagram constants for both sampling rates.

[UCT]

Hi all,

Im new to labview and am not sure how to perform the correct integration of a signal. The problem i have is that after integration the signal is offset by a value. I know this is due to the antiderivative of the function is the sum of the antiderivative plus a constant C. I tried to remove this offset by measuring the dc value and subtracting it. The problem is that the resuslt is a scalar value and not a waveform. The integral of a sine signal should give me -cos +c signal and i just want to remove the constant c and obtain the -cos waveform. Which VIs should i be using?

[KateB]

try screenshot