Generate a random vibration profile?

Hey all,

I was wondering if anyone can think of a way to generate vibration profile curves using matlab similar to this example:

http://www.motorola.com/testservices/random1.html

This is written really well but it offers no actual explanation of how these curves would be created, I'm assuming you couldn't do this with a particular function and probably have to hand pick 'breakpoints' and then just plot them?

Thanks! JT

[Sean de Wolski]

Is PSD just determined experimentally for certain frequencies? That's what the graph look like at least.