[time-nuts] Hetrodyning concept

[Javier Herrero]

Hello,

No... if you heterodine, you multiply, so if both frequencies are the 
same you have sin(wt)^2 = 0.5(cos(0) - cos(2wt)), so you have DC plus 
the double freq. If they are pi radians appart, you have 
sin(wt)*sin(-wt) = 0.5(cos(2*pi) - cos(2wt)), so you have -DC plus the 
double freq. If they are in quadrature, ie pi/2 appart, you have 
sin(wt)*cos(wt) = 0.5(sin(0) + sin(2wt), so you have the double freq. 
but no DC.

Best regards,

Javier, EA1CRB



On 27/4/20 10:08, Taka Kamiya via time-nuts wrote:
> I have a question on heterodyining concept.
> Say you have f1 and f2.  Say you have f1 <> f2.  Then the product is |f1+f2| and |f1-f2|.  (fundamental is not considered here)
> What would happen f1 = f2?  If phase is the same, it will be 2sin(omega t).  (amplitude doubles)  If phase is an odd multiple of pi radian different, result is zero.  (cancels out each other)
> What I am trying to do is to first, understand this in case where f1 = f2, and second, mix f1 and f2 and get f3, which is a sum of f1 and f2.  Doubling won't do.
> Can someone help me understand this?  I haven't seen discussion of cases where source frequencies are equal anywhere.
>
>
>
> ---------------------------------------
> (Mr.) Taka Kamiya
> KB4EMF / ex JF2DKG
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Javier Herrero
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