[Elecraft] On zero beating

Thu Jan 17 22:38:47 2002

On Thursday 17 January 2002 15:04, [email protected] wrote:

> For you fellow beginners, I was FINALLY enlightened when installing
> the AF filter the other nite. The manual said to zero beat the
> CONTINUOUS tone at 7000.00. MAGICALLY WHEN THERE IS A CONTINUOUS TONE
> ZERO THE DEFINITION OF BEAT BECOMES TOTALLY OBVIOUS. As soon as you
> are dead on the two tones sound as if they are one tone which has a
> rhythmic rise and fall of the tone. This rise of the tone is the
> beat.

Yup...that rising and falling "beat" represents wave interference 
between the two frequencies; The phase difference between the two 
signals cycles at a rate equal to that difference. And when the rate of 
that "beat" is zero, you've achieved "zero beat". As you tune though a 
CW signal you hear a pitch equal to the difference between the recieve 
center frequency and the transmitted frequency. 

In fact, your violin isn't *perfectly* tuned until the beat note goes 
away...but those microtonal phase differences are what gives an 
ensemble its "rich" sound. 

 73 de Maggie K3XS

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