Harmonic carriers

I am trying to understand how an harmonic carrier is properly applied and what the effect is.

For example, if I tale a 1KHz sinewave and use it to AM a 16KHz sinewave do I get harmonics higher than the 16KHz?

Any expert insight?

Martin Harris

Reply to
Martin Harris
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I'm far from an expert, but that's pretty basic.

You will get energy at 16-1 and 16+1 KHz. No harmonics of the carrier.

You will get harmonics/splatter if you overmodulate.

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Reply to
Hal Murray

Ideally, no. But, no system is perfectly linear. There will be some level of harmonic response. How much is acceptable and why are the questions.

Reply to
Simon S Aysdie

Not harmonics - sidebands. If your 16KHz is a pure sine wave, and your

1 KHz is a pure sine wave, and your modulator is "linear" (modulation is a non-linear function - what I mean here is that the amplitude of the carrier exactly follows the input), then the output will consist of a signal at 15KHz, 16KHz, and 17KHz - the two sidebands will be half the amplitude of the carrier (16KHz)

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Hope This Helps! Rich

Reply to
Rich Grise

As has been said by the other posters, if you start with ideal sine waves and modulate linearly, the entire output spectrum will consist of just three pure sine waves.

Perfect amplitude modulation wouldn't generate harmonics of the carrier. However, AM is often applied to a high-level stage or power amplifer that is operating in some mode other than class A with less then perfect high-pass filtering. Consequently, that stage will generate harmonics of the carrier frequency. And if the carrier is being modulated, so will the harmonics. But it is not the modulation process that generates the harmonics of the carrier.

Does that answer your question? If not, maybe you can supply some additional details.

Chuck

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Reply to
Chuck

Due to the nature of my inquiry, it was assumed I wanted to minimize harmonics. Understandable by convention. But actually, I would like to _maximize_ them, especially on the higher side. IOW to obtain as many higher above audio harmonics of the 16KHz as possible while still using something like the sinewave AM approach originally described, ie. not squarewaves. What would be the best way of achieiving this?

Martin Harris

Reply to
Martin Harris

"Martin Harris"

** Physics is not game where YOU get to make up any rules you like - f****it.

Harmonics are generated by distorted looking wave shapes - NOT sine waves.

A square wave has all the odd numbered harmonics included - 3rd, 5th 7 th etc. .

Asymmetrically distorted sine waves have the even ones, 2nd 4th, 6th etc.

A mix of the two gives you the lot.

An electric guitar fuzz box does this to a sine wave input.

...... Phil

Reply to
Phil Allison

Not quite correct; one gets the sum (16+1), the difference (16-1),and the originals (1 and 16) KHz.

Reply to
Robert Baer

Why is it that "everyone" is ignoring *both* of the original input frequencies? Perhaps one needs to use a spectrum analyzer...

Reply to
Robert Baer

Use a filter tuned to 17KHz.

Reply to
Robert Baer

Kind of depends on the circuit, doesn't it, Robert? What if a DBM were used?

If the intent is to produce modulated harmonics of a sine wave carrier, I think the answer has been given: you must modify (i.e., distort) the sine wave carrier in order to produce harmonics. For example, use a circuit that distorts the sine wave by clipping it. The modulator could perform this function.

A pure sine wave simply contains no energy other than at its own frequency. If you're not willing to distort a sine wave, you can't produce harmonics. Period.

Without knowing more about the parameters of your enterprise, it is really difficult to respond further.

Chuck

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Reply to
Chuck

Just generate a 16 KHz sawtooth; you'll get harmonics:

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Or, if you want there to be harmonics of 1 KHz all around the 16 KHz carrier, them AM it with a 1 KHz sawtooth.

Have Fun! Rich

Reply to
Rich Grise

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