What is the period in an waveform generated by Periodic Random Noise Waveform VI?

[uwkram]

I am running LabVIEW 8.5.

I am generating a periodic random noise wavefrom from the Periodic Random Noise Waveform VI. inside a while loop.  The loop is timed to match the buffer.  My question is:  does this VI generate a periodic waveform that spans the length of the waveform?  Seeding is default and reset is no.

My goal is to create a periodic random waveform from the VI that repeats itself every in every execution of the while loop.  Something that looks like the example below.  (Regen is turned off)  Should I place the vi is outside the while loop?

[RavensFan]

Did you look into the help file for that VI?  It tells you all you need to know.

1.  reset signal, if TRUE, resets the seed to the seed control value and the time stamp to zero. The default is FALSE.

2.  seed, when greater than 0, causes reseeding of the noise sample generator. The default is –1. LabVIEW maintains the internal seed state independently for each instance of this reentrant VI. For a specific instance of this VI, if seed is less than or equal to 0, LabVIEW does not reseed the noise generator, and the noise generator resumes producing noise samples as a continuation of the previous noise sequence.

And of course if you put the the Noise generator outside the loop, whatever it creates gets put at the tunnel, and the Analog Write will keep reusing that waveform on every loop iteration.

So I'd either put the waveform generator outside the loop, or wire up the reest with True and a see value of 1 or higher.

[uwkram]

Thanks for the reply.

I've read the help file, but what isn't clear is if the single record generated is supposed to be periodic by itself.

This is what I think it's saying, and please correct me if I'm wrong:

1.  reset signal-if true, then when the vi is placed in a while loop it would generate a distinct record very loop

2.  seed-when less than zero, it generates a continuous signal when placed in a while loop.  However, it is not clear that the signal would be periodic.

I am concerned about the periodic nature of the signal generated by the vi, specifically the continuity between the beginning of the record and the end of the record if I were to repeat 1 record in a while loop by placing the vi outside the while loop.

[RavensFan]

Well the help file said that this about the signal generatedL

"The output array contains all frequencies which can be represented with an integral number of cycles in the requested number of samples. Each frequency-domain component has a magnitude of the input spectral amplitude and random phase."

So that sounds to me like it would be continuous if you repeated it in a loop.

I would set the reset to be True, and use a seed number of 1 and try that.  (Hey wait, I did say that in my previous post!

Why don't you put together a VI that lets you try out different options.  Have a For Loop that runs twice and compare the waveform output from the first iteration with the second.