Multiple frequency intermodulation simulation software

[darkspeed]

Anyone have a good source for Multiple frequency intermodulation simulation software?

Thanks

[poynt99]

What is it you want to simulate exactly, and what type of output do your want?

.99

[darkspeed]

Intermodulation between frequencies

enter multiple frequency specifications and intermodulate them with amplitude and phase adjustment

i need to mix 2 to 5 frequencies and see the resulting waveform

i am looking at fourier coefficients

maybe a front end for matlab?

[napper]

maybe this will help - sines only though

forgot: http://www.overunity.com/index.php?action=downloads;sa=view;down=216

take care.

nap

[darkspeed]

Thanks Nap.. I need that programs big brother 

[poynt99]

Intermodulation between frequencies

enter multiple frequency specifications and intermodulate them with amplitude and phase adjustment

i need to mix 2 to 5 frequencies and see the resulting waveform

i am looking at fourier coefficients

maybe a front end for matlab?

Matlab might be the best bet for this requirement. Mixing/intermodulating is essentially multiplying two or more waveforms together.

Personally, I would do it in PSpice using analog behavior modeling (ABM) whereby ideal multiplier blocks are employed. Use as many frequency sources (of various wave forms) as you want and vary the phases of each. Then view the output using a scope and/or FFT to see Fourier components.

But that's just me 

.99

[MileHigh]

Hey Poynt, plug all of those waveforms into a "rotator."  The rotator is based on a quadrature oscillator that will rotate any waveform on an X-Y plane by an angle theta.

I am going to pull this from memory so here goes (might not be correct):

x-prime = x(cos(theta)) + y(sin(theta))

y-prime = x(sin(theta)) -  y(cos(theta))

So your input waveform could be one dimensional on the x or the y axis.  Or, you could input two waveforms into the rotator, one on the x axis and the other on the y axis.

If theta is (omega*t), then your are continuously rotating the input waveform at 2-pi-omega Hertz.

In plain English you are making a Super Spirograph that will produce all kinds of pretty patterns!  lol   They do it for laser shows all the time!

To do this circuit you need a nice quadrature oscillator with a variable frequency.  Not so easy to do that the old fashioned analog way.  Then the rest can be done with operational amplifiers and away you go!  Plug the outputs in to the X and Y axes of your analog scope and see the show.  Much better with a laser though!  lol  (I used to do laser light shows many many moons ago.)  <<< OOPS!  I also forgot that you need analog multiplier chips! >>>

Or, the whole thing could be whipped up in software quite easily.  Nice sliders for your x, y, and omega values and look at the laser light show on your computer monitor.

MileHigh

[darkspeed]

Where is my Etch A Sketch?

99. - PSpice is a good idea!

good one MileHigh!

Too bad they can include all the unknown anomalies in the software! I guess that is where it all falls down... 

[MileHigh]

Here is the X-Y plotting on a virtual scope but without the rotation function spinning the design:
http://www.mathcats.com/explore/lissajous/lissajous.html

A nerdy one:
http://www.nomad.ee/soft/java/ddstest.html

Laser but still without rotation:
http://www.youtube.com/watch?v=WDDG6TAS0lU

Finally, the jackpot, this one has the rotation:
http://www.youtube.com/watch?v=yTP_yfbT83I&feature=related
You can see how the patterns are more "pleasing" and floral looking.

The proper formula to rotate coordinates:

x' = x*cos(theta) - y*sin(theta)
y' = x*sin(theta) + y*cos(theta)

MileHigh

[wings]

modular software synthesizer

freeware


http://www.andyware.com/abox2/index.html

UPDATED

here oscillator tutorial

http://www.andyware.com/abox2/tutorials/tutorial_01/index.html

[poynt99]

Here is a demo of how this can be done in PSpice:

Input amplitude is 1Vp on each generator, sine wave, 0 degrees phase. 1kHz x 2kHz x 3kHz x 4kHz x 5kHz.

Shown is the wave forms after each multiplication, then a FFT of all 5.

.99

[darkspeed]

Brilliant!  Thanks Guys!

[MileHigh]

Darkspeed:

To help you understand what you will see with the FFT plots I will give you a basic example.

Suppose you have a 10 KHz sine wave and you multiply it by a 1 KHz sine wave.

What you will see is is a main spike at 10 KHz and and a spike at 9 KHz and another spike at 11 KHz.  So you get two spikes, one at (10-1) KHz and another at (10+1) KHz.  Those spikes are called sidebands and that is how AM radio works.

The reason for this is fairly complicated but the simple explanation is that both main frequencies exist at "positive" and "negative" frequencies.  So when you multiply two frequencies together you get this effect.  If you add them together then you don't see this effect.  Poynt is probably an expert at this.

If you look at all the spikes on the FFT that Poynt posted you should be able to explain why each spike is there because of the positive and negative frequency effects.

MileHigh