Generate random oscillating waves

[tastypotato]

Hello,

I'm stuck on something that may be pretty simple to do... I'm trying to get waves that look like this: http://www.scientificamerican.com/media/inline/000C600B-7F33-1C71-9EB7809EC588F2D7_arch1.gif to show up on a waveform graph.

The thing is I need to set an upper and lower limit and then have them go up and down randomly. I've looked in the simulate signal and I can't find anything that'll make it oscillate randomly between the two limits that I set.

Thank you for your time.

-Tom

[johnsold]

Tom,

First, neuro signals like that are not really random.  I have been writing LV code for a neuroscience research group studying theta waves for about 15 years.

I would generate a sine wave at the nominal frequency ( ~4-7 Hz  for theta for example) and then add some noise and possibly modulate the amplitude.

Lynn

[tastypotato]

Lynn,

I guess what I'm just trying to do is create a waveform that will look somewhat like a brain wave. Since the hardware that we are developing isn't working yet so I want to work on the Labview portion of the software. The most I am able to do with my current ability is to get some noise in and it just makes a mess. I'm trying to get Alpha, Delta, and Theta waves to look somewhat like they're supposed to - but I guess a regular sine wave will have to work for now. Thanks.

-Tom

[johnsold]

Tom,

For testing purposes I find it better to start with known signals anyway  I would start with sine waves.  When it works with those, then add noise.  When that works, try to find some brain wave signals to do further testing.

Good luck.

Lynn

[Steve.J]

I agree with Lynn - pure sine waves will give you a good indication of your code is working properly and not corrupting the signal in any way - it's much tougher to see problems with what is essentially random signals.  You can also insert slow square waves (like 0.1 Hz)  to see if your code correctly passes both DC and fast edges properly.

Steve