# Re: Frequency Splitting

```Original poster: "Daniel McCauley" <dhmccauley@xxxxxxxxxxxxxxxxxxxxxxxxxx>

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When two resonant circuits are coupled together, the frequency response contains two distinct peaks at two different frequencies. This is a result of each circuit seeing "more" of the capacitance of the other's circuit when they are coupled together. So, the fres of one goes up, and the fres of one goes down, and this is what you see when you perform an AC response of the coupled resonant circuits.
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The beat frequency is the upper pole - the lower pole. The beat frequency is also the frequency at which primary notching occurs. Richie Burnett has some good
```theory on this subject on his website.

Dan

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```>We could take two identical tank circuits and couple them. We will
>still get a beat frequency.
>
>Ah , but what about "frequency splitting?"
>
>Be realistic, they are identical tank circuits. One tank could not
>possibly operate at a different frequency then the other. There is
>no "splitting".
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Doesn't a "beat frequency" result from two signals of different frequency? If so, what is the source of the other frequency? If not, how else does a "beat" result?
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>However both tank circuits will now operate at a frequency that is
>different from the uncoupled state.

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Are you saying the above observed "beat frequency" is the difference between the common "coupled frequency" and the common "uncoupled frequency"?
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-Phil LaBudde

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