01-17-2012 08:49 PM
hi
just wondering if anyone can point me to the right direction here. Basically i just want to generate/create a series of odd harmonics - ranging up to the 30th harmonics - and would like to know how to do this; is it simply a matter of creating a series of sine waves multiplied by the fundamental or would i need to use such fft or psd functions of sort? Or any kind of function and to what use is the THD model? Any suggestions are welcome
thanks
01-17-2012 08:57 PM
waveform multiplied by amplitude, dT multiplied by odd integers resample waveform- add. 30 isn't odd (nor old)
01-17-2012 09:26 PM
I missed the THD part.
Total Harmonic Distortion I could write an article or point you to a definition or say it is a measure of fidelity
01-18-2012 07:24 AM
hi there
thanks for the quick response. Not to concerned with the THD right now but ill give a good read later on.
but right now i just need to generate a series of odd harmonics to get me started. The few methods i've exercised haven't really satisfied me in a way that im sure is the right way to go. Just want to understand reading from your first post; ''waveform multiplied by amplitude'; is that something to do with fiddling around the function generator or would i have to use a few numeric functions. And dT would mean i have to use the "Get Waveform Components" function?
ill try to produce something today hopefully.and get back.
thanks very much.
01-18-2012 09:50 AM
I'll keep an eye out for your example- Good luck!
01-18-2012 10:16 AM
Fourier theorem says that any periodic signal can be broken down into a sum of sine waves, each with a given amplitude and phase, relative to the period in question.
Each sine wave can be specified as V[i] = A[i] * sin (2 * pi * F[i] * t + phase[i])), where:
A[i] is the amplitude of this component.
F[i] is the frequency of this component.
phase[i] is the phase shift of this component.
t is the time since T0.
You didn't mention phase, let's disregard that for now.
You didn't mention amplitude, lets' assume all A[i] values are 1.0
For your purposes, F[i] is going to be 1, 3, 5, 7....29 (odd harmonics below 30)
So, step thru time at your desired sample rate:
The voltage will be:
sin(2 * pi * F * t) + sin (2 * pi * 3 * F * t) + sin (2 * pi * 5 * F * t).....
you would have one loop for TIME steps, and one for harmonic steps.
Blog for (mostly LabVIEW) programmers: Tips And Tricks